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Examination of joint delamination in single wythe pier and panel masonry fences

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Title:
Examination of joint delamination in single wythe pier and panel masonry fences
Creator:
Shepherd, Michael Anthony ( author )
Place of Publication:
Denver, CO
Publisher:
University of Colorado Denver
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English
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1 electronic file (90 pages). : ;

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Subjects / Keywords:
Masonry -- Joints ( lcsh )
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bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

Notes

Review:
Single-wythe masonry fences are often supported on discrete piers instead of continuous foundation systems; for these cases, the panel must span between the piers. Many pier and panel single-wythe masonry fences have exhibited horizontal joint delamination near the bottom of the panel generally accompanied with sagging of the bottom several courses of masonry. The literature is silent on explanations for this phenomenon. Some engineers have attempted various design measures to address the problem but results have been mixed. Research at the University of Colorado Denver has been directed at ascertaining the cause of the delamination and the associated sagging. Linearly elastic FEM models using different aspect ratios have been developed to examine stresses within the fence panel and a laboratory experiment has been conducted using a full scale masonry fence with an aspect ratio known to have failed in the past. The experimental work captures non-linear behavior of the panel.
Thesis:
Thesis (M.S.)--University of Colorado Denver. Civil engineering
Bibliography:
Includes bibliographic references.
System Details:
System requirements: Adobe Reader.
General Note:
Department of Civil Engineering
Statement of Responsibility:
by Michael Anthony Shepherd.

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University of Colorado Denver
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|Auraria Library
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All applicable rights reserved by the source institution and holding location.
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904621482 ( OCLC )
ocn904621482

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EXAMINATION OF JOINT DELAMINATION IN SINGLE WYTHE P IER AND PANEL MASONRY FENCES by MICHAEL ANTHONY SHEPHERD B.S., University of Colorado Denver, 2011 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Master of Science Civil Engineering 2014

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ii This thesis for the Master of Science degree by Michael Anthony Shepherd has been approved for the Civil Engineering Program by Frederick Rutz, Chair Kevin Rens Chengyu Li November 17th, 2014

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iii Shepherd, Michael Anthony (M.S., Civil Engineering) Examination of Joint Delamination in Single Wythe P ier and Panel Masonry Fences Thesis directed by Assistant Professor Frederick Ru tz ABSTRACT Single-wythe masonry fences are often supported on discrete piers instead of continuous foundation systems; for these cases, the panel must span between the piers. Many pier and panel single-wythe masonry fences have exhibite d horizontal joint delamination near the bottom of the panel generally accompanied with sagging of the bottom several courses of masonry. The literature is silent on exp lanations for this phenomenon. Some engineers have attempted various design measures to address the problem but results have been mixed. Research at the University of Colo rado Denver has been directed at ascertaining the cause of the delamination and the associated sagging. Linearly elastic FEM models using different aspect ratios ha ve been developed to examine stresses within the fence panel and a laboratory experiment has been conducted using a full scale masonry fence with an aspect ratio known to have fa iled in the past. The experimental work captures non-linear behavior of the panel. The form and content of this abstract are approved. I recommend its publication. Approved: Frederick Rutz

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iv DEDICATION I dedicate this work my friends, family, and loved ones whose lives I have had little involvement in throughout the duration of gr aduate school.

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v ACKNOWLEDGMENTS I would like to thank General Shale Inc., Mike Schu ller and Donald Harvey of Atkinson-Noland and Associates, Bill Kepler of the US Bureau of Reclamation and my advisor Dr. Frederick Rutz for their support and ti me.

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vi TABLE OF CONTENTS CHAPTER I. BACKGROUND ..................................... ................................................... ..................... 1Advantages of Pier and Panel Walls ................ ................................................... .... 3Disadvantages of Pier and Panel Walls ............. ................................................... .. 4Problem Description ............................... ................................................... ............. 4II. LITERATURE REVIEW ............................. ................................................... ............... 7BIA Technical Note 45 Brick Masonry Noise Barrier W alls Introduction .......... 7BIA Technical Note 45A Brick Masonry Noise Barrier Walls – Structural Design ................................................... ................................................... ........................... 8NCMA TEK 14-15B Allowable Stress Design of Pier and Panel Highway Sound Barrier Walls ..................................... ................................................... ................... 8Masonry Sound Barrier Walls and Fences ............ .................................................. 9Building Code Requirements and Specification for Ma sonry Structures ............. 10The Composite Action of Brick Panel Walls Supported on Reinforced Concrete Beams ............................................. ................................................... .................... 10Masonry Structures Behavior and Design, 3rd Edition ......................................... 11Single-wythe Brick Panel Fence Failures ........... .................................................. 12III. FINITE ELEMENT ANALYSIS ...................... ................................................... ...... 13Background ........................................ ................................................... ................ 13Material Properties ............................... ................................................... .............. 14Boundary Conditions ............................... ................................................... .......... 15Results Simply Supported Condition .............. ................................................... 16Results Fixed Against Rotation .................. ................................................... ..... 24Results Fixed End Beam of One Course ............ ................................................ 31

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vii IV. HYPOTHESIS .................................... ................................................... ..................... 33Background ........................................ ................................................... ................ 33Hypothesis 1....................................... ................................................... ................ 33Hypothesis 2....................................... ................................................... ................ 34Hypothesis 3....................................... ................................................... ................ 36Hypothesis 4....................................... ................................................... ................ 38Hypothesis 5....................................... ................................................... ................ 39V.OBJECTIVE OF STUDY .............................. ................................................... ............ 41VI. EXPERIMENT DESCRIPTION ........................ ................................................... ..... 43Construction of Piers.............................. ................................................... ............ 44Construction of Wood Formwork ..................... ................................................... 48Construction of Bond Beam.......................... ................................................... ..... 52Construction of the Panel and Dry stack Acrylic She ets ...................................... 59VII. TEST RESULTS ................................. ................................................... ................... 65VIII. CONCLUSION .................................. ................................................... ................... 73REFERENCES ........................................ ................................................... ...................... 76

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viii LIST OF TABLES TABLE III.1 Finite Element Analysis Material Inputs. .... ................................................... .......... 15VI.1 Fine Grout Mixture Proportions. .............. ................................................... ............. 53VI.2 Grout Cube Strength Test Results. ............ ................................................... ............ 53

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ix LIST OF FIGURES FIGURE I.1 The ruins of Forum Romanum in Rome, Italy. .... ................................................... ...... 2I.2 Raleigh Beltline sound barrier wall. .......... ................................................... ................. 3I.3 Example of Delamination. ...................... ................................................... .................... 5III.1 SX Stress Results 1:1 Aspect Ratio. ......... ................................................... ............. 17III.2 SY Stress Results 1:1 Aspect Ratio. ......... ................................................... ............. 17III.3 SX Stress Results 1:0.75 Aspect Ratio. ...... ................................................... ........... 18III.4 SY Stress Results 1:0.75 Aspect Ratio. ...... ................................................... ........... 18III.5 SX Stress Results 1:0.66 Aspect Ratio. ...... ................................................... ........... 19III.6 SY Stress Results 1:0.66 Aspect Ratio. ...... ................................................... ........... 19III.7 SX Stress Results 1:0.58 Aspect Ratio. ...... ................................................... ........... 20III.8 SY Stress Results 1:0.58 Aspect Ratio. ...... ................................................... ........... 20III.9 SX Stress Results 1:0.50 Aspect Ratio. ...... ................................................... ........... 21III.10 SY Stress Results 1:0.50 Aspect Ratio. ..... ................................................... .......... 21III.11 SX Stress Results 1:0.33 Aspect Ratio. ..... ................................................... .......... 22III.12 SY Stress Results 1:0.33 Aspect Ratio. ..... ................................................... .......... 22III.13 SX Stress Results 1:0.25 Aspect Ratio. ..... ................................................... .......... 23III.14 SY Stress Results 1:0.25 Aspect Ratio. ..... ................................................... .......... 23III.15 SX Stress Results 1:1 Aspect Ratio. ........ ................................................... ............ 24III.16 SY Stress Results 1:1 Aspect Ratio. ........ ................................................... ............ 25III.17 SX Stress Results 1:0.75 Aspect Ratio. ..... ................................................... .......... 25III.18 SY Stress Results 1:0.75 Aspect Ratio. ..... ................................................... .......... 26III.19 SX Stress Results 1:0.66 Aspect Ratio. ..... ................................................... .......... 26

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x III.20 SY Stress Results 1:0.66 Aspect Ratio. ..... ................................................... .......... 27III.21 SX Stress Results 1:0.58 Aspect Ratio. ..... ................................................... .......... 27III.22 SY Stress Results 1:0.58 Aspect Ratio. ..... ................................................... .......... 28III.23 SX Stress Results 1:0.50 Aspect Ratio. ..... ................................................... .......... 28III.24 SY Stress Results 1:0.50 Aspect Ratio. ..... ................................................... .......... 29III.25 SX Stress Results 1:0.33 Aspect Ratio. ..... ................................................... .......... 29III.26 SY Stress Results 1:0.33 Aspect Ratio. ..... ................................................... .......... 30III.27 SX Stress Results 1:0.25 Aspect Ratio. ..... ................................................... .......... 30III.28 SY Stress Results 1:0.33 Aspect Ratio. ..... ................................................... .......... 31III.29 10ft beam deflection. ...................... ................................................... ..................... 31III.30 12ft beam deflection. ...................... ................................................... ..................... 31III.31 14ft beam deflection. ...................... ................................................... ..................... 32III.32 16ft beam deflection. ...................... ................................................... ..................... 32III.33 18ft beam deflection. ...................... ................................................... ..................... 32III.34 20ft beam deflection. ...................... ................................................... ..................... 32IV.1 Cracking of bed joints due to corrosion of joi nt reinforcement. ............................... 3 5IV.2 Load distribution on beam supporting brick cav ity wall. ......................................... 36IV.3 Loss of contact between beams and masonry pane ls. ............................................... 37IV.4 Detail of reinforcement detailing. ........... ................................................... ............... 40V.1 Masonry Fence Panel showing delamination....... ................................................... ... 41VI.1 Mixing of mortar with sand. .................. ................................................... ................ 44VI.2 Addition of water to achieve desired consisten cy. ............................................... .... 45VI.3 Construction of the first pier. .............. ................................................... ................... 45VI.4 First pier nearing completion. ............... ................................................... ................. 46VI.5 Construction of second pier commencing. ...... ................................................... ...... 46

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xi VI.6 Construction of the second pier. ............. ................................................... ............... 47VI.7 Second pier nearing completion. .............. ................................................... ............. 48VI.9 Construction of wood form. ................... ................................................... ................ 49VI.10 Detail of wood form with stringers. ......... ................................................... ............ 49VI.11 Installation of first plywood sheet. ........ ................................................... .............. 50VI.12 Installation of second plywood sheet. ....... ................................................... ........... 50VI.13 Completed plywood brace installed. .......... ................................................... .......... 51VI.14 Installation of the removable sand support. ................................................... ........ 51VI.15 Removable sand support installed. ........... ................................................... ........... 52VI.16 Reinforcing steel markings. ................. ................................................... ................ 54VI.17 Bond beam prepared for grouting. ............ ................................................... ........... 54VI.18 Detail of bond beam bricks and reinforcing st eel. .............................................. .... 55VI.19 Preparations made for grout prism pours...... ................................................... ....... 55VI.20 Detail of grout prism form prior to pouring o f grout. .......................................... ... 56VI.21 Grout prim filled with fresh grout. ......... ................................................... ............. 56VI.22 Bond beam with reinforcement fully grouted. ................................................... .... 57VI.23 Detail of left end of bond beam. ............ ................................................... .............. 57VI. 24 Detail of right end of bond beam. .......... ................................................... ............. 58VI.25 Grout prism prepared for testing............. ................................................... ............. 58VI.26 Testing of grout prism. ..................... ................................................... ................... 59VI.27 Laying the first few courses of masonry...... ................................................... ........ 60VI.28 Approximately 5 ft of masonry laid........... ................................................... .......... 60VI.29 Completion of the experimental panel. ....... ................................................... ......... 61VI.30 The completed experimental panel ............ ................................................... .......... 61VI.31 Masonry sandwiched between plywood brace and acrylic sheets. ......................... 62

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xii VI.32 Expansion joint. ............................ ................................................... ....................... 62VI. 33 Tape on acrylic sheets. .................... ................................................... .................... 63VI.34 Detail of Tape on acrylic sheets. ........... ................................................... ............... 63VI.35 Awaiting removal of sand support. ........... ................................................... ........... 64VII.1 Removal of sand support. .................... ................................................... ................. 65VII.2 Detail of sand support removal. ............. ................................................... .............. 66VII.3 Panel behavior after during sand removal. ... ................................................... ........ 66VII.4 Panel behavior after removal of sand. ....... ................................................... ........... 67VII.5 Final panel behavior. ....................... ................................................... ..................... 68VII.6 Detail of bond beam at left pier support. ... ................................................... ........... 68VII.7 Detail of left end of panel at pier support. ................................................... ............ 69VII.8 Detail of deflection at the bottom center of the panel. ........................................ .... 69VII.9 Detail of deflection at the top center of the panel. ........................................... ....... 70VII.10 Detail of reinforcement bond failure at left end of panel. .................................... 71VII.11 Detail of reinforcement bond failure at righ t end of panel. ................................... 72

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xiii LIST OF ABBREVIATIONS in inch ft foot psi pounds per square inch ksi kips per square inch lbs/ft3 pounds per cubic foot

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1 CHAPTER I BACKGROUND Since the dawn of time when mankind first created the wheel and began traversing the land the sound of wheeled traffic co ngregating has been the bane of peace and quiet. While the Romans were deft engineers whe n called upon to span a chasm or bring water to a city, deadening the sound of comme rcial traffic escaped even the power of Caesar: In 45 B.C.E., Julius Caesar issued an edict which b anned carts, wagons, and chariotsÂ… from driving in the city between sunrise and midafternoon. This was a masterpiece of bad urbanism, since, although it did something to make daytime walking and riding in Rome possible, it immediately diverted all RomeÂ’s commercial traffic into the night hours depriving m ost Romans of their sleep. Roman carts had wooden wheels with iron tires, and the grinding and clanking of their progress over the ruts and stone pavements ra ised a din that mingled with the braying and lowing of beasts, the shouts of the carters, the merchants bellowing quarrels, and the crash and scrape of goo ds being loaded and unloaded. This went on all night long, and a stone could hardly sleep through it (Hughes 2012).

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2 Figure I.1 The ruins of Forum Romanum in Rome, Ital y. Now only pedestrian traffic passes over the ancient cobblestones. Despite the passage of time little has changed; the sound of traffic still breaks the silence people crave. However where ancient engine ering was not able to solve modern engineering has; there are sound barriers which lin e busy streets, highways, and interstates. Since the first highway sound barrier was installed in the United States in 1963 (FHWA 2000) the need for noise abatement has increa sed with each year. Sound barrier walls can be constructed out of a variety of materi als; typically the material type that is chosen is a function of its ability to either refle ct or absorb sound. The study of sound abatement is separate field in its own right and be yond the scope of this paper. The Federal Highway department has published a chart de tailing the sound absorption properties of various common materials (FHWA 2000). Based on list of materials (which excludes brick) CMU and concrete have the greatest transmission loss, and is what the

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3 majority of sound barriers are constructed out of. Many localities have turned to brick for noise barriers, as it makes for an attractive wall, especially in areas that have a history of building in brick. The Raleigh Beltline is one such project, which is shown in Figure I.2. Figure I.2 Raleigh Beltline sound barrier wall. Photo by Melissa Mertz. Used with permission. Advantages of Pier and Panel Walls Noise reduction is the primary reason for building a masonry fence, however, noise reduction is realm of architects and the spec ifics of noise reduction are beyond the focus of this thesis. Additionally, single-wythe pi er and panel walls use materials efficiently; walls can span up to twenty feet in le ngth or height between piers and are often the best choice for a sound barrier (Schuller et al. 2007). Previously most walls spanning similar distances were cantilevered walls which required extensive footing excavation, as well as vertical and horizontal rein forcement. Because the fence panel spans between piers, which serve as the main struct ural elements, less materials are used

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4 than in a wall with a continuous footing. Additiona lly pier and panel walls can be built on an existing site with fewer disturbances to existin g utilities (Schuller et al. 2007). Disadvantages of Pier and Panel Walls Schuller et al. et al. (Schuller et al. 2007) list s two disadvantages of pier and panel fences, the pier can catch traffic when fences are near busy roads more than a smooth wall. At high speeds this concern becomes more pron ounced. Construction of pier and panel fences may also require additional constructi on inspection to ensure adequacy. Problem Description While many pier and panel walls in service are pref orming well, some have begun to deteriorate and have developed a problems near t he bottom center of the panel in which the bottom course or courses of masonry separ ate and sag away from the remaining panel. The author has chosen the term ‘de lamination’ to describe this phenomenon, as the panel separates into layers, or courses. Often this delamination involves the bottom course or courses, which also c ontain the tension tie reinforcement in the panel. Deflections can be quite pronounced in s ome cases being several inches. Most perplexing is that to date the author is not aware of the phenomena occurring consistently and indeed delaminating panels are often located ne xt to panels which are not showing similar symptoms of distress. Figure I.3 illustrate s an example of the masonry fence delamination.

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5 Figure I.3 Example of Delamination. Photo courtesy of Frederick Rutz. Used with permiss ion. Several design guides exist (BIA 1992, BIA 2001, Sc huller et al. 2007), and included in them are recommendations intended to en sure adequate performance. Recent literature (Swink 2014) has addressed the deteriora tion of single-wythe pier and panel walls, but does not address specific types of deter ioration. The primary cause according to Swink is poor workmanship or substandard materia ls. Some engineers have attempted various design measur es specifically to address the problem but results have been mixed. Many of t hese attempts involve trying to reinforce across the bed joints in the bottom sever al courses of masonry with small gauge wires. However, because most brick used in pier and panel walls is not specifically designed to be reinforced the brick core holes do n ot align vertically, making this installation impossible in fences where the panels are laid in running bond. The author

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6 wishes to develop an understanding of the root caus e or causes of the problem before offering solutions to it.

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7 CHAPTER II LITERATURE REVIEW The initial work on this thesis involved the revie w of masonry textbooks, research papers, building codes, and design guides related t o masonry fences. No published research was found explaining the cause of masonry fence delamination. Design guides commonly address design assumptions, but these guid es are silent on acknowledgement of masonry fence delamination. As far as the author is aware no research exists currently investigating the cause of the problem. The followi ng literature review helped guide research into the development of five hypotheses fo r the cause of masonry fence delamination. The experiment in this thesis was des igned to test one of the hypotheses, and the results are reported in Chapter VII. The ma in purpose of the literature review is to familiarize the reader with the current state of kn owledge on the subject. BIA Technical Note 45 Brick Masonry Noise Barrier W alls Introduction This short publication by the Brick Industry Assoc iation (BIA 2001) gives designers a thorough overview of the purpose of mas onry fences, which are primarily designed to reduce sound transmission along busy tr affic corridors. Also covered are design considerations for a variety of highway nois e barriers types. The BIA differentiates single-wythe panel walls as being either pier and panel walls (expansion joints, and assumed simply support ed behavior) or pilaster and panel walls (no expansion joints, and assumed fixed suppo rt behavior). This differs from other design guides (Schuller et al. 2007) which refer to both types of boundary conditions as pier and panel walls. Other publications (NCMA 200 4) are silent on this naming

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8 convention and only provide design information for panels with expansion joints at the piers. With respect to pier and panel walls joint reinfo rcement is recommended as a means of resisting lateral loads and should be dist ributed throughout the panel height. Reinforcement at the bottom of the panel should be designed for a combination of the maximum out of plane and in plane flexure. Becaus e this publication is intended as a primer, no specific design examples are given. BIA Technical Note 45A Brick Masonry Noise Barrier Walls – Structural Design This BIA publication (BIA 1992) gives some design examples of several different wall types covered in the preceding technical notes (BIA 2001). While useful in walking the designer through the design process, the public ation assumes pier and panel walls will be fully supported along the contact surface with t he ground. The justification for this assumption is that the noise barrier function of th e wall would necessitate there to be no gap to transmit sound. As a result of this design a ssumption the publication does not attempt to design a pier and panel wall for in plan e flexure. NCMA TEK 14-15B Allowable Stress Design of Pier and Panel Highway Sound Barrier Walls This short publication by the National Concrete Ma sonry Associate (NCMA 2004) provides the designer with both general infor mation, and a step by step design example of a pier and panel wall utilizing concrete masonry units (CMU). The publication serves as a condensed version of inform ation available in the BIA technical

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9 notes and is more proscriptive in nature, providing equations and tables for the designer to use. For the panel to adequately resist lateral loads th e NCMA recommends the use of either joint reinforcement or evenly spaced bond be ams throughout the panel height. For the treatment of in plane dead loads the NMCA state s that pier and panel walls will be designed as deep beams. However, no equations are g iven for in plane loads and instead a design table with proscriptive requirements based o n panel clear span is provided. The proscriptive depth and reinforcement of this bo nd beam varies and is as deep as 40in for a 20ft span, and height of 10ft. It sh ould be noted that the author back calculated the capacity of the bond beams and they are capable of fully supporting the weight of the entire panel as a uniform distributed load, neglecting any deep beam action. The depth and reinforcement layout for bottom bond beams listed in this publication is markedly different than any recommendation for bric k pier and panel walls, and much more robust. Masonry Sound Barrier Walls and Fences Masonry sound barrier walls and fences (Schuller e t al. 2007) is a joint publication between the Rocky Mountain Masonry Inst itute (RMMI) and AtkinsonNoland & Associates. It addresses all aspects of ma sonry fence design to include, noise reduction, aesthetics, structural design, and econo mics with respect to design. Pier and panel walls are addressed in detail, specifically w ith an eye toward reducing costs and maximizing pier spacing. Recommended practice is fo r panels to have movement or expansion joints at each pier, and for flexural rei nforcement to be distributed throughout the wall.

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10 While no design example is given for the designer to follow, the end of the publication includes orthographic drawings of pier and panel walls constructed with a variety of materials. Additionally design assumptio ns and costs per linear foot based on wall height are given for estimation use by designe rs. Building Code Requirements and Specification for Ma sonry Structures Current code requirements (TMS 2011) do not specif ically address the design of pier and panel walls. However, the 2011 edition for the first time addresses the design of deep beams with proscriptive requirements which inc lude the inclusion of horizontal flexural reinforcement in the form of joint reinfor cement for the bottom half of the total depth of the deep beam. Spacing is not to exceed on e fifth of the depth of the beam or 16 inches whichever is less. The Composite Action of Brick Panel Walls Supported on Reinforced Concrete Beams The purpose of this study (Wood 1952) was to econom ize the design of reinforced concrete grade beams supporting masonry walls of ho uses. Brick walls of varying thickness, with and without openings were built on top of a simply supported reinforced concrete beam. Strain gauges were able to measure s tresses in the wall and beam to determine design bending moments. Two tests in part icular are of interest with respect to pier and panel masonry fences. In the first test an unreinforced 9in wall with a h eight of 8ft and span of 10ft was constructed with no support beam and subjected to a pplied loads at 4 points along the top of the wall. Flexural stresses from applied loads created several vertical cracks and one

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11 large horizontal crack at the joint between the thi rd and fourth course. It was noted that deflection was greater at this point because of the horizontal cracking. Arching in the wall occurred and the remaining bricks more or less hung in tension from the arch. Another test in particular may prove to be enlighte ning with respect to the occurrence of delamination of pier and panel masonr y fences. An 11in brick cavity wall was constructed atop a 12in by 7in reinforced concr ete beam with a bond breaking bituminous layer placed between the wall and beam. The formation of an arch within the wall formed at a distance away from the support and into the clear span of the beam. Thus both the wall and beam shared in carrying the load of the wall. At the center of the span, vertical stresses were very small and the bea m deflected away from the wall above it. The remainder of the tests conducted includes fenes trations in the walls such as windows and doors and their effect on arching and l oad sharing between beam and wall. Their applicability to the causation of masonry fen ce pier and panel delamination is of very limited value. Masonry Structures Behavior and Design, 3rd Edition This masonry design textbook (Dyrsdale and Hamid 20 08) was written to accompany the 2008 edition of Building Code Require ments for Masonry Structures. Prior to 2011 there were no explicit code requireme nts for the design of deep beams, and instead the authors provide two recommendations whi ch pertain to the design of fence panels as deep beams. The inclusion of both interme diate horizontal reinforcement and stirrups is recommended for the purpose of crack co ntrol in all beams with a depth greater than 32 in. Secondly, the recommendation fo r simply supported beams with a

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12 span to depth of 2 or less is to follow the strut a nd tie design procedures used for reinforced concrete, with a special emphasis paid t o the anchorage of the reinforcement. The text also summarizes the past research on the d esign of masonry walls supported by beams. Dead and imposed loads on the w all are shared by both the wall and beam based on the relative stiffness of each. With very stiff beams wall dead loads act like a uniform load on the beam. At the opposite en d of the spectrum with a very flexible beam, the dead load of the wall is carried primaril y by arching action of the wall and the beam separates from the panel at the panel midspan, maintaining contact only near the supports. Included in the text are design charts t o estimate beam stiffness relative to the wall, and determine the length of contact near the supports. Single-wythe Brick Panel Fence Failures This two page article (Swink 2014) addresses distr ess in single-wythe pier and panel masonry fences, but does not specifically des cribe delamination. Design guidance is concise, owing to the brevity of the piece, but Swink does indicate that some fence builders are utilizing steel angles to support fenc e panels, a difference not described in other literature. Distress (cracking) is attributed to three causes, poor bond between brick and mortar, insufficient cover of joint reinforcement, and wire reinforcement being used that is not hot dipped galvanized. Half of the article a ddresses the prevention of these three causes.

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13 CHAPTER III FINITE ELEMENT ANALYSIS Background A finite element study of masonry fences with vari ous aspect ratios was conducted with two objectives: a better understandi ng the masonry fence behavior and determination of an underlying cause for joint dela mination. All analysis was conducted using STAAD.Pro V8i, which is a general purpose, li nearly elastic, finite element modeling software. All fence panels were modeling u sing plate elements with a 1:1 aspect ratio (0.25ft: 0.25ft). The following masonry fence aspect ratios (span: he ight) were selected: 1:1, 1:0.75, 1:0.67, 1:0.58, 1:0.5, 1:0.33, and 1:0.25 a ll assuming a clear span of 12ft. In addition separate analysis focused on behavior of m asonry bond beams in the event that they became detached from the masonry fence. Becaus e delamination usually occurs very slowly over many years, live loads which are incide ntal and short in duration were excluded from the analysis; fences were subject to unfactored dead loads only. Once a crack propagates along the bed joint between courses of masonry, the fence panel has formed two discreet elements: the r emaining fence panel and a separate ‘beam’. This beam will be free to deflect under its own weight and may be a contributing cause in delamination. An additional goal of this f inite element study is do determine at what spans the deflection of a single course or a f ew courses of masonry may be a significant contributing factor to fence delaminati on.

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14 Beams were modeled using frame elements in STAAD.Pr o with fixed supports. Research from past studies (Wood 1952) indicates th at beams designed as simply supported will be restrained against rotation by th e weight of masonry above them and by arching loads within the panel, and thus the simply supported beam will achieve fixed conditions. As described previously, fence panels a re constructed of different bricks and so dimensions and as a result stiffness will vary d ependent on that selection. For the purposes of this study, single beams had a cross se ction of 2.75in x 2.75in which is the cross section of the bricks used in the experiment. Material Properties STAAD.Pro allows users to define material propertie s to assign to plates and members used in analysis. There is no standard size of brick used in pier and panel fences, and as a result exact material properties v ary as a function of unit size, solid or cored unit, selection of mortar type, and joint thi ckness, amongst others. As a result no material properties were measured and design values were assumed. The commentary of ASCE 7-10 (ASCE 2010) provides values for unit weig hts of materials to assume for design. For the purpose of this study a unit weight of 130lbs/ft3 was selected. Similarly the design compressive strength of 1,500psi was als o assumed. The remaining material properties were calculated according to the current code requirements in TMS-402-11 (TMS 2011) which de fines material properties such as modulus of elasticity as a function of compressive strength. A summary of material properties used in the analysis are listed below.

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15 Table III.1 Finite Element Analysis Material Inputs Unit Weight [lbs/ft3] Design Compressive Strength [psi] Modulus of Elasticity [ksi] Modulus of Rigidity [ksi] Possions Ratio Coefficient of Thermal Expansion [in/in/F] 130 1500 1050 420 0.25 4x10-6 Boundary Conditions Boundary conditions in actual masonry fences are mo re complicated than often considered in design. Boundary conditions are assum ed to either be simply supported or fixed depending on joint conditions at the end. Bas ed on design recommendations, joints at piers will be either expansion joints or constru ction joints (Schuller et al. et al 2007). In actual fences, assuming the end of the panel is in perfect contact with the construction joint the restraint is likely to occur only near th e bottom of the panels as they translate towards the piers, while the top of the panel trans lates away. This creates a complicated boundary condition to model in finite element progr am, as it is dependent on a contact surface instead of an explicit boundary condition. Initial results from panels with fixed conditions a t each end gave unrealistic panel behavior prompting a further examination of boundar y conditions of simply supported panels. Results from this study found that simply s upported panels under their own self weight have very minimal lateral translation (0.008 in), equivalent to the width of two sheets of paper or less, and dependent on aspect ra tio of the panel. Even assuming expansion due to 50 F thermal loads, lateral translation is minimal, ar ound 1/32nd of an inch (.0368in) for the entire panel. In longer pane ls (20ft) restraint against translation

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16 could prove to be more significant. Several attempt s at using compression only springs at the boundary conditions to prevent lateral translat ion produced varying results. Due to concerns about accuracy this approach was ultimatel y abandoned. Instead all panels were allowed to translate, and a comparison between rest raint against rotation and free rotation panels was made. Results Simply Supported Condition Panels designed as simply supported exhibited chan ging behavior with aspect ratio. Panels were able to achieve arching with asp ect ratios 1:1 to 1:0.50. Panels with aspect ratios less than 1:0.50 trended toward norma l beam behavior. During post processing, STAAD.Pro displays plate stress results over an index of 15 color divisions. When results indicate several orders of magnitude o f difference between tension and compression, indexing of results can result in beha vior being “lost” in a single color band. Custom values were chosen between 7psi tensi on and 21psi compression to illustrate the transition between vertical tension and compression in the panel. Vertical tension stresses were 7psi or less and all compress ive stresses were greater than 21psi in all panels regardless of aspect ratio.

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17 Figure III.1 SX Stress Results 1:1 Aspect Ratio. Stresses in the horizontal direction. Figure III.2 SY Stress Results 1:1 Aspect Ratio. Stresses in the vertical direction.

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18 Figure III.3 SX Stress Results 1:0.75 Aspect Ratio. Stresses in the horizontal direction. Figure III.4 SY Stress Results 1:0.75 Aspect Ratio. Stresses in the vertical direction.

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19 Figure III.5 SX Stress Results 1:0.66 Aspect Ratio. Stresses in the horizontal direction. Figure III.6 SY Stress Results 1:0.66 Aspect Ratio. Stresses in the vertical direction.

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20 Figure III.7 SX Stress Results 1:0.58 Aspect Ratio. Stresses in the horizontal direction. Figure III.8 SY Stress Results 1:0.58 Aspect Ratio. Stresses in the vertical direction.

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21 Figure III.9 SX Stress Results 1:0.50 Aspect Ratio. Stresses in the horizontal direction. Figure III.10 SY Stress Results 1:0.50 Aspect Ratio Stresses in the vertical direction.

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22 Figure III.11 SX Stress Results 1:0.33 Aspect Ratio Stresses in the horizontal direction. Figure III.12 SY Stress Results 1:0.33 Aspect Ratio Stresses in the vertical direction.

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23 Figure III.13 SX Stress Results 1:0.25 Aspect Ratio Stresses in the horizontal direction. Figure III.14 SY Stress Results 1:0.25 Aspect Ratio Stresses in the vertical direction.

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24 Results Fixed Against Rotation Results were very similar to simply supported resul ts, changes were often were only a few psi difference. This is attributed to th e stiffness of the panel, which rotates and deflects so little that results vary only slightly. Figure III.15 SX Stress Results 1:1 Aspect Ratio. Stresses in the horizontal direction.

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25 Figure III.16 SY Stress Results 1:1 Aspect Ratio. Stresses in the vertical direction. Figure III.17 SX Stress Results 1:0.75 Aspect Ratio Stresses in the horizontal direction.

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26 Figure III.18 SY Stress Results 1:0.75 Aspect Ratio Stresses in the vertical direction. Figure III.19 SX Stress Results 1:0.66 Aspect Ratio Stresses in the horizontal direction.

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Figure III.20 SY Stress Results 1: Stresses in the vertical direction Figure III.21 SX Stress Results 1: Stresses in the horizontal direction Stress Results 1: 0.66 Aspect Ratio. Stresses in the vertical direction Stress Results 1: 0.58 Aspect Ratio. Stresses in the horizontal direction 27

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28 Figure III.22 SY Stress Results 1:0.58 Aspect Ratio Stresses in the vertical direction. Figure III.23 SX Stress Results 1:0.50 Aspect Ratio Stresses in the horizontal direction.

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29 Figure III.24 SY Stress Results 1:0.50 Aspect Ratio Stresses in the vertical direction. Figure III.25 SX Stress Results 1:0.33 Aspect Ratio Stresses in the horizontal direction.

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30 Figure III.26 SY Stress Results 1:0.33 Aspect Ratio Stresses in the vertical direction. Figure III.27 SX Stress Results 1:0.25 Aspect Ratio Stresses in the horizontal direction.

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31 Figure III.28 SY Stress Results 1:0.33 Aspect Ratio Stresses in the vertical direction. Results Fixed End Beam of One Course Beam deflection varied between .060in for a 10ft c lear span to 0.955in for a 20ft clear span. Based on the analysis deflection under selfweight alone may be a significant contributor to masonry fence delamination for panel s in excess of 12ft in length. Figure III.29 10ft beam deflection. Figure III.30 12ft beam deflection.

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32 Figure III.31 14ft beam deflection. Figure III.32 16ft beam deflection. Figure III.33 18ft beam deflection. Figure III.34 20ft beam deflection.

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33 CHAPTER IV HYPOTHESIS Background Delamination of a masonry fence must have a combina tion of three distinct events to occur: the formation of a crack, the propagation of the crack along bed joints in the panel, and a mechanism which allows this cracked jo int to open significantly creating large deflections. The following hypotheses are off ered by the author for fence delamination, further discussed below. Hypothesis 1 Behavior of the panel is such that stresses initiat e a crack in the bed joints at the bottom of the panel, which continues to propagate. A finite element study was conducted to determine the validity of this hypothesis. For r esults see Chapter IV of this thesis. Finite element modeling results indicated that the panel could develop arching action and that the center and bottom of the panel was subject to tension both vertically and horizontally. Horizontal tension is likely the result of flexure, and vertical tension the result of self-weight of the panel spanning between supports. Results of the finite element model study indicate that horizontal stresses due t o flexure can ranges from 82 to 29psi for the 12ft clear spans and aspect ratios of 1:1 t o 1:0.25. Vertical tension stresses were not greater than 7psi for 12ft clear span all aspec t ratios. Stresses are assumed to increase with longer spans which are common in masonry fence design.

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34 The literature indicates large variations in actual tests of tensile bond strength between masonry units and mortar shows, with values ranging from 30 to 250psi (Dysdale and Hamid 2008). All vertical tension stre sses from the finite element analysis were less than the lower bound value of tensile str ength based on testing. Based on results from the finite element study along with testing re sults the author concludes that vertical tension stresses resulting from self-weight in the panel are unlikely to initiate a crack in the fence panel. Hypothesis 2 Many fence panels exhibit excellent performance ind icating good construction practices, and good workmanship. However, because d elamination occurs inconsistently and especially next to panels which are performing well, construction errors cannot be ruled out. The author hypothesizes that a variety o f construction errors may initiate the formation of a crack which will ultimately propagat e and contribute to fence delamination. Because masonry fences walls are built without a fo undation under the panel, they must be shored during construction. Shoring may var y, including sand beds, void forms, and lumber. Because panels are often constructed qu ickly, any disturbance in the foundation support could cause a disbonding between units creating a crack. Disturbances during construction may also inhibit the formation of arching in the panel (Drysdale and Hamid 2008). Delaminated masonry fences have been observed by th e author with corroded joint reinforcement and cracked bed joints in the s agging courses. Corrosion is likely

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35 from insufficient cover on the reinforcement, or us ing joint reinforcement which is not galvanized. Swink (Swink 2014) considers this a maj or cause of deterioration in panels. Figure IV.1 Cracking of bed joints due to corrosion of joint reinforcement. Photo courtesy of John Swink. Used with permission. Poor workmanship is known to affect many of the qua lities of masonry walls, including reduced strength and flexural capacity (D rysdale and Hamid 2008). Poor workmanship may manifest itself in multiple ways in cluding but not limited to breaking the bond of a unit that has been set, insufficientl y filled joints due to deep furrowing, rocking of bricks to square up the wall, or quality control issues (Drysdale and Hamid 2008). Any construction or workmanship error which has the potential to disturb the bond or produce a poor bond may be a contributing f actor that causes delamination. Swink (Swink 2014) recommends the construction of t est fence panels with no supporting shelf angle or beam at the bottom. Upon completion the support is removed, bricks which detach from the panel and fall are an indication of poor workmanship.

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36 Hypothesis 3 The author hypothesizes that a load sharing mechani sm between the panel and the beam forms upon crack initiation and loads transfer red to the beam near the supports cause the crack to propagate and facilitate delamin ation. Past research has been conducted on the composite a ction between reinforced concrete beams and masonry panels subjected to thei r own weight and additional applied loads (Wood 1952). For beams which are very stiff, the panel acts like an uniform load on the beam, and conversely for beams which are not very stiff relative to the panel, the panel carries nearly all of its weight from arching and the beam attracts very little load (Drysdale and Hamid 2008). Between these two extrem es both beam and panel carry part of the total load especially at the contact zones n ear the supports. Testing by Wood showed peak stresses in the beam from arching in th e panel were found in the clear span of the beam near the supports as shown in the figur e below. Figure IV.2 Load distribution on beam supporting br ick cavity wall. Photo from Woods 1952. Used with permission.

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37 In addition to determining the relationship between panel and beam stiffness Wood noted that there existed a loss of contact bet ween beam and panel near midspan. Drysdale and Hamid note that as this loss of contac t becomes large, beams tend to sag away from the panel as shown in Figure IV.3. Figure IV.3 Loss of contact between beams and mason ry panels. Adapted from Drysdale and Hamid 2008. The goal of previous research (Wood 1952) was prima rily concerned with economizing both reinforcement and beam geometry, n ot with explaining load paths which may lead to cracking in panels and increased deflections (beyond self-weight alone) in beams. This is an important distinction. The end goal of previous research is to rationally reduce the geometry (and therefore mater ials) required to still achieve adequate performance. The author of this thesis is intereste d in understanding how this composite action may contribute to the separation and deflect ion of a beam which was never intended to become a discrete element and was not d esigned to behave as such.

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38 Hypothesis 4 Once a crack initiates, the panel begins to form tw o separate discrete elements, the upper remaining panel, and the separated course or courses. It is hypothesized that the self-weight of the separated course or courses alon e deflects enough to cause delamination. To test this hypothesis several finite element mode ls of a single beam with fixed ends but allowed to translate subjected to its own self weight. The results of this study are available in Chapter III of this thesis. Simply sup ported beams were not considered. Wood (Wood 1952) noted that upon construction of ma sonry panels on beams designed as simply supported, beams were restrained from rot ating at their ends due to the presence of compressive loads from the above suppor ted masonry. Thus the behavior of beams is such that they are restrained from rotatio n regardless of the intent of the designer. Observationally this has been confirmed i n pictures of delaminated masonry fences. According to analysis, a single course of masonry f ixed against rotation at both ends spanning a distance of 12ft will deflect under its own weight approximately 0.124in. In longer spans deflection becomes more pronounced. A span of 20ft produces a deflection of 0.955in. The remaining fence panel de flects very little relative to the detached beam, so even deflections that are less th an code required span/600 (TMS 2011) become quite visually obvious. In panels greater th an 12ft in length this may be a contributing factor to fence delamination.

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39 Hypothesis 5 Once a crack fully propagates across the panel the lower courses are able to separate from the panel forming a discreet beam. Be cause of the high compressive stresses at each end of the panel the behavior of t his beam tends to be fixed against rotation and the highest flexural stresses are now at the ends of the beam. The author hypothesize that insufficiently developed reinforce ment is subjected to a bond failure at these locations with the grout failure allowing the beam to displace and delaminate. Fence panels that terminate at a pier or which are not designed with continuous reinforcement through the pier are assumed to have simply supported boundary conditions. Design literature recommends for this s upport condition to design panels as deep beams using a strut and tie method similar to reinforced concrete (Drysdale and Hamid 2008). Tension reinforcement is assumed to ac t as tie for flexural stresses in the panel. Fence panels are usually constructed of cored brick s of standard sizes which lack the ability to be readily reinforced vertically, du e to insufficient cell size of the cores, and the inability of the cores to align vertically when bricks are laid in running bond. Accordingly, reinforcement in the bond beam simply terminates at the end of the panel and is without an upwards hook. Reinforcement is de veloped beyond the clear span of the panel only the length that the panel extends into t he pier, which is usually only a few inches. If the designer has attempted to provide co ver around the end of the reinforcement this distance is reduced further stil l, and may in reality be 2 inches or less. During the test of the specimen, described in Chapt er VII, both ends of the grouted bond beam exhibited a bond failure where th e grout shattered and allowed the

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rebar to move freely and the panel to deflect much more than pre may help explain the very large displacements that accompany delamination in some fences. Figure IV.4 Detail of reinforcement detailing. rebar to move freely and the panel to deflect much more than pre viously anticipated. This may help explain the very large displacements that accompany delamination in some Detail of reinforcement detailing. 40 viously anticipated. This may help explain the very large displacements that accompany delamination in some

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41 CHAPTER V OBJECTIVE OF STUDY The objective of this study was to prove or dispro ve one of five hypotheses suggested as a cause of delamination in Chapter V o f this thesis. The fence panel delamination seen in Figure IV.1 was the basis of t he experiment. Based on the picture the author surmises the panel is constructed of kin g sized units 9.875in in length and with a height of 2.75in and standard 0.375in joints. Th ere panel is 13 units wide and 24 courses high with approximate dimensions of 11ft by 6.25ft and an aspect ratio of 0.57. The delaminated course has come to rest on the conc rete below and has deflected a about of the height of one course of masonry, approximate ly 2.75in. There appears to be a zone near the supports where cracks do not extend and a length of contact remains. Figure V.1 Masonry Fence Panel showing delamination Photo courtesy of Atkinson-Noland & Associates. Use d with permission.

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42 The delaminated fence panel shown in the figure wa s selected as the basis of the experiment. Results from the finite element study i n Chapter III indicate that at similar aspect rations and spans (1:0.58, 12ft span) tensio n stresses are unlikely to initiate a crack on their own. This eliminates hypothesis 1. Without a set of design drawing or being able to ex amine the wall in person it is not possible to determine if there is a constructio n error (Hypothesis 2). Additionally, if a construction error was the cause of crack formation and propagation it does not explain the large deflection of the bottom course. Given the span of the fence panel in the picture, a nd results from the finite element study indicate that deflection of the detac hed beam due to selfweight alone would not produce such obvious deflection, effectiv ely ruling out hypothesis 4. Of the remaining hypothesis proposed the cause is likely e ither Hypothesis 3 or Hypothesis 5. Thus the object of this thesis would be to determin e to what extent a load sharing mechanism exists in a pier and panel fence.

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43 CHAPTER VI EXPERIMENT DESCRIPTION An experimental panel was designed and constructed with the goal testing Hypothesis 3 and to observe the extent of arching o f the panel and length of contact (if any) between the panel and the beam. A masonry pane l of similar length and aspect ratio was built. The experimental panel was designed to h ave a clear span of 12.0ft and a minimum height of 7.0ft with an aspect ratio of 0.5 8. The reinforcement in the bottom bond beam was designed using the strut and tie proc edures for reinforced concrete as recommended by Drysdale and Hamid (Drysdale and Ham id 2008). To facilitate rapid observation of the behavior of the panel, it was constructed of dry stacked masonry over a single reinforced masonr y beam. The assumed behavior would be for the panel to develop arching and the b eam to carry its own weight and a small triangular load of masonry. The author was un sure if there would be any contact zone between the masonry which formed the arch in t he panel and the beam, or the length of such a contact zone. Similar to actual pier and panel walls the panel was constructed the experimental panel was built with a removable s and support between two discreet brick piers. Because the experimental panel was lai d as a dry stacked panel, formwork was used to ensure stability. The formwork was cons tructed of lumber braces and plywood brace for the back of the panel, and lumber braces with acrylic sheets that were installed as the experimental panel was constructed The acrylic sheets were utilized to permit viewing of the panel behavior as the sand su pport was removed.

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44 Construction of Piers The piers were constructed out of king sized brick with a recessed pocket similar to piers in a regular pier and panel wall. However, because the piers were not connected structurally to a foundation, they were designed to resist overturning and sliding by their mass alone. Each pier was designed to have a factor of safety against both sliding and overturning of 1.5. The overturning load governed d esign. Each pier was designed to resist a lateral load of 200 lbs at a height of 5ft in either direction. 200 lbs was selected as this is the minimum design lateral load for a hand rail post in ASCE 7 (ASCE 2010). When considering both the geometric and stability r equirements, the resultant pier was a total height of 8ft with a 21.5in by 20.13in base w hich tapered to 9in by 21.13in at the top. Figures VI.1 through VI.7 show the constructio n of the piers in various stages. Figure VI.1 Mixing of mortar with sand.

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45 Figure VI.2 Addition of water to achieve desired co nsistency. Figure VI.3 Construction of the first pier.

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46 Figure VI.4 First pier nearing completion. Figure VI.5 Construction of second pier commencing.

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47 Figure VI.6 Construction of the second pier. Note the quantity of specially cut bricks used to g radually taper the pier. Each pier was gradually tapered a half brick width every two courses until the final width of 9in was achieved. To accomplish this bricks were cut lengthwise in 0.25, 0.5, and 0.75 widths. This was a very time consumin g process.

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48 Figure VI.7 Second pier nearing completion. Construction of Wood Formwork Wooden formwork was designed with two goals in min d, to provide an attachment point for either the plywood brace or ac rylic viewing sheets, and to restrain any incidental lateral loads of the dry stacked mas onry panel as the sand support was removed. Each wood form was designed to be 8.75ft. high and 4ft in length. A total of eight were required, four on each side. Each brace was designed to provide a 9in space between the bottom of the plywood or acrylic and th e ground. This space was occupied by the formwork which held the sand. Figures VI.8 t hrough VI.15 show construction of the wood formwork and plywood brace.

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49 Figure VI.9 Construction of wood form. Figure VI.10 Detail of wood form with stringers. Stringers provide clearance for removable sand supp ort.

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50 Figure VI.11 Installation of first plywood sheet. Figure VI.12 Installation of second plywood sheet.

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51 Figure VI.13 Completed plywood brace installed. Figure VI.14 Installation of the removable sand sup port. Each sand support was held together with screws all owing them to be quickly dismantled.

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52 Figure VI.15 Removable sand support installed. Construction of Bond Beam Each bond beam was constructed of individually cut king size bricks. Calculations from the strut and tie model showed that a #3 bar w ould provide sufficient area to act as the tension tie. The size and strength of the reinf orcement was verified by inspection of the marking on the bar. Grout for the bond beam was specified according to the procedures of ASTM C476 (ASTM 2009) and testing acc ording to the procedures of ASTM C1019 (ASTM 2013). Table VI.1 contains the mix proportions for the fine grout used in the bond beam. Water was added until the de sired slump of 9in was achieved.

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53 Table VI.1 Fine Grout Mixture Proportions. Material Specific Gravity Density [lbs/ft3] Mix Proportion [lbs] Portland Cement -Type II 3.15 196.6 49.1 Sand ASTM C33 2.69 167.9 104.9 Hydrated Lime Type S 2.40 149.8 3.7 Water 1.00 62.4 23.0 To ensure that grout was of adequate strength three grout cubes were constructed and tested for their seven day strengths. Seven day strengths were chosen because many masonry fences are constructed in just a few days a nd the forms removed upon completion of construction. Table VI.2 contains the seven day strength test results. The average compressive strength was approximately 6,94 0psi. Table VI.2 Grout Cube Strength Test Results. Sample Number Length [in] Width [in] Height [in] Area [in2] Failure Load [lbs] Compressive Strength [lbs/in2] 1 3.55 3.25 7.1 11.54 85,526 7,413 2 3.25 3.25 6.5 10.56 74,318 7,036 3 3.40 3.70 6.8 12.58 79,993 6,359

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54 Figure VI.16 Reinforcing steel markings. Marks on reinforcement are follow guidance given in ASTM A615 (ASTM 2014). Figure VI.17 Bond beam prepared for grouting.

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55 Figure VI.18 Detail of bond beam bricks and reinfor cing steel. Figure VI.19 Preparations made for grout prism pour s.

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56 Figure VI.20 Detail of grout prism form prior to po uring of grout. Figure VI.21 Grout prim filled with fresh grout. Photo courtesy of Katie Bartojay. Used with permiss ion.

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57 Figure VI.22 Bond beam with reinforcement fully gro uted. Figure VI.23 Detail of left end of bond beam. Grout extended the full length of the beam, ensurin g good bond of the reinforcement.

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58 Figure VI. 24 Detail of right end of bond beam. Figure VI.25 Grout prism prepared for testing. Grout prism hard capped and prepared for compressiv e strength testing. Photo courtesy of Katie Bartojay. Used with permission.

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59 Figure VI.26 Testing of grout prism. Photo courtesy of Katie Bartojay. Used with permiss ion. Construction of the Panel and Dry stack Acrylic She ets Upon curing of the bond beam grouting, the panel w as built by stacking king sized bricks on top of each other for a total of 30 courses. As each successive 8 courses were built an acrylic viewing sheet with wood tabs was installed and secured to the wooden forms. Between both the acrylic sheets and p lywood brace the bricks were free to move any direction in plane but were restrained fro m out of plane movement. Figure VI.31 shows an end view of the bricks sandwiched be tween acrylic sheets and plywood form to better illustrate the restraint of out of p lane movement. During the course of laying the courses of masonry a deflection of appro ximately 0.5 inch occurred which was

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60 attributed to spreading of the removable sand suppo rt wood. Exact dimensions of the constructed experimental panel were 11.96ft by 7.03 ft. Figure VI.27 Laying the first few courses of masonr y. Figure VI.28 Approximately 5 ft of masonry laid.

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61 Figure VI.29 Completion of the experimental panel. Figure VI.30 The completed experimental panel Photo courtesy of Frederick Rutz. Used with permiss ion.

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62 Figure VI.31 Masonry sandwiched between plywood bra ce and acrylic sheets. Photo courtesy of Frederick Rutz. Used with permiss ion. Figure VI.32 Expansion joint. Several inches ensured no restraint. Photo courtesy of Frederick Rutz. Used with permission.

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63 Figure VI. 33 Tape on acrylic sheets. Tape was used to help measure deflections. Photo co urtesy of Frederick Rutz. Used with permission. Figure VI.34 Detail of Tape on acrylic sheets. Tape was placed at the top of each course for the f irst 10 coursed and then every other course thereafter. Photo courtesy of Fredrick Rutz. Used with permission.

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64 Figure VI.35 Awaiting removal of sand support. Frederick Rutz at left and author at right. Photo c ourtesy of Frederick Rutz. Used with permission.

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65 CHAPTER VII TEST RESULTS The testing phase of the experiment began with the removal of the sand support as shown in Figures VII.1 and VII.2. Upon removal of t he fence support by releasing the sand, the field of loose-laid brick settled downwar d. A noise accompanied this settlement at which time the photograph in Figure VII.3 was ta ken. The single course reinforced element began to sag under the weight of the looselaid brick. Deflections were observed only in the middle of the panel, the ends of the pa nel moved little if at all. Based on this initial observation the expansion joints appeared t o be effective in that no brick hung-up in them, thus the panel was free to translate horiz ontally, subject to friction of brick on the support only, and was free to rotate in-plane. Additionally it was confirmed that no brick hung up on either the plywood form, or the ac rylic sheets. Figure VII.1 Removal of sand support. Photo courtesy of Frederick Rutz. Used with Permiss ion.

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66 Figure VII.2 Detail of sand support removal. Photo courtesy of Frederick Rutz. Used with Permiss ion. Figure VII.3 Panel behavior after during sand remov al. Sand was removed in stages; panel behavior after so me support has been removed.

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67 More sand was removed, and the panel continued to s ag. Stair-step joint separations occurred, originating at the supports a nd at an angle of approximately 40 degrees, however full arching never occurred. A re verse curvature was observed at all dry stack courses and also the bond beam. As more s and was removed from under the bond beam, bond failures between the rebar and grou t occurred, allowing further displacement of the beam and the panel. The exact t ime of these bond failures occurred was uncertain and only discovered later. At this in termediate stage of removal, the photograph in Figure VII.4 was taken. Displacement was approximately 5in in this photo. Figure VII.4 Panel behavior after removal of sand. Panel behavior after all sand removed, but resting on wood shims. All sand and lumber was removed and the bottom of the bond beam and panel came to rest on the ground. Overall deflection of t he bond beam approximately 10.12 inches. The final behavior of the panel can be seen in Figures VII.5 through VII.9.

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68 Figure VII.5 Final panel behavior. All sand and wood shims removed, panel rests on the ground. Figure VII.6 Detail of bond beam at left pier suppo rt. Upon dismantling the panel a rebar bond failure was found at this location. Photo courtesy of Frederick Rutz. Used with permission.

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69 Figure VII.7 Detail of left end of panel at pier su pport. Photo courtesy of Frederick Rutz. Used with permiss ion. Figure VII.8 Detail of deflection at the bottom cen ter of the panel. Deflection was greater than 10in at this location.

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70 Figure VII.9 Detail of deflection at the top center of the panel. Deflection was greater than 7in at this location. During the disassembly of the experiment the loose laid brick was removed course by course. Despite a continual reduction of the load on the bond beam, no deflection was recovered. Once all loose laid brick was removed, the exposed bond beam revealed that there was a bond failure between the rebar and grout at both the ends. The grout had shattered apart and the rebar was complet ely separated from the grout and unconnected to the masonry units. Figures VII.10 an d VII.11 shows both ends of the bond beam during disassembly revealing the masonry grout and rebar bond failure. Behavior of the panel was different than had been e xpected. It was assumed that some form of complete arching would occur, but this never fully came about. Stair stepping and arching action was most prominent lowe r in the panel and near the supports, presumably where compressive stresses were higher a nd units did not move separately from one and other. While complete arching is possi ble in a dry stacked wall, it likely

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71 would require higher compressive stresses, an effec tive tension tie, or support conditions that could receive horizontal thrust, which transla tes to a higher wall or lateral restraints and ends of the panel. Finite element modeling capt ures linear elastic behavior but not slip and separation between units. Figure VII.10 Detail of reinforcement bond failure at left end of panel.

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72 Figure VII.11 Detail of reinforcement bond failure at right end of panel. Despite leaving several inches of space for the pan el to translate and not restraining rotation at either end, the panel faile d to deflect in single curvature and instead exhibited double curvature at both the top and the bottom of the panel. The bond beam was also subject to a fixed condition, the compress ive stresses from the above panel were sufficient to prevent rotation of the ends of the b eam. This would shift the highest bending moments to the edges of the bond beam, and likely led to the rebar grout bond failure in the beam due to insufficient development length. The ends of the bond beam were the only areas to exhibit this failure. This f ailure was not anticipated during the conception of the experiment.

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73 CHAPTER VIII CONCLUSION While the outcome was unanticipated, the author be lieves that the experiment was setup to adequately test the panel w ith similar conditions to what is experienced in the field; i.e. completion of the pa nel, sufficient room to allow the panel to deflect longitudinally. The formwork and acrylic al lowed viewing of the behavior as it unfolded. Based on the deflection of the bond beam it seems unlikely that a load sharing mechanism as proposed in hypothesis 4 exists. While dry stacked panels allow for visually observa ble behavior they leave something to be desired in terms of predicting resu lts with commercially available finite element software. Additionally they may require muc h more depth to achieve actual arching then in a continuous panel. Because of the se limitations their use in future research should be considered carefully, and perhap s experimented with at a smaller scale, or altogether abandoned. The observance of a bond failure between the reinfo rcement and grout was unexpected and highlights a potential problem that warrants more investigation. The author hypothesizes that this was a result of insuf ficient development length of the rebar in a region of high negative moment. In masonry fen ces that terminate at piers or have expansion joints without continuous reinforcement t he development length of the reinforcement is often only the length that the pan el has in bearing on the pier. This length is often much less than required to develop the capacity of the bar. This observation was the basis of hypothesis 5.

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74 The author believes the experiment did demonstrate that joint delamination did not occur for loose laid brick with good expansion joints at each end, and concludes that functional expansion joints contribute to the avoid ance of fence delamination. Because of the lack of full arching and rebar bond failure the hypothesis could not be tested completely. The cause of the masonry dela mination in single-wythe fences remains uncertain at this time. Further research is recommended on a variety of fro nts with respect to these fences: Pre-determining the formation of a crack in the pan el by constructing a fully mortared panel with no bed joint between the bond b eam and the rest of the panel to observe if any delamination will occur would be a g ood start. This should be considered carefully, ensuring that adequate development lengt h exists on either side of the clear span of the panel as not to introduce any additiona l variables into the experiment. The aforementioned experiment could also be repeate d with a variety of different bearing and development lengths to determine if end support conditions and detailing are a contributing cause of these delaminations. The experiment could be repeated by removing both e xpansion joints which would prevent any lateral translation in the panel. This may more readily facilitate arching to occur in panels than those without expan sion joints. Where delaminated panels are in the process of bein g repaired by being rebuilt, observing the bottom courses of the panels before t hey are demolished may lead to a better understanding of the underlying causes of de lamination.

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76 REFERENCES ASCE. (2010). “Minimum Design Loads for Buildings a nd Other Structures.” ASCE Standard ASCE/SEI 7-10, Reston, VA. ASTM. (2009). “Standard Specification for Grout for Masonry.” ASTM C476-09 West Conshohocken, PA. ASTM. (2013). “Standard Test Method for Sampling an d Testing Grout.” ASTM C101913 West Conshohocken, PA. ASTM. (2014). “Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement.” ASTM A615-14 West Conshohocken, PA. BIA. (1995). Technical Note 45A – Brick Masonry Noise Barrier Wa lls – Structural Design, Reston, VA. BIA. (2001). Technical Note 45 – Brick Masonry Noise Barrier Wal ls – Introduction, Reston, VA. Drysdale, R., and Hamid, A. (2008). Masonry Structures Behavior and Design 3rd Edition, The Masonry Society, Boulder, Colorado. FHWA. (2000). “FHWA Highway Noise Barrier Design Ha ndbook.” FHWA-EP-00-005, Cambridge, MA. Hughes, R. (2012). Rome: A Cultural, Visual, and Personal History, Vintage Books, New York, NY. Schuller, M., Woodham, D., and Travers, D. (2007) Masonry Sound Barrier Walls and Fences, Rocky Mountain Masonry Institude: Denver 2007. Swink, J. (2014). “Single-wythe Brick Panel Fence F ailures.” Structure Magazine, June 2014, 29-30. TMS. (2011). “Building Code Requirements and Specif ication for Masonry Structures.” TMS 402-11, Boulder, CO.

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77 Wood, R.H. (1952). “Studies in Composite Constructi on Part I. The Composite Action of Brick Panel Walls Supported on Reinforced Concrete Beams” National Building Studies Research Paper No. 13, 1-25.