The research described here is part of a multi-university project on “Performance-based Seismic Design Methods and Tools for Reinforced Masonry Shear-Wall Structures.” Within the context of that project, the objective of the research described in this dissertation was to develop and validate a specific displacement-based seismic design methodology for masonry structures. Experimental work consisted of reversed cyclic loading tests of reinforced masonry wall segments with different boundary conditions, aspect ratios, axial loads, and reinforcement detailing. Analytical work consisted of developing analytical models for in-plane concrete masonry shear wall segments; calibrating those models using reversed cyclic test data; and using those models to successfully predict the nonlinear seismic response of two full-scale, multi-story reinforced masonry specimens tested on the shake-table at the University of California at San Diego. Design work consisted of the force-based and displacement based design of those specimens. Based on the results, provisions for displacement-based seismic design are proposed for inclusion in United States design codes. / text

Submitted by Regina Correa (rehecorrea@gmail.com) on 2016-09-09T19:49:38Z No. of bitstreams: 1 DissRDP.pdf: 6790691 bytes, checksum: b888125fd30db642f17445cce46fe74c (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-13T14:55:38Z (GMT) No. of bitstreams: 1 DissRDP.pdf: 6790691 bytes, checksum: b888125fd30db642f17445cce46fe74c (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-13T14:56:11Z (GMT) No. of bitstreams: 1 DissRDP.pdf: 6790691 bytes, checksum: b888125fd30db642f17445cce46fe74c (MD5) / Made available in DSpace on 2016-09-13T14:56:58Z (GMT). No. of bitstreams: 1 DissRDP.pdf: 6790691 bytes, checksum: b888125fd30db642f17445cce46fe74c (MD5) Previous issue date: 2015-02-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / This study intends to analyze, in the construction system that is in ascendancy - the structural masonry, an element that demands a special attention comparing to other elements: the reinforced concrete masonry beam. The beams carry vertical loads, with flexure and shear forces. In the theoretical part, the literature review included national and international papers and codes. The assessed codes were the national (NBR15961-1/2011 and NBR 6118/2014) and international (ACI530-13, AS3700/2001, S304/2014 and Eurocode 6.1/2001). The experimental study includes testing of ten (10) concrete block masonry beams, designed to fail due to shear forces. As a conclusion, it can be pointed that concrete masonry beams failure in a similar behavior to concrete beams, except for some particularities such as prior joint cracking. Furthermore, the specification at Brazilian and European standards led to considerably higher results than the experimental results while the specifications at ACI530-13, AS3700/2001, S304/2014 and NBR6118/2014 yielded reasonable predicted values when compared to experimental results. / O presente trabalho busca analisar, dentro de um dos sistemas construtivos que está em ascendência, que é a alvenaria estrutural, um dos elementos estruturais que necessita de uma atenção maior quando comparado com os demais: a viga de alvenaria armada com blocos de concreto. Vigas apresentam carregamento vertical e são submetidas a flexão e cisalhamento, sendo esse último esforço o tema desta pesquisa. Na parte teórica, foram considerados trabalhos anteriores, tanto nacionais quanto internacionais, e as prescrições das normas brasileiras NBR15961-1/2011 e NBR 6118/2014, além das norte-americanas ACI530/2013 e ACI530/2013, a australiana AS3700/2001, a canadense S304.1/2014 e a europeia EuroCode 6.1/2001. Com intuito analisar e validar as especificações da literatura, foi realizado programa experimental de análise de dez vigas de alvenaria com blocos de concreto submetidas principalmente ao esforço cortante. Como conclusão, verificou-se semelhanças no comportamento último das vigas de alvenaria armada com a teoria proveniente das vigas de concreto armado, com algumas particularidades de fissuração na região das juntas de argamassa. Além disso, as especificações estabelecidas pelas normas brasileira e européia levaram a resultados consideravelmente maiores do que os resultados experimentais, enquanto que as presentes nas normas ACI530/2013, AS3700/2001, S304.1/2014 e NBR6118/2014 levam a resultados próximos aos obtidos experimentalmente.

Emendas por traspasse são criadas pela justaposição de barras de aço em um determinado comprimento, assegurando que elas se manterão em posição. Assim como em outros sistemas estruturais, a alvenaria estrutural de blocos de concreto utiliza barras de aço como reforço dos elementos quanto à resistência à tração, mais proeminentes em edifícios altos devido à ação dos ventos. As armaduras são projetadas para serem alocados no interior dos blocos, e a prática construtiva no Brasil é posicionar as armaduras de aço antes dos blocos serem assentados. Devido à essa prática, as paredes precisam ser construídas em pelo menos duas etapas, para considerar a altura limite imposta pela armadura posicionada ao operário na elevação dos blocos. Para aumentar a eficiência na elevação das paredes de alvenaria, hélices circulares são propostas como componentes de confinamento do graute que envolve a emenda, permitindo a elevação da parede em etapa única. A armadura é colocada dentro da seção transversal da espiral após a parede de alvenaria ser completamente elevada. O objetivo desta investigação é avaliar a eficiência da emenda por traspasse, com hélice circular atuando como componente do confinamento do graute que envolve a emenda. Quatro configurações de emenda distintas foram ensaiadas: a primeira, referência, foi justaposta e amarrada com arame; a segunda foi espaçada, porém sem a presença de um componente de confinamento; a terceira foi espaçada e continha uma hélice circular com passo de 3,5 cm; e a quarta foi espaçada e continha uma hélice circular com passo de 8,0 cm. Os ensaios permitiram concluir que a hélice de traspasse é um componente eficiente no confinamento das emendas por traspasse em alvenaria estrutural de blocos de concreto. Análises estatísticas dos resultados demonstram que emendas por a emenda com hélice circular de 3,5 cm não só é equivalente à emenda por referência do ponto de vista da resistência à tração, como também contribui para a redução de fissuras. / Lap slices are created by the overlapping of reinforcement bars over a specified length and reassuring that they stay in place. As with other structural systems, concrete block masonry uses reinforcing steel to carry the tensile loads which are more prominent on tall buildings due to the effect of wind. Reinforcing bars are designed to be placed inside block cells. The construction practice in Brazil is to place the reinforcing steel before the block units are laid. With this practice, walls need to be built in at least two lifts to account for the height limits imposed by the mason having to lift each block over the reinforcing bars. To increase the efficiency of wall construction, spirals are proposed as confinement components of the grout surrounding the lap splices, allowing a single-lift wall construction. The vertical reinforcement is then placed inside the cross-section of the spiral after the laying of blocks is complete. The objective of this investigation is to evaluate the efficiency of lap splices with spirals as confinement components of grout. Four types of single-bar splice specimens were prepared during the test program consisting of: first, contact lap splices tied by steel lock wires; second, non-contact lap splices without any confinement components; third, non-contact lap splices with the surrounding grout confined by spirals with 35 mm pitch; fourth, non-contact lap splices with the surrounding grout confined by spirals with 80 mm pitch. The results of the experimental program show that spirals are efficient confinement components of non-contact lap splices in concrete block masonry. Statistical analysis of results demonstrate that non-contact lap splices confined by spirals with 35 mm pitch are not only equivalent with contact lap splices regarding their ultimate tensile resistance, but also contribute to the reduction of cracks.

Well-detailed reinforced concrete (RC) shear walls did not achieve the expected seismic performance in the 2011 Christchurch earthquake as per the Canterbury earthquake royal commission report. Similarly, RC shear walls showed low seismic performance in the 2010 Maule earthquake. The two major seismic events intrigued this research dissertation, where six half-scaled RC shear walls were constructed and tested. The six walls were split into two phases, each phase had different end configurations (i.e., rectangular, flanged, and boundary elements). Phase II RC walls had 2.4 times the vertical reinforcement ratio of Phase I walls. The walls were detailed as per CSA A23.3-19, and they were tested laterally under a quasi-static cyclic fully-reversed loading while maintaining a constant axial load through the full test of the walls. The overall seismic performance of the six walls is evaluated in Chapters 2 and 3 in terms of their load-displacement relationships, crack patterns, displacement ductility capacities, stiffness degradation trends, curvature profiles, end strains, energy dissipation capabilities, and equivalent viscous damping ratios. In addition, damage states are specified according to the Federal Emergency Management Assessment (FEMA P58) guidelines. The results came in agreement with the Canterbury earthquake royal commission report, where the test walls with low vertical reinforcement ratios showed lower-than-expected seismic performance due to the concentration of their plastic hinges at the primary crack locations. Moreover, the results validated the Christchurch (2011) and Maule (2010) earthquake findings as concentrating the rebars at the end zones and providing adequate confinement enhanced the seismic performance of the test walls, which was the case for Phase II flanged and boundary element walls. The displacement ductility variations of the test walls inspired the work of Chapter 4, where the objective is to develop a data-driven expression for RC shear walls to better quantify their displacement ductility capacities. In this respect, an analytical model is developed and experimentally validated using several RC walls. The analytical model is then used to generate a dataset of RC walls with a wide range of geometrical configurations and design parameters, including cross-sectional properties, aspect ratios, axial loads, vertical reinforcement ratio, and concrete compressive strengths. This dataset is utilized to develop two data-driven prediction expressions for the displacement ductility of RC walls with rectangular and flanged/boundary element end configurations. The developed data-driven expressions accurately predicted the displacement ductility of such walls and they should be adopted by relevant building codes and design standards, instead of assigning a single ductility-related modification factor for all ductile RC shear walls, as per the 2020 National Building Code of Canada. Several researchers tested well-detailed Reinforced Masonry (RM) shear walls and the results concluded that RM shear walls showed high seismic performance similar to that of RC shear walls. This intrigued the research efforts presented in Chapter 5, where a comparative analysis is performed between the six RC walls tested in this dissertation and three RM walls tested in a previous experimental program. The analysis focuses on comparing the seismic performance of both wall systems in terms of their crack patterns, load-displacement envelopes, curvature profiles, displacement ductility, normalized periods, and equivalent viscous damping ratios. In addition, an economic assessment is performed to compare such RC and RM shear walls using their total rebar weights and the total construction costs. Overall, RM shear walls achieved an acceptable seismic performance coupled with low rebar weights and low construction costs when compared to their RC counterparts. / Thesis / Doctor of Philosophy (PhD)

Reinforced concrete block shear walls (RCBSWs) are used as seismic force resisting systems in low- and medium-rise buildings. However, attributed to their nonlinear behavior and composite material nature, accurate prediction of their seismic performance relying only on mechanics is challenging. This study introduces multi-gene genetic programming (MGGP)— a class of bio-inspired artificial intelligence, to uncover the complexity of RCBSW behaviors and develop simplified procedures for predicting the full backbone curve of flexure-dominated fully grouted RCBSWs under cyclic loading. A piecewise linear backbone curve was developed using five secant stiffness expressions associated with cracking, yielding, 80% ultimate, ultimate, and 20% strength degradation (i.e., post-peak stage) derived through controlled MGGP. Based on the experimental results of large-scale cyclically loaded RCBSWs, compiled from previously reported studies, a variable selection procedure was performed to identify the most influential variable subset governing wall behaviors. Utilizing individual wall results, the MGGP stiffness expressions were first trained and tested, and their accuracy was subsequently compared to that of existing models employing various statistical measures. In addition, the predictability of the developed backbone model was assessed at the system-level against experimental results of two two-story buildings available in the literature. The outcomes obtained from this study demonstrate the power of MGGP approach in addressing the complexity of the cyclic behavior of RCBSWs at both component- and system-level—offering an efficient prediction tool that can be adopted by relevant seismic design standards pertaining to RCBSW buildings. / Thesis / Master of Applied Science (MASc)

<p>The increased public safety concerns to the consequences of deliberate and accidental explosions have led to the development of the Canadian (CSA S850- 12) and American (ASCE 59-11) blast standards. There is an urgent need to investigate and quantify the response of structural components under such extreme loading conditions. This is especially important for masonry components, where research has been limited due to the misconception that masonry (both reinforced and unreinforced) is an inadequate material for blast hardening applications. The standards allow the use of experimental testing or dynamic analysis in order to determine peak responses and evaluate them in terms of the code prescribed performance limits and accompanying levels of damage. The current study investigates the response of non-integral and non-participating infill walls designed to undergo two-way out-of-plane response and detailed to fail in flexure under static loading conditions. Through experimental blast testing and dynamic model validation of reduced-scale walls under a range of design-basis threat (DBT) levels, this study shows that reinforced masonry is a viable alternative for blast protection. However, the current flexural-based code requirements, thought to be conservative, may be inadequate at loads of higher impulse where shear damage is prevalent. This study also shows the influence that changing the boundary configuration and level of reinforcement has on the peak response, where the performance limits of the current codes makes no provisions for these parameters.</p> / Master of Applied Science (MASc)

Reinforced masonry (RM) shear walls are a common lateral load-resisting system for building structures. The seismic design guidelines for such systems are based on relatively limited experimental data. Given the restrictions imposed by the capabilities of available experimental equipment, analytical modeling is the only means to conduct systematic parametric studies for prototype RM wall systems and quantify the seismic safety offered by current design standards. A number of modeling approaches, with varying levels of complexity, have been used for the analysis of reinforced concrete (RC) and masonry wall structures. Among the various methods, the truss analogy is deemed attractive for its conceptual simplicity and excellent accuracy, as indicated by recent studies focusing on RC walls. This thesis uses an existing modeling method, based on nonlinear truss models, to simulate the behavior of fully grouted reinforced masonry shear walls. The modeling method, which was originally created and used for RC walls, is enhanced to capture the effect of localized sliding along the base of a wall, which may be the dominant mode of damage for several types of RM walls. The truss modeling approach is validated with the results of quasi-static cyclic tests on single-story isolated walls and dynamic tests on a multi-story, three-dimensional wall system. For the latter, the truss model is found to give similar results to those obtained using a much more refined, three-dimensional finite element model, while requiring a significantly smaller amount of time for the analysis. Finally, truss models are used for the nonlinear static analysis of prototype low-rise walls, which had been analyzed with nonlinear beam models during a previous research project. The comparison of the results obtained with the two modeling methods indicates that the previously employed beam models may significantly overestimate the ductility capacity of RM squat walls, due to their inability to accurately capture the shear-flexure interaction and the effect of shear damage on the strength of a wall. / Master of Science

Résumé : Cette juxtaposition de matériaux solides -blocs, pierres ou briques,...- liés ou non entre eux que nous appelons maçonnerie ne se comporte pas très bien vis-à-vis des forces latérales, surtout si elle n’a pas été réalisée suivant les normes parasismiques ou de façon adéquate. Cette vulnérabilité (glissement, cisaillement, déchirure en flexion, ou tout autre) vient souvent du fait même de ce processus d’empilement, des problèmes d’interaction avec le reste de la structure et aussi à cause des caractéristiques mécaniques peu fiables de certains éléments utilisés. Malgré cette défaillance structurale, la maçonnerie est encore utilisée aujourd’hui grâce à son côté traditionnel, sa facilité de mise en œuvre et son coût d’utilisation peu élevé. Depuis quelques années, la maçonnerie s’est enrichie de documents qui ont été publiés par divers chercheurs dans le but d’une meilleure compréhension des caractéristiques mécaniques des éléments et aussi, et surtout, des mécanismes de rupture des murs de maçonnerie pour une meilleure réponse face aux sollicitations sismiques. Beaucoup de programmes expérimentaux ont alors été effectués et tant d’autres sont encore nécessaires. Et c’est dans ce contexte que cette recherche a été conduite. Elle présentera, entre autres, le comportement sous charges latérales d’un mur en maçonnerie armée entièrement rempli de coulis. Ce projet de recherche fait partie d’un programme plus large visant à une meilleure connaissance du comportement sismique de la maçonnerie pour une amélioration des techniques de construction et de réparation des ouvrages en maçonnerie. / Abstract : This juxtaposition of solid materials -blocks, stones or bricks, ...- linked or not together called masonry does not behave very well towards lateral forces, especially if it has not been carried out according to seismic standards or enough adequate. This vulnerability - sliding, shearing, bending tear, or otherwise- comes often precisely because of this process of stacking, problems of interaction with the rest of the structure and also because of unreliable mechanical characteristics of used items. Despite this structural failure, masonry is still used today because of its traditional side, ease of implementation and low cost of use. In recent years, masonry was enriched with documents published by various researchers to a better understanding of the mechanical properties elements and also, above all, of the failure mechanisms masonry walls for a better response to seismic loading. Many experiences were then performed and many others are still necessary ; and therefore the Canada has for some time been involved in this adventure. And it is in this direction that goes this document. It presents, among others, the behavior under lateral loads of a reinforced masonry wall completely filled with grout. This research project is part of a broader program to a better understanding of the seismic behavior of masonry for an improvement of design and repair techniques of masonry.

The main goal of CIC-BREL project (Cracked and Inelastic Calculation of BRacing Elements) is to develop an analytical method to distribute horizontal forces on bracing elements, in this case reinforced masonry shear walls, of a building considering the cracked and inelastic state of material. The moment curvature curve of the wall section is created first depending on the section geometry and material properties of both the masonry units and steel reinforcement. This curve will start with an elastic material behavior, then continue in inelastic material behavior where the masonry crushes and the steel start to yield, until the maximum bending moment M_p is reached. Due to reinforced masonry wall ductility, post maximum capacity is also considered assuming a maximum curvature of 0.1%. From the moment curvature curve, the force displacement curve could be extracted depending on the wall height and wall boundary conditions. Matrix formulation has been developed for both elastic and damaged stiffness matrix, considering different boundary conditions. Fixed-fixed boundary condition which usually exists at the middle stories or last story with strong top diaphragm, fixed-pinned which is the case of the last story that has a relatively soft top diaphragm, and pinned-fixed in the first story case. Other boundary conditions could be considered depending on the degree of fixation on the wall both ends at the top and the bottom. The matrix formulation combined with the force-displacement curve which considers different material stages (elastic, inelastic, ductile post peak force) is used to define forces in each bracing element even after elastic behavior. After elastic phase of each wall the stiffness of the element will degrade leading to a less portion of the total lateral force; other elastic walls, i.e., stronger walls, will receive more portion of the total force leading to a redistribution of the total force. This process will be iterated until the total force is distributed on each bracing element depending on the wall section state: elastic, inelastic and ductile post-peak capacity. Flowcharts clearly will show this process. Finally, a Fortran code is developed to show examples using this method. The developed analytical method will be verified by the results of shake table tests held at the University of California in San Diego, USA. Last test performed in the year 2018 uses T-section reinforced masonry walls, subjected to shakings with increased intensity. The total applied force for each shaking could be defined depending on the structural weight and shaking intensity (acceleration). The damage and displacement at each intensity has been recorded and evaluated. Depending on these test results, the results of the analytically developed method will be compared and evaluated. Total system displacement at different lateral load values has been compared for analytical calculations and shake table tests; furthermore, each wall state at increased load has been compared, good agreement could be noticed.:Acknowledgement 5 1. Introduction 7 1.1. State of the Art 9 1.2. Elastic Formulae 9 1.3. Example, Elastic Calculation 12 1.3.1. Stiffnesses of the System 13 1.3.2. Torsion due to Eccentric Lateral Loading 14 1.3.3. Distribution of the Lateral Load on Wall “j” and Floor “i” 15 2. Force Displacement Curve of RM Shear Wall 19 2.1. Introduction 19 2.2. Cantilever Wall 19 2.2.1. Cantilever Elastic Wall 19 2.2.2. Cantilever Inelastic Wall 21 2.2.3. Cantilever Post-Peak Wall 22 2.3. Fixed-Fixed Wall 23 2.3.1. Fixed-Fixed Elastic Wall 23 2.3.2. Fixed-Fixed Inelastic Wall 24 2.3.3. Fixed-Fixed Post-Peak Wall 26 2.4. Moment – Curvature Analysis 26 2.5. Example, Rectangle Cross Section, Cantilever 29 a) Moment Curvature Curve 29 b) Force Displacement Curve 32 2.6. Example, Rectangle Cross Section, Fixed-Fixed 33 a) Moment Curvature Curve 33 b) Force Displacement Curve 33 2.7. Example, T Cross Section, Cantilever 35 a) Moment Curvature Curve 35 b) Force Displacement Curve 41 2.8. Example, T Cross Section, Fixed-Fixed 43 a) Moment Curvature Curve 43 b) Force Displacement Curve 43 3. Matrix Formulation 47 3.1. Procedure 47 3.2. Structure Discretization 47 3.3. Element, i.e.; Wall, Local Stiffness Matrix 48 3.4. Stiffness Matrix of Fixed-Pinned Beam 52 3.4.1. Elastic 52 3.4.2. Pre-Peak Inelastic 54 3.4.3. Post-Peak Inelastic 55 3.4.4. Normal Force Part in the Stiffness Matrix 56 3.5. Stiffness Matrix of Pinned-Fixed Beam 57 3.5.1. Elastic 57 3.5.2. Post-Peak Inelastic 57 3.6. Stiffness Matrix of Fixed-Fixed Beam 58 3.6.1. Elastic 58 3.6.2. Post-Peak Inelastic 60 3.7. Summary of Stiffness Matrices 61 3.7.1. Fixed-Fixed 61 3.7.2. Fixed-Pinned 62 3.7.3. Pinned-Fixed 63 3.8. Transformation Matrix 63 3.9. Assemble the Structure Stiffness Matrix 65 3.10. Assemble the Structure Nodal Vector 66 3.11. Solve, Get Nodal Displacements and Forces 66 4. Matrix Formulation and Deformation Based Method 69 4.1. Elastic Method in Distributing Lateral Force 69 4.2. Elastic and Inelastic Method in Distributing Lateral Force 70 5. Shake Table Tests 73 5.1. Introduction 73 5.2. Design of Test Structure 73 5.3. Material Properties 75 5.4. Tests and Observations 75 5.4.1. Tests up to Mul-90% 76 5.4.2. Tests with Mul-120% 76 5.4.3. Tests with Mul-133% 76 5.5. Deformations 77 6. Verification 81 6.1. T Cross Section, Dimensions, Reinforcement and Materials 81 6.2. Moment Curvature Curve 82 6.3. Force Displacement Curve 85 6.4. Force Displacement Curve of the Structure 88 7. Conclusions and Suggestions 91 8. References 93 Appendix 1, Timoshenko Beam 95 • Fixed-Fixed 95 • Fixed-Pinned 95 • Pinned-Fixed 96 Appendix 2, Bernoulli Beam 97 • Fixed-Fixed 97 • Fixed-Pinned 97 • Pinned-Fixed 98

In this thesis, the dynamic structural response of six scaled flexural masonry walls to scaled blast loading is experimentally investigated. These walls have been tested in at an open range with charge masses ranging from 5 kg to 25 kg of Pentex-D explosive material with a TNT equivalency of 1.2, and with a constant stand-off distance of 5 m throughout testing. The field properties of the blast wave, which includes the reflected and free field pressures, were recorded. Additionally, the displacement response histories of the wall over the blast test were recorded and the post-blast damage was documented. This study puts forth several potential models for the analysis of the experimental data. The experimentally obtained blast characteristics were compared to predictions of the Kingery and Bulmash (K-B) model. The strain rates used during the study are equivalent to those developed by a number of studies for the materials used in the construction of the specimens. The results obtained through the experimental program are compared to those from a variety of single degree of freedom models, ranging from simplified linear relationships to complex stress-strain relations accounting for the effects that arise because of the increased strain rate due to blast testing. The simplified model assumes a constant stiffness, mass, and triangular pressure profile to determine the peak deflection of the specimen during an experimental test. The bilinear and nonlinear models are based on the discretization of the wall sections into a number of layers, and using strain-rate dependent, stress-strain relations of the constituent materials to generate stresses within the layers. These stresses then iv form the basis of the resistance function to determine the structural response of the test specimens. In this study, the effect of higher modes of vibration on the test specimens is not included. The bilinear and nonlinear models are then implemented to develop Pressure-Impulse (P-I) diagrams, and the effect of the strain rate on P-I diagrams is investigated. The P-I are then available to be implemented into the recent blast code for reinforced masonry flexural walls. The fitted results of the recorded experimental blast pressure parameters are shown to be adequately approximated by the software ConWep in terms of the peak pressure and specific impulse. Comparing the K-B model, which forms the theoretical basis of ConWep, to the raw pressure profile data obtained from the experimental testing, a significant variations is found in the pressure data while significant scatter is found in the impulse. The analytical results show that increasing the nonlinearity of the material accounts for; the response predicted by the single degree of freedom model more closely relates to the response of the specimens. In addition, strain rate effects have a significant impact on the potential level of protection (LOP) provided by masonry flexural walls, as it has a noticeable effect on the curves of the P-I diagram. / Thesis / Master of Applied Science (MASc)