Wood-frame shear wall structures are widely used for residential and commercial buildings. These buildings are lightweight, have very ductile connections and includes multiple load paths. The main objective of this dissertation is to evaluate the seismic performance of a wide range of wood-frame shear wall building designs under the influence of modeling and analysis parameter variations. The first step towards the broad objective of seismic performance evaluation is to identify the different modeling and analysis parameters that can have a potential influence in the seismic response variations. The major variations considered in this study include level of critical damping, analytical modeling of damping, hysteresis model shape variations, ground motion characteristics, level of gravity loads, and floor acceleration variations. A subset of building model designs that were originally designed for the development of FEMA P-695 methodology is adapted for the numerical evaluations and a baseline for the variations is established. To study the sensitivity of inherent damping in wood-frame shear wall structures, an extensive literature survey is completed to find the experimentally observed damping levels in these buildings. Later, nonlinear dynamic analysis is performed for the range of damping levels using different Rayleigh damping models. Ground motion scaling methods, source-to-site distance, and peak intensity levels are the selected variations in ground characteristic group. To assist with the ground motion scaling procedures, a computational toolkit is created to produce amplitude and spectrum matched ground motions for response history analysis. The particular hysteresis model CASHEW that is used for the wood-frame shear wall system has a specific load-displacement shape which is a function of the shear wall design. Three key parameters of this model are varied in a range of values that were observed during experimental tests and seismic performance responses are computed for this variations. From the performance evaluations it is observed that the seismic response is quite sensitive to several of the modeling parameter variations and analysis variations mentioned above and has a unique response based on the design of the building. The range of performance variations for the different models are outlined in the chapters included in this dissertation. / Ph. D.

Yes / Construction and demolition waste (CDW) has reached severe environmental and economic dimensions due to its large volume among all solid waste, highlighting the importance of local actions to manage, recycle, and reuse CDW. Ductile demountable connections are necessary to disassemble and reuse the concrete structural members and fast assembly of precast structures in seismic regions without generating waste. In this study, the seismic performance of CDW-based reinforced geopolymer concrete columns has been investigated. Six ½ scaled columns (half of which were demountable and the other half monolithic) were experimentally tested under reversed cyclic lateral displacement excursions, considering three different levels of constant axial loading to determine failure mechanisms, load–displacement responses, ductilities, energy dissipation capacities, stiffness degradation relations, and curvature distributions. The obtained test results were used to determine the performance of CDWbased geopolymer concrete columns and compare the performances of the demountable connection with the monolithic connection. The test results showed that the novel demountable connection for precast concrete frames exhibited better seismic performance in terms of maximum lateral load capacity, initial stiffness, energy dissipation capacity, and maximum curvature than their monolithic counterparts. Besides, increasing the axial compression ratio on the columns caused an increase in lateral load capacity, energy dissipation capacity, energy dissipation ratio, and initial curvature stiffness; however, it decreased the ductility. Finally, the capacity predictions of current codes, i.e., TS500 and ACI318, were conservative when compared with experimental results. / This publication is a part of doctoral dissertation work by the first author in the Academic Program of Civil Engineering, Institute of Science, Hacettepe University. The authors gratefully acknowledge the financial assistance of the European Union’s Horizon 2020 research and innovation program under grant agreement No: 869336, ICEBERG (Innovative Circular Economy Based solutions demonstrating the Efficient recovery of valuable material Resources from the Generation of representative End-of-Life building material). This work was also supported by Newton Prize 2020. The fifth and seventh authors acknowledge the financial support received from the European Union’s Horizon 2020 research and innovation program under the Marie SkłodowskaCurie grant agreement No 894100. / The full-text of this article will be released for public view at the end of the publisher embargo on 4th Oct 2024.

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)

No description available.

Yes / CDW-based concrete requires alkali-activators to generate geopolymerization process. These alkali-activators are difficult to be handled at the construction site and one of the rational ways to built reinforced geopolymer structures is the prefabricated construction. The connection of the precast structures is the most vulnerable component under the effect of seismic actions. Proper detailing and design of connections are crucial for sufficiently-ductile performance under seismic loading. Additionally, to achieve the disassembling and reusing of structural members, a demountable connection, i.e., dry connection, should be used instead of a wet connection. In this study, four novel fully-demountable connections for reinforced construction and demolition waste-based (CDW) geopolymer concrete members are developed. Seismic performances of these different demountable connections and one reference monolithic connections are experimentally investigated. The connections are subjected to reversed cyclic lateral displacements under constant axial loading. Comparisons are made referring to observed damage patterns, connection strengths, moment–curvature relations, initial stiffnesses, plastic hinge lengths, and energy dissipation characteristics of the proposed demountable connections and the monolithic connection. The results of the experimental study indicate that one proposed demountable connection exhibited larger lateral capacity and better seismic performance than its monolithic counterpart, whereas the other three proposals showed less performance than the monolithic counterpart. / The authors gratefully acknowledge the financial assistance of the European Union’s Horizon 2020 research and innovation programme under grant agreement No: 869336, ICEBERG

Yes / A novel prestressed precast reinforced concrete (RC) beam-column joint, composed of prestressed tendons, stiffened steel sleeves, and high-strength bolts, having improved self-centring ability and assembly efficiency is proposed in this paper. Four prestressed precast RC joints assembled by steel sleeves and one cast-in-place RC joint were tested under cyclic loading to investigate the seismic response of the proposed joint. The main parameters studied are the axial compression ratio of columns, stirrup ratio in the core area of the proposed joint and effective prestress of tendons. The energy dissipation capacity, bearing capacity, and self-centring ability of the prestressed precast RC beam-column joints assembled by steel sleeves are higher than those measured for the cast-in-place RC joint. For the prestressed precast RC joints assembled by steel sleeves, both yield and ultimate displacements increase with the increase of the axial compression ratio, stirrup ratio and effective prestress, but the ductility decreases with the increase of the axial compression ratio and effective prestress. The increasing of axial compression ratio can lead to an increase in the energy dissipation capacity, shear capacity and residual displacement. Finally, formulae to predict the shear capacity of prestressed precast RC joint assembled by steel sleeves are proposed, being in good agreement with the experimental results. / The authors would like to thank the financial support provided by the Natural Science Foundation of Jiangsu Province, China (BK20201436), the Open Foundation of Jiangsu Province Engineering Research Center of Prefabricated Building and Intelligent Construction (2021), the Blue Project Youth Academic Leader of Colleges and Universities in Jiangsu Province (2020) and the Postgraduate Research & Practice Innovation Program of Jiangsu Province, China (KYCX21_3225).

This research introduces and develops a counter-intuitive seismic retrofit strategy, referred to as “Selective Weakening” (SW), for pre-1970s reinforced concrete (RC) frames with a particular emphasis on the upgrading of exterior beam-column joints. By focusing on increasing the displacement and ductility capacities of the beam-column joints, simple retrofit interventions such as selective weakening of the beam and external post-tensioning of the joint can change the local inelastic mechanism and result in improved global lateral and energy dissipation capacities. The thesis first presents an extensive review of the seismic vulnerability and assessment of pre-1970s RC frames. Following a review of the concepts of performance-based seismic retrofit and existing seismic retrofit solutions, a thorough conceptual development of the SW retrofit strategy and techniques is presented. A “local-to-global” design procedure for the design of SW retrofit is proposed. Based on the evaluation of the hierarchy of strength at a subassembly level, a capacity-design retrofit outcome can be achieved using various combinations of levels of beam-weakening and joint post-tensioning. Analytical tools for the assessment and design of the SW-retrofitted beam-column joints are developed and compared with the test results. Nine 2/3-scaled exterior joint subassemblies were tested under quasi-static cyclic loading to demonstrate the feasibility and effectiveness of SW retrofit for non-ductile unreinforced beam-column connections. Parameters considered in the tests included the presence of column lap-splice, slab and transverse beams, levels of post-tensioning forces and location of beam weakening. Extensive instrumentation and a rigorous testing regime allowed for a detailed experimental insight into the seismic behaviour of these as-built and retrofitted joints. Experimental-analytical comparisons highlighted some limitations of existing seismic assessment procedures and helped in developing and validating the SW retrofit design expressions. Interesting insights into the bond behaviour of the plain-round bars, joint shear cracking and post-tensioned joints were made based on the experimental results. To complement the experimental investigation, refined fracture-mechanic finite-element (FE) modelling of the beam-column joint subassemblies and non-linear dynamic time-history analyses of RC frames were carried out. Both the experimental and numerical results have shown the potential of SW retrofit to be a simple and structurally efficient structural rehabilitation strategy for non-ductile RC frames.

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.

An analytical study is performed to evaluate the influence of shear wall area to floor area ratio on the behavior of existing mid-rise reinforced concrete buildings under earthquake loading. The seismic performance of five existing school buildings with shear wall ratios between 0.00% and 2.50% in both longitudinal and transverse directions and their strengthened counterparts are evaluated. Based on the structural properties of the existing buildings, additional buildings with varying shear wall ratios are designed. Consequently, twenty four buildings with different floor plans, number of stories, cross-sectional properties of the members and material strengths are acquired. Nonlinear time-history analyses are performed for all buildings by utilizing the software program, SAP2000 v14.2.0. under seven different ground motion records. The results indicated that roof drifts and plastic deformations reduce with increasing shear wall ratios, but the rate of decrease is lower for higher shear wall ratios. Buildings with 1.00% shear wall ratio have significantly lower roof drifts and plastic deformations when compared to buildings with 0.00% or 0.50% shear wall ratio. Roof drifts and plastic deformations are minimized when the shear wall ratio is increased to 1.50%. After this limit, addition of shear walls has only a slight effect on the seismic performance of the analyzed buildings.

Current seismic design approach of bridge structures can be categorized into two distinctive methods: (i) force based and (ii) performance based. AASHTO LRFD seismic design specification is a typical example of force based design approach especially used in Turkey. Three different importance categories are presented as &ldquo / Critical Bridges&rdquo / , &ldquo / Essential Bridges&rdquo / and &ldquo / Other Bridges&rdquo / in AASHTO LRFD. These classifications are mainly based on the serviceability requirement of bridges after a design earthquake. The bridge&rsquo / s overall performance during a given seismic event cannot be clearly described. Serviceability requirements specified for a given importance category are assumed to be assured by using different response modification factors. Although response modification factor is directly related with strength provided to resisting column, it might be correlated with selected performance levels including different engineering response measures. Within the scope of this study, 27216 single circular bridge column bent models designed according to AASHTO LRFD and having varying column aspect ratio, column diameter, axial load ratio, response modification factor and elastic design spectrum data are investigated through a series of analyses such as response spectrum analysis and push-over analysis. Three performance levels such as &ldquo / Fully Functional&rdquo / , &ldquo / Operational&rdquo / and &ldquo / Delayed Operational&rdquo / are defined in which their criteria are selected in terms of column drift measure corresponding to several damage states obtained from column tests. Using the results of analyses, performance categorization of single bridge column bents is conducted. Seismic responses of investigated cases are identified with several measures such as capacity over inelastic demand displacement and response modification factor.