Steel flexural yielding arms can be an effective energy dissipation device for several seismic force resisting systems, including controlled rocking masonry walls. In controlled rocking masonry walls, uplift of the wall from the foundation is allowed in a way that can localize damage and minimize post-earthquake residual drifts. However, along with other modes of failure, sliding of the rocking walls can increase drifts and damage if not adequately addressed. Controlled rocking systems have different alternatives to prevent sliding, which include the use of additional mechanical components (e.g. metal stoppers) at the corners to resist lateral forces while allowing the wall rocking motion. However, these mechanical components hinder the constructability of the wall in some cases. The use of an energy dissipation device (i.e. steel flexural yielding arm) to also prevent the wall sliding mechanism has not been fully explored to date. The development of an easily replaceable energy dissipation device with the ability to simultaneously resist sliding demands is expected to maintain the overall performance of controlled rocking masonry walls, while also enhancing post-earthquake repairability. The objective of the current study is to experimentally investigate the effect of axial forces on the behaviour of steel flexural yielding arms under cyclic loading. In this respect, the study first presents a description of the experimental program, test setup, and instrumentation. Next, the experimental results of the tested specimens are discussed in terms of the effect of axial forces on the load, displacement, and energy dissipation capacities of the tested devices. Finally, new design equations that account for axial forces are proposed and verified against the experimental data along with a finite element model. Based on the results, recommendations are given for the further development of externally attached and replaceable flexural yielding arms for controlled rocking masonry walls. / Thesis / Master of Applied Science (MASc) / Controlled rocking masonry walls can be a cost-efficient alternative to traditional masonry shear walls because of their enhanced performance, specifically to reduce and localize structural damage induced by seismic loads. However, a controlled rocking wall requires additional energy dissipation devices or post-tensioning techniques to compliment the rocking wall to achieve the desired performance. This thesis explores and improves a type of energy dissipation device for controlled rocking masonry walls and aims to provide detailed design specifications for professional engineers. A design and considerations from previous studies are discussed, followed by the experimental validation, and finally new design equations are proposed for this type of reliable, flexural energy dissipation device.

<p>The full-scale base-isolated structure studied in this dissertation is the only base-isolated building in South Island of New Zealand. It sustained hundreds of earthquake ground motions from September 2010 and well into 2012. Several large earthquake responses were recorded in December 2011 by NEES@UCLA and by GeoNet recording station nearby Christchurch Women's Hospital. The primary focus of this dissertation is to advance the state-of-the art of the methods to evaluate performance of seismic-isolated structures and the effects of soil-structure interaction by developing new data processing methodologies to overcome current limitations and by implementing advanced numerical modeling in OpenSees for direct analysis of soil-structure interaction.</p><p>This dissertation presents a novel method for recovering force-displacement relations within the isolators of building structures with unknown nonlinearities from sparse seismic-response measurements of floor accelerations. The method requires only direct matrix calculations (factorizations and multiplications); no iterative trial-and-error methods are required. The method requires a mass matrix, or at least an estimate of the floor masses. A stiffness matrix may be used, but is not necessary. Essentially, the method operates on a matrix of incomplete measurements of floor accelerations. In the special case of complete floor measurements of systems with linear dynamics, real modes, and equal floor masses, the principal components of this matrix are the modal responses. In the more general case of partial measurements and nonlinear dynamics, the method extracts a number of linearly-dependent components from Hankel matrices of measured horizontal response accelerations, assembles these components row-wise and extracts principal components from the singular value decomposition of this large matrix of linearly-dependent components. These principal components are then interpolated between floors in a way that minimizes the curvature energy of the interpolation. This interpolation step can make use of a reduced-order stiffness matrix, a backward difference matrix or a central difference matrix. The measured and interpolated floor acceleration components at all floors are then assembled and multiplied by a mass matrix. The recovered in-service force-displacement relations are then incorporated into the OpenSees soil structure interaction model.</p><p>Numerical simulations of soil-structure interaction involving non-uniform soil behavior are conducted following the development of the complete soil-structure interaction model of Christchurch Women's Hospital in OpenSees. In these 2D OpenSees models, the superstructure is modeled as two-dimensional frames in short span and long span respectively. The lead rubber bearings are modeled as elastomeric bearing (Bouc Wen) elements. The soil underlying the concrete raft foundation is modeled with linear elastic plane strain quadrilateral element. The non-uniformity of the soil profile is incorporated by extraction and interpolation of shear wave velocity profile from the Canterbury Geotechnical Database. The validity of the complete two-dimensional soil-structure interaction OpenSees model for the hospital is checked by comparing the results of peak floor responses and force-displacement relations within the isolation system achieved from OpenSees simulations to the recorded measurements. General explanations and implications, supported by displacement drifts, floor acceleration and displacement responses, force-displacement relations are described to address the effects of soil-structure interaction.</p> / Dissertation

Time history-analyses of building structures have been used for a quite long time for research at universities. Considering the advantage of time-history analysis relative to the equivalent static force method, the National Building of Canada and other modern building codes around the world require the use of time-history analysis in the design of specified types of buildings located in seismic regions. One of the main issues in the use of time-history analysis is related to the selection and scaling of the seismic excitations (i.e., accelerograms) to be compatible with the design spectrum for the location considered. Currently, both recorded (i.e., “real”) accelerograms and artificial accelerograms are used in the analyses. The objective of this study is to determine the effects of the selection and scaling of seismic excitations on the response of reinforced concrete frame buildings. Three reinforced concrete frame buildings with heights of 4 storey, 10 storey and 16 storey, designed for Vancouver (high seismic zone) were used in this study. Five sets of seismic excitations were used in the analysis – one set of “real” accelerograms, and four sets of artificial accelerograms obtained by different methods. All sets were scaled to be compatible with the design spectrum for Vancouver. Both linear and nonlinear time history analyses were conducted on the buildings considered. Interstorey drifts and storey shear forces were used as response parameters. The results from the linear analysis show that both the interstorey drifts and the shear forces are affected significantly by the type of the excitation set. Similarly, the effects of the type of the seismic excitations on the drifts from nonlinear analysis are substantial. On the other hand, the influence of the excitation sets on the storey shears from nonlinear analysis are quite small. Based on the results from this study, sets of scaled real records are preferred for use in time-history analysis of building structures. If such records are not available, then sets of simulated accelerograms based on the regional seismic characteristics should be used.

Time history-analyses of building structures have been used for a quite long time for research at universities. Considering the advantage of time-history analysis relative to the equivalent static force method, the National Building of Canada and other modern building codes around the world require the use of time-history analysis in the design of specified types of buildings located in seismic regions. One of the main issues in the use of time-history analysis is related to the selection and scaling of the seismic excitations (i.e., accelerograms) to be compatible with the design spectrum for the location considered. Currently, both recorded (i.e., “real”) accelerograms and artificial accelerograms are used in the analyses. The objective of this study is to determine the effects of the selection and scaling of seismic excitations on the response of reinforced concrete frame buildings. Three reinforced concrete frame buildings with heights of 4 storey, 10 storey and 16 storey, designed for Vancouver (high seismic zone) were used in this study. Five sets of seismic excitations were used in the analysis – one set of “real” accelerograms, and four sets of artificial accelerograms obtained by different methods. All sets were scaled to be compatible with the design spectrum for Vancouver. Both linear and nonlinear time history analyses were conducted on the buildings considered. Interstorey drifts and storey shear forces were used as response parameters. The results from the linear analysis show that both the interstorey drifts and the shear forces are affected significantly by the type of the excitation set. Similarly, the effects of the type of the seismic excitations on the drifts from nonlinear analysis are substantial. On the other hand, the influence of the excitation sets on the storey shears from nonlinear analysis are quite small. Based on the results from this study, sets of scaled real records are preferred for use in time-history analysis of building structures. If such records are not available, then sets of simulated accelerograms based on the regional seismic characteristics should be used.

An analytical study was performed to evaluate the effect of shear wall ratio on the dynamic behavior of mid-rise reinforced concrete structures. The primary aim of this study is to examine the influence of shear wall area to floor area ratio on the dynamic performance of a building. Besides, the effect of shear wall configuration and area of existing columns on the seismic performance of the buildings were also investigated. For this purpose, twenty four mid-rise building models that have five and eight stories and shear wall ratios ranging between 0.51 and 2.17 percent in both directions were generated. These building models were examined by carrying out nonlinear time-history analyses using PERFORM 3D. The analytical model used in this study was verified by comparing the analytical results with the experimental results of a full-scale seven-story reinforced concrete shear wall building that was tested for U.S.-Japan Cooperative Research Program in 1981. In the analyses, seven different ground motion time histories were used and obtained data was averaged and utilized in the evaluation of the seismic performance. Main parameters affecting the overall performance were taken as roof and interstory drifts, their distribution throughout the structure and the base shear characteristics. The analytical results indicated that at least 1.0 percent shear wall ratio should be provided in the design of mid-rise buildings, in order to control observed drift. In addition / when the shear wall ratio increased beyond 1.5 percent, it was observed that the improvement of the seismic performance is not as significant.

Time history-analyses of building structures have been used for a quite long time for research at universities. Considering the advantage of time-history analysis relative to the equivalent static force method, the National Building of Canada and other modern building codes around the world require the use of time-history analysis in the design of specified types of buildings located in seismic regions. One of the main issues in the use of time-history analysis is related to the selection and scaling of the seismic excitations (i.e., accelerograms) to be compatible with the design spectrum for the location considered. Currently, both recorded (i.e., “real”) accelerograms and artificial accelerograms are used in the analyses. The objective of this study is to determine the effects of the selection and scaling of seismic excitations on the response of reinforced concrete frame buildings. Three reinforced concrete frame buildings with heights of 4 storey, 10 storey and 16 storey, designed for Vancouver (high seismic zone) were used in this study. Five sets of seismic excitations were used in the analysis – one set of “real” accelerograms, and four sets of artificial accelerograms obtained by different methods. All sets were scaled to be compatible with the design spectrum for Vancouver. Both linear and nonlinear time history analyses were conducted on the buildings considered. Interstorey drifts and storey shear forces were used as response parameters. The results from the linear analysis show that both the interstorey drifts and the shear forces are affected significantly by the type of the excitation set. Similarly, the effects of the type of the seismic excitations on the drifts from nonlinear analysis are substantial. On the other hand, the influence of the excitation sets on the storey shears from nonlinear analysis are quite small. Based on the results from this study, sets of scaled real records are preferred for use in time-history analysis of building structures. If such records are not available, then sets of simulated accelerograms based on the regional seismic characteristics should be used.

Time history-analyses of building structures have been used for a quite long time for research at universities. Considering the advantage of time-history analysis relative to the equivalent static force method, the National Building of Canada and other modern building codes around the world require the use of time-history analysis in the design of specified types of buildings located in seismic regions. One of the main issues in the use of time-history analysis is related to the selection and scaling of the seismic excitations (i.e., accelerograms) to be compatible with the design spectrum for the location considered. Currently, both recorded (i.e., “real”) accelerograms and artificial accelerograms are used in the analyses. The objective of this study is to determine the effects of the selection and scaling of seismic excitations on the response of reinforced concrete frame buildings. Three reinforced concrete frame buildings with heights of 4 storey, 10 storey and 16 storey, designed for Vancouver (high seismic zone) were used in this study. Five sets of seismic excitations were used in the analysis – one set of “real” accelerograms, and four sets of artificial accelerograms obtained by different methods. All sets were scaled to be compatible with the design spectrum for Vancouver. Both linear and nonlinear time history analyses were conducted on the buildings considered. Interstorey drifts and storey shear forces were used as response parameters. The results from the linear analysis show that both the interstorey drifts and the shear forces are affected significantly by the type of the excitation set. Similarly, the effects of the type of the seismic excitations on the drifts from nonlinear analysis are substantial. On the other hand, the influence of the excitation sets on the storey shears from nonlinear analysis are quite small. Based on the results from this study, sets of scaled real records are preferred for use in time-history analysis of building structures. If such records are not available, then sets of simulated accelerograms based on the regional seismic characteristics should be used.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Since the last decade there is an important increase of high-rise buildings in Peru, especially in urban areas. Therefore, it is necessary to assess if the Peruvian Seismic Code is applicable for this type of buildings which have long natural periods as their main characteristic. The main objective of this article is to compare the results of the base shear and story drift ratios of Peruvian seismic design code E.030 with those of the ASCE 7-16 standard to the case of high-rise buildings, this due to the fact that there is limited information for tall buildings in Peru or comparison between national or international code for this type of structures. These high rise buildings have square and rectangular plan floors. Half of them have moment frames and reinforce concrete slab around the rigid core and the others have post-tensioned slab as their vertical load resisting system and central core walls with peripheral columns as the lateral force resisting system. Hence, the response spectrum analysis (RSA) is carried out for every case of the four tall buildings with different configurations using both seismic codes. Then results are compared with the linear response history analysis (LRHA) considering five Peruvian ground motions records, which were scaled to 0.45g PGA. It was verified that generally both the base shear and the interstory drifts calculated using ASCE7-16 are less than that obtained with the seismic code E.030.

The large majority of New Zealand's road network is constructed from thin surfaced unbound flexible pavements where a granular layer provides the main structural strength of the pavement. The current New Zealand empirical design theory states that permanent deformation should largely be attributed to the subgrade and that shape loss in the granular layers is simply a consequence of a previously deformed subgrade. However, recent research and field trials have indicated that basecourse shear strains may be a large contributor to rutting in unbound granular layers. The purpose of this investigation was to determine whether the shear strains induced under heavy vehicle loads can be accurately measured using in-situ induction coils and whether the shear strains are related to permanent pavement deformation. In this investigation a rosette configuration of free floating induction coils was designed to measure principal basecourse shear strains. The principal strains were then used to construct Mohr's circle of strain in order to calculate the maximum shear strain occurring in the granular layer. The rosettes were installed in two full scale test pavements at the Canterbury Accelerated Pavement Testing Indoor Facility (CAPTIF). The pavements were loaded with an 8 tonne dual wheel axle load for 1 million and 600,000 load applications respectively and strain and rut depth testing occurred periodically throughout the test life. The research showed that the rosette coil arrangement was a feasible and accurate device for measuring in-situ shear strains in granular pavement layers. Finite element modelling confirmed the accuracy of the system. The results from the two CAPTIF pavements showed that there was a strong linear relationship between the magnitude of the basecourse shear strain and the rut depth at the end of the post construction compaction period. The investigation also showed that shear strain magnitudes in the region of 5000µƐ result in rapid shear failure in the granular layer. In addition, after the post construction compaction period had finished, the rate of change of shear strain was proportional to the rate of change of rut development. The results indicated that there was approximately a 4:1 ratio between the rate of change in rut depth and the rate of change in shear strain after the initial post construction period. Investigations into the effect of load magnitude on the magnitude of the basecourse shear strain showed that a linear relationship existed between the two parameters. Further to this, load location testing revealed that for a dual wheel configuration, 50mm of lateral wheel variation either side of a point of interest was the maximum allowable movement that would result in similar strain measurements. The research highlighted the dominance of the longitudinal tensile strain and shear strain over the vertical compressive strain within granular layers. As a result, these pavement responses should be considered in further granular pavement research in addition to the commonly used vertical compressive strains.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Currently, there is an increase in the demand for tall buildings in the city of Lima. This research proposes to reduce the dynamic amplification factor through the seismic design of tall buildings based on the requirements of Peruvian code considering that they are regular in plan and height. Minimum base shear values according to the comparison of static seismic shear and dynamic shear from the spectral modal analysis were reviewed for cases of buildings larger than 120 m. The study of 28 reinforced concrete buildings was proposed, with different heights - varying from 24 to 36 floors, with different floor configurations, as well as the arrangement of the walls considering as a rigid core structural system. Additionally, the characteristics of the materials, the loads and combinations were defined. The responses of these buildings were determined by the response spectrum analysis (RSA) and then compared with those obtained by the lineal response history analysis (LRHA), for the last analysis, five Peruvian seismic records were used and scaled to 0.45 g. The seismic responses of the LRHA procedure were taken as a benchmark. The result of this study is the analysis and proposal of the C/R factor for high-rise buildings, as well as obtaining the base shear and drift verification. Minimum base shear values can be reduced for high or long-term buildings, being regular in plan and height. / Revisión por pares