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Earthquake-prone regions have seen the resilience of traditional timber-framed masonry construction systems through previous seismic events. The post-earthquake studies show that these building systems have exceptional resilience to seismic activity and can endure multiple seismic events throughout their lifespan. This performance stands out from many contemporary constructions. Although there is a significant amount of evidence regarding the distinct behavior of these structures during earthquakes, there is a limited amount of meaningful quantitative experimental data on their seismic performance. This study showcases the findings of a series of half-scale shake table experiments carried out on a single-room; single-story timber frame filled with dry bond brick masonry. Two half-scale models were created and tested on a shaking table to investigate the seismic performance of timber framed masonry structural systems. One model was left without infill, while the other was infilled with dry bond brick masonry. To analyze the dynamic behavior, both models were exposed to random base excitation. Additionally, the models were tested with gradually increasing ground motion to study their response to seismic activity, following a method known as single ground motion record incremental dynamic analysis. The evaluation focused on the dynamic characteristics, including the assessment of natural frequencies, damping, mode shapes, and stiffness degradation. The stiffness decreased to 43% of the undamaged stiffness in the model with bricks and 62% of the undamaged stiffness in the model without infill. An assessment and evaluation were conducted on the peak acceleration and displacement responses, as well as the global hysteresis response. The acceleration response was significantly higher for the model with brick infill, with an amplification of 300%. In contrast, the model without infill had a lower amplification value of 150%. According to the findings of the study, it is evident that the timber framed structure exhibits a significant level of flexibility and deformability. Additionally, the structure's ability to dissipate energy increased as the peak ground acceleration of the input ground motion increased. [ABSTRACT FROM AUTHOR]

Computer vision enables a much more efficient monitoring system of structural behavior, compared to traditional methods. This derives from the fact that it allows the assessment of displacements in a vast number of points that can be processed to the estimate deformations, accelerations, and other key parameters at relevant cross‐sections. This paper proposes a computer vision‐based methodology, specifically designed for monitoring seismic tests conducted on a shaking table with a reduced‐scale model, using a single camera approach. This innovative methodology uses artificial targets with predefined color and geometry to optimize their detection and tracking. These targets are positioned at key points of the reduced model—“Moving Targets”—and at reference points of the seismic table—“Control Targets.” Videos are recorded during the seismic tests and the coordinates (in pixels) of the targets' centers are automatically detected and captured. Then, transformations are applied to each frame to compute the targets coordinates in millimeters and based on the differences between frames, to calculate the displacements of each target. The methodology was first calibrated with dynamic tests performed on a reduced‐scale model (1:33) of a prefabricated concrete shell, printed in acrylonitrile butadiene styrene (ABS), conducted on an educational shaking table. Afterwards, the methodology was validated with seismic tests performed on a 1:3 reduced model of a prefabricated concrete shell, produced according to the similitude theory to best reproduce the behavior of the corresponding prototype. It was demonstrated the ability of the methodology to monitoring seismic tests, enabling continuous tracking of the targets placed on a structure with complex geometry. [ABSTRACT FROM AUTHOR]

This paper compiles experimental site characterization of an unsaturated tropical soil profile in an experimental research site in Bauru, São Paulo, Brazil. Several in situ campaigns comprised geophysical borehole tests (cross-hole, down-hole and up-hole together with the SPT), as well as mechanical tests (SPT, CPT and SDMT) have been performed. There is an unsaturated sandy soil at the studied site and, according to the MCT Classification System for tropical soils, the first 13 m depth is a colluvium with lateritic soil behavior (LA’) over the residual soil with non-lateritic behavior (NA’). The ratio between seismic (Go) and mechanical (qn, N60, ED, KD and MDMT) parameters was useful to identify the existence of microstructure and to confirm unusual soil behavior for this tropical soil site. CPT and SDMT were efficient for detailed stratigraphic logging, however, the estimative of geotechnical parameters cannot be solely been done base on just conventional correlations defined for sedimentary soil.

The present study deals with the seismic response of three-leaf stone masonry subassemblies before and after the application of intervention techniques. In detail, shaking table tests are performed on a scaled substructure in the Laboratory for Earthquake Engineering, at the National Technical University of Athens (NTUA). The substructure consists of two parallel walls. One wall is of rectangular section, whereas the other is provided with a portion of transverse wall at its mid-length. A flexible timber floor rests on the top of the walls. Sine-sweep and dynamic tests are performed perpendicular to the two walls, before and after interventions. The aim of this work is to experimentally study the response of three leaf masonry walls against in-plane and out-of-plane seismic actions, to investigate the effect of the transverse wall to the out-of-plane behavior of walls (and vice versa) and to assess the effect of a selected set of interventions on the behavior of the substructure. The results of this study confirm the vulnerability of three leaf masonry structures, evidenced by the premature detachment of masonry leaves. They prove the significant role of the transverse wall, in reducing the width of the separation cracks observed in the walls subjected to out-of-plane actions followed by an increase of its in-plane damage, as well as the positive effect (in terms of load and deformation capacity) of grouting the walls and enhancing the diaphragm action of the floor. Additionally, the experimental results of this study can serve as a validation tool for the calibration of numerical models and as input for further analytical research. In this paper, the calibration of a smeared crack model that is based on macro-modeling approach is presented, along with a comparison between experimental and numerical results for the specimen before interventions, based on the performed calibration. • A three-leaf stone masonry substructure is investigated experimentally. • Uniaxial shaking table tests are applied to the specimen before and after interventions. • The inherent vulnerability of the as-built model against earthquake actions is proved. • The strengthened model exhibits a significantly improved seismic response. • Calibration of a smeared crack model, along with the comparison between experimental and numerical results are shown. [ABSTRACT FROM AUTHOR]

An experiment was carried out to investigate the seismic performance of hybrid precast concrete shear walls, which aimed to emulate the monolithic RC wall by incorporating unbonded post-tensioned high-strength strands and vertically connected reinforcing bars by grouting across the horizontal joint for lateral resistance. The unbonded tendons provided the pre-compression and the recentering force. The grouted reinforcing bars were used to provide the bending strength, reduce the gap opening size, and eliminate the horizontal slippage along the joint. Three full-scale emulative hybrid wall specimens under different vertical loads and one monolithic RC wall specimen for reference were subjected to reversed cyclic loading. The test results showed that, the emulative hybrid specimens, with vertical load less than or equal to that of the monolithic specimen, exhibited good lateral performance and the seismic properties, including strength, stiffness, ductility and energy dissipation, were comparable to that of the monolithic specimen. As the vertical load increased, the strength and stiffness were enhanced, however, the energy absorbing capacity was obviously decreased. [ABSTRACT FROM AUTHOR]

Due to the well-known sensitivity of the behaviors of free structures under seismic excitations, the question of the aptitude of a numerical model to accurately represent them arise. To contribute to the answer to this question, this article presents experiments which were carried out on the shaking table of CEA/Saclay in France, on three rigid blocks with geometrical defects, inevitably due to the manufacturing process, subjected to 100 realizations of a random process. These tests were analyzed using specifically-developed indicators, and compared with the results yielded by two numerical models, one with a symmetrical geometry and the other with a non-symmetrical geometry, calibrated to reproduce out-of-plane behavior identified through release tests. Counter-intuitively, this article shows that a numerical model can predict motion over a longer period than an experiment performed on a supposedly identical block. From a statistical point of view, despite experimental uncertainties this article shows a good agreement between numerical and experimental results. Finally, a numerical study, performed using artificial seismic signals, showed that the assumption of perfect geometry can lead to an underestimation of the risk of overturning. Moreover, it is showed that a symmetrical model with a realistic slenderness correction can provide an overestimation of this risk under 1D excitation, but not in 2D. [ABSTRACT FROM AUTHOR]

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Precast concrete frames can sustain earthquakes with little damage, if their beams are not monolithically connected to strong columns but via: (a) unbonded post-tensioned cables, continuous and concentric along all beam spans in the frame, and (b) top and bottom bars which cross the joint unbonded while being well anchored in the beam at both sides of the joint. Such a frame can sway thanks to intermittent opening and closing of the dry interfaces between the beam ends and the columns, instead of plastic hinging and damage at the ends of the beams. A pocket in the foundation typically allows the precast column to sway, without plastic hinging at the base. As this detail is inefficient and increases the vulnerability of the column to blast or impact, it is replaced in the paper with monolithic connection of the column to an isolated footing, which is free to rock and uplift, unrestrained by tie-beams. The lateral load response of such a rocking type frame with two stories and two bays was compared to that of a fixed-base frame. The latter suffered heavy damage at the base of the columns and at weak links along the beam spans, whereas the former confirmed the ability of a dry-jointed rocking frame to significantly reduce structural damage. Certain yielding at the top of the ground-story columns in the rocking frame was due to the artificially low column axial loads, lower than those found in practice even in low-rise buildings. An analysis model appropriately accounting for the flexibility due to the opening of the dry joints and for uplifting (modeled by a pair of no-tension springs under each footing) was found to give good agreement with test results. [ABSTRACT FROM AUTHOR]

A cross-laminated timber (CLT) panel is a heavy timber structural component fabricated by laminating layers of timber boards in an orthogonal pattern. This paper presents a study of the lateral-load response of self-centering (SC) posttensioned CLT structural walls (i.e., SC-CLT walls), which are constructed by posttensioning CLT wall panels to the foundation with vertical posttensioning steel bars. The bars pass through the CLT panels and are anchored to the CLT panels at the top of the wall and to the foundation at the bottom of the wall. Cyclic loading tests were conducted on a series of SC-CLT wall specimens with different configurations. Structural limit states of SC-CLT walls under lateral load are identified. Two types of analytical models are proposed to predict SC-CLT wall response, namely, a design-oriented analytical model based on simple mathematical expressions, and a fiber-element-based numerical model. Comparisons between the analytical and experimental results are made, which indicate that the simple mathematical expressions and the fiber-elementbased numerical model provide accurate estimates of the lateral-load response of SC-CLT walls under cyclic loading. [ABSTRACT FROM AUTHOR]

In the present research a pendular type of seismoisolation system for protection construction from earthquake is considered. Seismic isolation is carried out on the basis of the following principles:• the natural frequency of the "protected object - seismic isolation" should be significantlylower than the main energy contained frequency (which leads to high frequencies filtering);• damping in seismic isolation systems should be high enough to avoid resonance effects;• in seismic isolation systems can be applied elements that limit the level of force that is passed to the protected object (a plastically deformable or friction elements).A design of devices (component of seismoisolation systems) is shown in the article. The methods of seismoisolation systems analysis are described and the results are presented. The main results of dynamic tests of those devices are shown.

The reversed cyclic lateral loading experiments were conducted on three, full scale, emulative hybrid precast concrete shear wall specimens with different post-tensioned forces and one reference monolithic RC shear wall specimen, and the measured results were then discussed in this paper. The emulative hybrid wall combined grouted vertical reinforcements with unbonded post-tensioned high-strength multi-strand tendons for lateral resistance, attempting to emulate the cast-in-place RC wall. Because of the presence of the unbonded post-tensioned tendon, by contrast to the monolithic wall specimen, the emulative hybrid wall specimens possessed higher strength, higher stiffness, and smaller residual displacement. The opening gap, resulted from the discontinuity of concrete and the locally debonding of vertical connecting reinforcements, was limited mainly due to the vertical connecting reinforcements across the joint distributed over total cross-section. Meanwhile, the emulative hybrid wall specimens were capable of providing energy dissipation and ductility capacity comparable to that of the monolithic specimen, and the negative effect of the post-tensioned force on energy dissipation was more obvious than on ductility. Moreover, the post-tensioned tendon remained elastic throughout the test and the yielding of the connecting reinforcements was delayed. [ABSTRACT FROM AUTHOR]

This paper aims at presenting a digital correlation technique to capture the full-field displacement thanks to a high-speed camera of a full scale structure tested on a shaking table. The challenges are both the measurements at a full scale to visualize damages versus the resolution of pictures and the dynamical loading that requires a large number of pictures. The final goal is a better understanding of the seismic behavior of timber-framed structures with infill to help at modeling such structures and predicting their seismic vulnerability. For this purpose, results of shake table tests carried out on a full-scale one-story timber-framed house filled with stones bonded by an earth based mortar are presented and discussed. DIC full-field measurements allow deriving displacements and accelerations on shear walls as well as lateral forces applied on them. The experimental results presented herein allow analyzing the influence of bracing and might be used to propose optimized aseismic constructions based on cheap technological solutions. These results demonstrate the seismic-resistant behavior of timber-framed structures with infill and constitute a key issue for the promotion of such constructions in developing countries. [ABSTRACT FROM AUTHOR]

Concrete encased CFST (CECFST) composite components have prominent advantages over traditional CFST components such as better durability, high stiffness and strength, etc. However, the encased concrete outside caused certain difficulty in connecting to the steel beam. In this paper, two types of bolted assembled joints between CECFST column and steel beam were proposed and tested under cyclic loads, in which the end plate and cover plate joints were included. Typical failure modes of the joints were analyzed and characterized. In comparison, the CECFST column in end plate joints exhibited more severe failure and higher strength than that in cover plate joints. Seismic performance including hysteretic curves and energy dissipation were also discussed. In addition, numerical modelling of the joint was established considering the complicated material models and interactions in the joint core, of which the accuracy was validated against the test results. Further, parametric analyses were performed on the cover plate joints with CECFST columns through the numerical approach. It demonstrated that the axial ratio, thickness and strength of cover plate, diameter of bolt, strength and thickness of steel tube significantly affected the stiffness and strength of the joint. The experimental and numerical results revealed that the proposed two types of joints with CECFST column performed relatively favorable seismic behavior and could be employed in engineering practice. • Two types of novel bolted connections to concrete encased CFST column were proposed and tested under cyclic loading. • Numerical modelling of the joints were developed considering complicated interactions and material models. • The influence of various parameters on the bolted joints were analyzed. [ABSTRACT FROM AUTHOR]

This paper presents the major findings of a shake table testing program on a large-scale (1:2.39) novel segmental concrete singlespan bridge specimen. Emphasis is given on various specimen configurations and seismic loading conditions. The bridge specimen, termed hybrid sliding-rocking bridge, incorporated a box-girder superstructure with rocking joints and internal unbonded posttensioning (PT), and two single-column piers with internal unbonded PT. The pier columns included end rocking joints and intermediate sliding joints along the column height. Various configurations of the bridge specimen were considered with respect to the seismic mass and the superstructureto- substructure connectivity. These configurations were subjected to far-field (F-F) and near-fault (N-F) ground motion ensembles scaled to various seismic hazard intensities. Asynchronous support excitation was also considered. The testing program included approximately 145 seismic tests. The dynamic response of the specimen was found to increase with the seismic hazard intensity and the seismic mass. Near-fault motions resulted in larger deformations in comparison to far-field (F-F) motions, particularly in the vertical direction. Asynchronous support excitation resulted in smaller system deformations compared with in-sync shaking. The system residual deformations, including sliding at the column joints, were small. [ABSTRACT FROM AUTHOR]

This study presents a finite element (FE) model of timber-framed shear walls under seismic loading, which has been validated in Part I under quasi-static loading. In this paper, experimental shake table tests on shear walls are described and some examples of the obtained results are discussed. Then, the refined FE model predictions under dynamic loading are compared to the 11 shake table tests. The final objective of this study is to create a 3D model of timber-framed structures; thus, a simplified FE model is proposed to reproduce the refined FE model predictions at a reasonable computational cost. The calibration method of the simplified model uses the predictions of the refined FE model under quasi-static loading as input. The simplified model is then used for dynamic calculations and its predictions are confronted to the refined FE model ones, in order to validate its behaviour under dynamic loading. Eventually, an efficient method to build the walls of a timber-framed building by coupling simplified FE models is proposed. [ABSTRACT FROM AUTHOR]

A radial-piston hydraulic machine with phase-volume regulation of the supply and amplitude-frequency modulation is considered. This machine is used in the drives of vibrational platforms for the seismic testing of large models and fragments of buildings. It ensures vibrations with amplitude or amplitude-frequency modulation so as to effectively simulate earthquakes. [ABSTRACT FROM AUTHOR]

The experimental and numerical response of crane bridges is studied in this work. To this end, an experimental campaign on a scale model of an overhead crane bridge was carried out on the shaking table of CEA/Saclay in France. A special similarity law has been used which preserves the ratios of seismic forces to friction forces and of seismic forces to gravity forces, without added masses. A numerical model, composed of beam elements, which takes into account non-linear effects, especially impact and friction, and simulates the earthquake response of the crane bridge, is presented. The comparison of experimental and analytical results gives an overall satisfactory agreement. Finally, a simplified model of the crane bridge, with only a few degrees of freedom is proposed. [ABSTRACT FROM AUTHOR]

This paper presents the findings of an experimental study that investigated the response properties of segmental cantilever columns incorporating internal unbonded posttensioning (PT) and slip-dominant (SD) joints. The SD joints exhibited controlled sliding that provided energy dissipation with low damage. All joints of these columns, except for the bottom one, were designed to be SD. The bottom joint was designed to be rocking dominant (RD) and exhibited rocking that offered self-centering to the system. Design objectives and equations are presented. These equations were used for the design of a large-scale cantilever column that was subjected to reverse lateral cyclic loading at its top end, reaching a maximum drift ratio of 14.9%. At small drift ratios (), the response was dominated by sliding of the SD joints that provided energy dissipation (damping). For medium drift ratios (between 3 and 10%), rocking at the bottom joint increased and provided self-centering properties to the system. For large drift ratios (), the self-centering properties decreased, but the damping properties remained practically constant. Rocking at the SD joints remained small at all times. Minor spalling was observed in the SD joints, while concrete crushing was observed at the bottom joint. [ABSTRACT FROM AUTHOR]

This paper discusses the lateral load behavior of two, 0.40-scale, hybrid, precast concrete shear wall test specimens and the behavior of a third precast specimen designed to emulate monolithic cast-in-place RC shear walls. The walls had identical overall geometry and were constructed by placing rectangular precast panels across horizontal joints. The hybrid walls used mild steel bars [Grade 400 (U.S. Grade 60)] and high-strength unbonded posttensioning (PT) strands for lateral resistance, whereas the emulative wall used only mild steel bars. The mild steel bars crossing the base joint were designed to yield and provide energy dissipation, with the PT steel in the hybrid walls reducing the residual displacements of the structure. The mild steel bars at the base of the emulative wall and one of the hybrid walls used Type II mechanical splices, while the other hybrid wall used continuous bars grouted into the foundation. Because of the lack of PT steel, the emulative wall developed a large residual uplift at the base joint, resulting in excessive horizontal slip and strength degradation. The behavior of the hybrid wall with Type II splices was also limited, which occurred because of the pullout of the mild steel bars. In contrast, the hybrid wall with continuous mild steel bars showed superior restoring, energy dissipation, and ductile behavior over larger lateral displacements. The results show the potential for the use of precast walls in seismic regions, while also revealing important detailing considerations. [ABSTRACT FROM AUTHOR]

When designed according to current special moment frame requirements, conventional RC beam-column joints in frame-braced buildings subject to design level seismic loads suffer severe damage. Construction of these conventional beam-column joints is also costly and labor intensive. In this paper, the full-scale experimental behavior of two alternative frame-braced subassemblies incorporating ductile embeds is summarized. Observations from the experiments indicate that both specimens exhibit stable hysteretic behavior with no strength degradation in excess of 7% drift ratio. At design plastic rotations expected of conventional beam-column joints, no joint spalling and only minor damage along beam members was observed. A design-oriented lumped element model is described, which reasonably captures the local behavior of the specimens. [ABSTRACT FROM AUTHOR]

RC core walls are used commonly in modern building construction as the primary lateral load-resisting system. To meet architectural constraints, including elevator, stair, and doorway openings, common configurations include walls coupled together with heavily reinforced, low-aspect-ratio coupling beams. Numerous studies have focused on coupling beams and improved seismic performance and design of coupling beams. However, far fewer research programs have studied the seismic behavior of the coupled wall system. Coupled walls are typically used in mid- to high-rise construction, and understanding their seismic response requires simulation beyond the coupling beam and must include all important yielding components of the system. A research project was undertaken to investigate the response of a midrise coupled wall designed to meet current codes. The advanced testing capabilities of the University of Illinois at Urbana-Champaign George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) experimental facility were used to conduct a large-scale test of a coupled wall. The test specimen modeled the lower 3 stories of a 10-story building. The demands from the upper stories were imposed on each pier using an innovative loading device capable of imposing shear, moment, and axial loads or displacements. Damage progression included yielding of coupling beams, yielding of wall piers, spalling in the wall piers, and the coupling beams. Specimen failure occurred almost without warning at 2.27% drift, resulting in significant loss of lateral and axial load-carrying capacity. The damage sustained included concrete core crushing and longitudinal bar buckling in the compressive wall pier. These experimental results were combined with prior test data to develop improved design models for coupled wall systems. [ABSTRACT FROM AUTHOR]

Although the nonlinear behavior of rocking shallow foundations has been experimentally and numerically demonstrated as an effective tool to dissipate vibrational energy during seismic loading, the engineering community has yet to uniformly accept it as a targeted design mechanism for diffusing seismic energy in a structure. This paper presents results of a centrifuge test program that incorporated inelastic behavior into model building systems via yielding of both structural and foundation components. Three 2-story-1-bay building models were designed with similar layouts but different combinations of foundation and structural component yield strengths and were shaken with a similar suite of earthquake motions. Measurements of behavior of each of the model buildings are presented and cross-compared in terms of time history responses, hysteretic responses of the structural and foundation fuses, and maximum response parameters. A balanced design configuration, wherein the rocking foundation and structural fuse are intended to yield at approximately the same load, is demonstrated to be a well-controlled seismic-resisting system, with greatly reduced seismic ductility demand on the structural components. Moreover, seismic energy is well distributed among the targeted yielding components. In contrast, if the footing is restrained from rocking, the structural component ductility demand is significantly greater than that compared to its demand when the foundation is allowed to rock. In essence, the foundation rocking dominated model demonstrates its ability to protect the superstructure from seismic demands. In contrast, when the rocking foundation capacity is more than twice that of the structural fuse, rotations at the foundations are reduced significantly, at the price of much larger demands to the superstructure. [ABSTRACT FROM AUTHOR]

An experimental study was performed to investigate the earthquake resistance of beam-column connections developed for a precast concrete (PC) moment frame. In the moment frame, PC is used for the columns and U-shaped beam shells, and cast-in-place concrete is used for the beam-column joint and the beam core. Six full-scale cruciform beam-column connections, including a conventional reinforced concrete (RC) connection, were tested under cyclic loading. The test parameters were the reinforcement ratio of the beams and the interface details between the PC column and the PC beam shell. The test results showed that regardless of the test parameters, the RC-emulated beam-column connections exhibited good deformation capacities, which were comparable to that of the conventional RC connection. Because of the diagonal shear cracking and reinforcing bar bond slip at the beam-column joint, however , the stiffness and hysteretic energy dissipation signiicantly decreased. To prevent the degradation of the stiffness and energy dissipation, a strengthening method using headed reinforcing bars was proposed and tested. The performances of the test specimens were evaluated according to the requirements of ACI 374.1-05. On the basis of the test results, design considerations for the beam-column connection were recommended. [ABSTRACT FROM AUTHOR]

Effectiveness of cement kiln dust (CKD) in improving the stiffness of recycled base course materials was studied using both seismic modulus and bench-scale resilient modulus tests. Recycled materials included road surface gravel (RSG) and recycled pavement material (RPM). The modulus of RPM and RSG specimens mixed with CKD increased 5-30 times compared with untreated materials; however, the improvement was not as high as cement stabilization. Modulus generally increased with curing time with more hydration; however, decrease in the modulus of the RPM mixed with 15% CKD during curing is attributed to swelling potential of the CKD. Lower rate of increase in modulus of CKD mixtures compared with cement mixtures with curing time was attributable to the chemical composition of CKD, i.e., high free lime and sulfate contents. Freeze-thaw durability tests resulted in modulus reduction on the order of 0.5 to 0.8 for CKD mixtures and 0.5 for cement mixtures. Attributable to the combined effects of stiffness gain with continuing hydration and stiffness reduction with freeze-thaw cycles, the final modulus of the recycled materials mixed with CKD is 2 to 5 times higher than that of untreated RPM and RSG materials. This study also showed that modulus change of stabilized granular materials can be estimated from seismic Young's modulus. [ABSTRACT FROM AUTHOR]

The behavior of coupled-wall buildings primarily depends on the performance of coupling beams. Existing coupled-wall buildings designed and built prior to the 1970s contain coupling beams reinforced with horizontal and vertical bars. Seismic evaluation of these older buildings is commonly performed using nonlinear static or dynamic analyses techniques. Results from nonlinear analyses depend on the quality of backbone curves that characterize the behavior of the individual coupling beams. Backbone curve construction must, therefore, focus on reliable estimates of the strength and deformation values used to characterize the behavior of the structural component. This paper presents experimental results of four conventionally reinforced coupling beams designed to exhibit different behavior modes during cyclic loading. The effect of different amounts of longitudinal and transverse reinforcement on behavior is highlighted. The measured shear strength of the beams is compared with values calculated using existing equations. The deformation components that contributed to chord rotation are identified and discussed in light of response parameters, such as measured strains and observed cracking. The tests also highlight the importance of accounting for reduction in shear stiffness to accurately determine the deformation response of coupling beams. [ABSTRACT FROM AUTHOR]

The refraction microtremor (ReMi) method uses a linear array of receivers to record passive noise stress waves, thereby negating the need for a strong active source such as those typically employed in other linear-array surface-wave methods. The simplicity of such an approach is very appealing; however, there is a potential for significant uncertainty in shear-wave velocity (Vs) estimates obtained in this manner because much is unknown about the seismic wavefield that is being sampled. This article examines intramethod variability in ReMi dispersion measurements and Vs estimates at shallow bedrock sites. The focus is not on evaluating whether ReMi measurements yielded the 'true' Vs profiles for the study sites, but rather on evaluating how the dispersion curves and Vs profiles at the sites were affected by variations in the seismic wavefield sampled by a linear array of receivers. It was found that changes in the sampled seismic wavefield, obtained through employing various array orientations at a site and inclusion of actively generated noise, resulted in significant variations in the ReMi-obtained dispersion curves and Vs profiles at the study sites, thus yielding a high level of intramethod variability for a given test location. [ABSTRACT FROM AUTHOR]

Abstract: In July 2009, a full-scale mid-rise light-frame wood apartment building was subjected to a series of earthquakes at the world’s largest shake table in Miki, Japan. The test program consisted of two major phases: the building tested in the first phase consisted of a single-story steel special moment frame (SMF) with six stories of wood on top, and the second phase consisted of locking down the steel story and testing the six-story light-frame wood building by itself. This paper focuses on the test results for the seven-story steel–wood building tested to earthquakes having return periods of 72 and 665 years. The objective of this phase of the test program was to investigate the performance of a mid-rise light-frame wood building with a first-story moment frame when subjected to a major earthquake, essentially providing a landmark data set to the seismic engineering research community. The building consisted of 225 square meters for retail space at the first story and 1350 square meters of multi-family residential living space with 23 apartment units above. The building was instrumented with just over 300 sensors and 50 LED optical tracking points to measure the component and global responses, respectively. In this paper the seven-story test specimen is described and the resulting seismic response and behavior is summarized. Detailed damage inspection was performed following each of these tests, and representative images are presented and discussed. The building was found to perform excellently, with very little damage following an event that was slightly larger (×1.16) than the design-level event for the city of Los Angeles, California. The peak global drift at roof level was 166 mm, and the peak inter-story drifts were approximately 1.3%. [Copyright &y& Elsevier]

This paper contains detailed analyses of an experimental study conducted to evaluate the ductility, stiffness degradation and energy dissipation characteristics of rectangular, flanged, and end-confined reinforced masonry (RM) shear walls failing in flexure. The test program consisted of seven two- and three-story RM shear walls, with aspect ratios of 1.5 and 2.2, tested under reversed cyclic lateral displacements simulating seismic loading effects. Documentation of the compressive strains at the wall toes, wall base curvatures, and ductility levels attained are presented. The paper focuses on determining the extent of plasticity over the wall height, evaluating the contribution of flexure and shear deformations to the overall wall lateral displacements, identifying the trend of stiffness degradation, and quantifying the amount of energy dissipation. The rectangular walls displacement predictions at ultimate loads using Canadian Standards Association (CSA) S304.1 were in better agreement with the experimental results compared to the Masonry Standards Joint Committee (MSJC) code predictions. However, both the MSJC code and the CSA S304.1 significantly overestimated the test results for the flanged and end-confined walls. Analysis of the measured displacements showed that the contribution of shear displacement to the overall wall displacement was, on average, 21 and 25% of the total displacement for the walls with aspect ratio of 2.2 and 1.5, respectively. The relationship between the energy dissipation and the ratio of the postyield to the yield displacements was found to be almost linear for the test walls. In addition, the wall stiffnesses degraded rapidly to about 60% of their gross stiffness at very low drift levels (0.1% drift). Measured compressive strain at the wall toes were almost double those specified in both North American codes. Extent of plasticity over the wall height was about 75% of the wall length. The data presented in this paper is expected to facilitate better understanding of RM wall behavior under in-plane load to researchers, practicing engineers, and code developers. This study aimed at presenting the flanged and end-confined categories as cost-effective alternatives to enhance the seismic performance of midrise RM construction in North America. [ABSTRACT FROM AUTHOR]

In July 2009, a full-scale midrise light-frame wood apartment building was subjected to a series of earthquakes at the world's largest shake table in Miki, Japan. This article focuses on the test results of that full-scale six-story light-frame wood building. The objectives of the testing program were to (1) demonstrate that the performance-based seismic design procedure developed as part of the NEESWood project worked on the full-scale building, i.e., validate the design philosophy to the extent one test can and (2) gain a better understanding of how midrise light-frame wood buildings respond, in general, to a major earthquake while providing a landmark data set to the seismic engineering research community. The building consisted of 1,350 m2(14,000 ft2) of living space and had 23 apartment units; approximately one-half one-bedroom units and one-half two-bedroom units. The building was subjected to three earthquakes ranging from seismic intensities corresponding to the 72-year event to the 2,500-year event for Los Angeles. In this paper, the construction of the NEESWood Capstone Building is explained and the resulting seismic response in terms of base shears, selected wall drifts, global interstory drifts, accelerations, hold-down forces, and roof drifts are presented. Detailed damage inspection was performed following each test and those results are summarized also. The building performed excellently with little damage even following the 2,500-year earthquake. The global drift at roof level was approximately 0.25 m and maximum interstory drifts were approximately 2% for the floor average with individual wall drifts reaching just over 3% in one corner of the building at the fifth story. [ABSTRACT FROM AUTHOR]

In this paper, seven reinforced concrete-block shear walls with aspect ratios of 1.5 and 2.2 (two- and three-storey high) were tested under displacement-controlled cyclic loading. The response of rectangular, flanged, and end-confined walls, designed to have the same lateral resistance when subjected to the same axial load, is discussed. In general, high levels of ductility accompanied by relatively small strength degradation were observed in all walls with a significant increase in ductility and displacement capabilities for the flanged and end-confined walls compared to the rectangular ones. For both aspect ratios evaluated, the drift levels at 20% strength degradation were 1.0, 1.5, and 2.2% corresponding to the rectangular, the flanged, and the end-confined walls, respectively. The ductility values of the proposed flanged and end-confined walls were, respectively, 1.5 and 2 times those of their rectangular wall counterparts (with the same overall length and aspect ratio). In addition to the enhanced ductility, a saving of more than 40% in the amount of vertical reinforcement was achieved using the proposed alternative strategies while maintaining the same lateral wall resistance. Existing design clauses were used to predict the wall capacities using the American and the Canadian masonry codes and showed excellent agreement. This will facilitate adoption of the new construction categories with minimal modifications to existing code clauses. The test results indicate that higher ductility than the currently endorsed values by North American codes should be used for rectangular walls. Moreover, higher values should be expected when the proposed strategies are adopted which would significantly reduce the seismic demand on reinforced concrete-block shear wall construction. [ABSTRACT FROM AUTHOR]

The seismic behavior of the proposed precast segmental unbonded posttensioned concrete bridge columns for use in regions of high seismicity was investigated experimentally. Posttensioning tendons were placed in the hollow core of the columns and left unbonded with the surrounding concrete to decrease prestress loss during earthquakes. Bonded mild steel bars continuous across the segment joints, also referred to as energy dissipation (ED) bars, were used to enhance the seismic resistance of the columns. The bars were unbonded at the critical joint to avoid premature low cycle fatigue failure. The objectives of this study were to (1) verify the proposed construction method and seismic detailing for the ED bars and (2) investigate the seismic behavior of the columns with different ED bar ratios and posttensioning forces. Four large-scale specimens were designed and tested with lateral cyclic loading. Test results showed that the proposed construction method and seismic detailing for the ED bars were effective in ensuring the ductility and ED capability of the bars. The specimens exhibited excellent drift capacities that are adequate for use in regions of high seismicity. The hysteretic ED capacity and residual drift of the column increased as the ED bar contribution to the expected column strength λED increased. To maintain self-centering capability, λED of more than 35% is not recommended. [ABSTRACT FROM AUTHOR]

A full-scale, two-story, light-frame wood townhouse building, designed according to modern U.S. engineered seismic design requirements, was tested on two triaxial shake tables operating in unison. The main objective of this experimental study was to determine the dynamic characteristics and the seismic performance of the test building under various base input intensities, representative of both ordinary and near-field ground motions in southern California. The building was tested with and without interior (gypsum wallboard) and exterior (stucco) wall finishes. The test results revealed that the installation of gypsum wallboard to the interior surfaces of structural wood sheathed walls substantially improved the seismic response of the test building. The application of exterior stucco further improved the seismic response of the test building, particularly in its longitudinal direction, where the shear response of low aspect ratio wall piers dominated. These shake table test results provide the evidence of the significant influence that wall finish materials have on the behavior of lateral load-resisting systems in light-frame wood construction. [ABSTRACT FROM AUTHOR]

Double skin composite walls are composed of two steel plate “skins” connected by tie bars, with the space between them filled with concrete. They were developed to reduce wall thickness, to enhance constructability, and to enable rapid construction by eliminating the use of formwork and reinforcing bars. In the present study, cyclic testing was performed to investigate the seismic behavior of isolated and coupled double skin composite walls with rectangular and T-shaped cross sections. The wall specimens failed mainly by tensile fracture of the welded joints at the wall base and coupling beams, or by local buckling of the steel plates. Because of their large depth, the ductility of the wall specimens was not as good as that of beams having less depth. In particular, the ductility of the walls was significantly affected by the strengthening methods used for the wall base. The load-carrying capacities of the isolated and coupled wall specimens were evaluated using plastic stress distributions in their cross sections, which provided satisfactory predictions. [ABSTRACT FROM AUTHOR]

This paper describes a study [ 1 ] on the behaviour and design of drive-in racks with fuses installed to reduce seismically imposed internal actions. Two different cross-aisle framing systems were tested using various earthquake signals and magnitudes. The first system featured cross-aisle frames fully braced from top to bottom using diagonal braces. In the second system, the cross-aisle frames were braced from the top down to the level of the first pallet runner. In the former system, the rack structure was found to be very stiff and hence, it attracted high base shear action causing severe damage to the uprights, braces and connections. The latter system was found to be significantly more flexible, attracting much lower base shears. However, due to the inherent flexibility of the latter system, second order effects due to excessive sway could cause instability especially when spatial plastic hinges develop in the uprights. Based on the outcomes of the study, a new bracing mechanism has been developed to improve the seismic behaviour of steel storage racks using friction-damped seismic fuses. This paper presents the new bracing system with integrated seismic fuses including tests of the components of the fuses. Full-scale tests of complete 3-bay drive-in racks are also presented featuring tests in the elastic range to determine the natural frequencies of the two systems and destructive tests of fully loaded racks subject to common earthquake time histories of increasing magnitude. The paper also discusses the opportunity the seismic fuses present to substantially enhance the seismic performance of steel storage racks. • A seismic fuse concept is presented for steel storage racks to enhance their seismic performance. • The fuse is adjustable to give high in-service stiffness and sliding motion under seismic action. • High levels of damping of up to 15% is achievable by adjustment of the bolt tension. • The fuse is shown to significantly reduce the base shear and hence internal actions. [ABSTRACT FROM AUTHOR]

Abstract: The paper is devoted to stone masonry structures in view of possible improvement of their dynamic-seismic resistance and durability. Many existing structures and large models were investigated by the authors in the framework of national and international research projects. The investigation of a large stone masonry model, tested on the shaking table, had as main purpose the evaluation of the behaviour of new and rehabilitated masonry structures reinforced with polymer grids produced in the European Union. The test plan consisted of the following parts: tests of individual material properties; seismic tests of a masonry model reinforced with polymer grids inserted horizontally in prescribed bed joints; seismic tests of a masonry model reinforced on parts of a wall surface by vertical polymer grids bonded with fibre-reinforced plaster. The paper presents the selected representative results and synthesis of obtained data. The polymer grids and fibre mortars enhance the seismic resistance of stone masonry structures. They contribute also to the durability of historical and other stone masonry structures, especially in cases of vertical polymer grids combined with fibre lime–cement plaster. [Copyright &y& Elsevier]

A quarter-scale, two-span reinforced concrete bridge was tested using the shake-table system at the University of Nevada, Reno. The shake-table tests were part of a multiuniversity, multidisciplinary project utilizing the network for earthquake engineering simulation, with the objective of investigating the effects of soil-foundation-structure interaction on bridges. This paper discusses the development and testing of the bridge model, and selected experimental results, including those that demonstrate the effects of incoherent motions and stiffness irregularities on the distribution of forces and deformations within the bridge system. Motion incoherency affected the asymmetric bridge response (planar torsion of the superstructure), but had little effect on the symmetric bridge response (center-of-mass displacement of the superstructure). These experimental findings are consistent with conclusions from numerical analyses conducted by other researchers. During a 2.0 g PGA earthquake excitation, numerous longitudinal bars buckled and fractured at a drift ratio between 5.5 and 7.9%. Despite the level of damage, detailing of the column transverse reinforcement according to NCHRP 12-49 guidelines provided sufficient column ductility to prevent collapse during a subsequent 1.4 g PGA earthquake excitation. [ABSTRACT FROM AUTHOR]

The most common test to evaluate the representative modulus and nonlinear behavior of base and subgrade materials is the resilient modulus test. Due to the comprehensive nature of the method, the preparation and testing of one specimen may take up to 6 h. For field quality control, a more rapid method of determining the in-place modulus is desirable. One way to achieve this goal is through in situ seismic methods. However, since the seismic tests provide small-strain moduli whereas the resilient modulus tests measure moduli at higher strains, some additional considerations must be taken into account to relate these two moduli. This paper presents some possibilities for relating these tests in a rational manner. [ABSTRACT FROM AUTHOR]