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While the use of cross-laminated timber (CLT) panels for building construction has increased over the last several decades, current standards and existing literature provide limited information regarding the design of CLT diaphragms or the prediction of their deflections when subjected to wind and strong earthquake motions. This paper presents the design and assessment of a CLT diaphragm that was part of a full-scale two-story structure subjected to shake-table testing. An analytical model is proposed for diaphragm deflection accounting for in-plane shear and bending stiffness, as well as the stiffness of various connections. Moreover, a refined numerical modeling strategy is proposed in order to consider phenomena such as panel-to-panel gap closure. Results indicate that the analytical model yields conservative results both in terms of deflections and forces when compared to the numerical model that simulates similar sources of strength and stiffness. The analytical model is suitable for the design of symmetric diaphragms with regular shapes, whereas the numerical model can also be used to model asymmetric diaphragms with irregular shapes. [ABSTRACT FROM AUTHOR]

A method to calculate structural functionality for building structures based on structural natural frequency was proposed for seismic loading events. Structural functionality loss and recovery were determined by monitoring the change of structural natural frequency during the earthquake events or repair activities. A shape factor was introduced, structural functionality recovery function (SFRF), to consider the repair strategy and repair speed. As an example, this method was applied to obtain the structural functionality curve and seismic resilience of a half scale two-story reinforced concrete (RC) frame structure. This structure was subjected to a series of ground motions on a shake table and then repaired by carbon fiber cloth a total of four times. The results indicate that the SFRF is able to capture the recovery trend of a structure in the repair process. Meanwhile, a damage index-repair target (DI-RT) curve, representing the 5% difference between the proposed and traditional SFRFs, was used to investigate the impact of structural damage degree and repair target. The areas above the curve indicates that the difference between the proposed and traditional SFRFs cannot be ignored. [ABSTRACT FROM AUTHOR]

The understanding of, and ability to predict, the seismic behavior of woodframe structures has improved immensely in the last 10 years. Two notable projects occurred in succession, the Consortium of Universities for Research in Earthquake Engineering (CUREE) and California Institute of Technology (Caltech) CUREE-Caltech Woodframe Project, and the Network for Earthquake Engineering Simulation (NEES) NEESWood Project, which provided greater understanding, improved analytical modeling, and advances in force- and performance-based seismic design (PBSD) of woodframe buildings, respectively. The NEESWood project focused on the development of a PBSD philosophy (and procedures) for midrise woodframe buildings and included full-scale system-level validation. To date, the complete design procedure has not been systematically explained, which serves as the impetus for this paper. While the method was shown to be quite viable, some challenges remain, including identifying a format that would facilitate widespread adoption and use by engineers. Thus, this paper examines the progress, current state, and challenges for PBSD of midrise woodframe buildings. [ABSTRACT FROM AUTHOR]

In the summer of 2009, a full-scale midrise wood-frame building was tested under a series of simulated earthquakes on the world's largest shake table in Miki City, Japan. The objective of this series of tests was to validate a performance-based seismic design approach by qualitatively and quantitatively examining the building's seismic performance in terms of response kinematics and observed damage. This paper presents the results of detailed damage inspections following each test in a series of five shake table tests, and explains their qualitative synthesis to provide design method validation. The seismic test program had two phases. Phase I was the testing of a seven-story mixed-use building with the first story consisting of a steel special moment frame (SMF) and stories 2-7 made of light-frame wood. In Phase II, the SMF was heavily braced such that it effectively became an extension of the shake table and testing was conducted on only stories 2-7, making the building a six-story light-frame multifamily residential building instead of a mixed-use building. All earthquake motions were scalings of the 1994 Northridge earthquake at the Canoga Park recording station with seismic intensities ranging from peak ground accelerations of 0.22 to 0.88 g. The building performed quite well during all earthquakes with damage only to the gypsum wall board (drywall), no sill plate splitting, no nails withdrawing or pulling through the sheathing, no edge tearing of the sheathing, no visible stud splitting around tie-down rods, and reasonable floor accelerations. On the basis of damage inspection, it was concluded that it is possible to design this type of building and keep the damage to a manageable level during major earthquakes by utilizing the new design approach. [ABSTRACT FROM AUTHOR]

• A combination rule of wheel unloading extremes under random earthquake and track irregularity excitations was proposed from a probabilistic perspective view. • The seismic fragility analysis using the incremental dynamic analysis (IDA) was introduced into the vehicle-bridge interaction (VBI) system to simplify the probabilistic derailment assessment. • The accuracy of the IDA-based seismic fragility curve of the derailment was investigated for practical engineering application. With the rapid expansion of high-speed rail networks, the safety of vehicles against derailment on bridges during earthquakes has become a significant concern in bridge design. The vehicle's responses are the combined effect of earthquakes and track irregularities, both random processes. But few studies exist on the combination rule of derailment indexes from the two random excitations. In addition, the seismic fragility analysis commonly used in structural engineering was rarely seen in the derailment analysis. In this paper, the probability density evolution method (PDEM) was used to obtain the probability density function (PDF) of wheel unloading extremes by treating the earthquake and track irregularity as random processes. The combination rule of extremes of wheel unloading ratio from the two excitation sources was investigated by comparing the PDFs of combined results with direct simulation. It is shown that the extreme values of wheel unloading under earthquakes and track irregularities approximately satisfy the SRSS formula. In addition, the seismic fragility analysis using the incremental dynamic analysis (IDA) was introduced into the vehicle-bridge interaction (VBI) system to simplify the probabilistic derailment assessment. By comparing with the fragility curve from the PDEM (it can be seen as an accurate solution), the IDA-based seismic fragility curve estimated by twenty or more earthquake samples was found to have adequate accuracy for engineering application. [ABSTRACT FROM AUTHOR]

Abstract: This paper highlights the development of a rapid visual screening (RVS) tool to quickly identify, inventory, and rank residential buildings that are potentially seismically hazardous, focusing on single-family, wood-frame dwellings with plan irregularity. The SAPWood software was used to perform a series of nonlinear time-history analyses for 480 representative models, covering different combinations of plan shapes, numbers of floors, base-rectangular areas, shape aspect ratio, area percentage cutoffs, window and door openings, and garage doors. The evolutionary parameter hysteresis model was used to represent the load–displacement relationship of structural panel-sheathed shear walls and a 10 parameter CUREE hysteresis model for gypsum wallboard sheathed walls. Ten pairs of ground motion time histories were used and scaled to four levels of spectral acceleration at 0.167, 0.5, 1.0, and 1.5g. An average seismic performance grade for each model was generated based on the predicted maximum shear wall drifts. Five seismic performance grades: 4, 3, 2, 1, and 0, are associated with the 1% immediate occupancy drift limit, 2% life safety limit, 3% collapse prevention limit, 10% drift, and exceeding 10% drift, respectively. The obtained average seismic performance grades were used to develop a new RVS tool that is applicable for checking the seismic performance of either existing or newly designed single-family, wood-frame dwellings. It examines the adequacy of the structure’s exterior shear walls to resist lateral forces resulting from ground motions, including torsional forces induced from plan irregularity. [Copyright &y& Elsevier]