Published on January 16, 2018
As part of a project aiming to obtain necessary experimental data for understanding the behavior of reinforced masonry walls, project PI Benson Shing and his team will be conducting shake table tests at the UC San Diego experimental facility, starting in April 2018. There are excellent opportunities for payload experiments, and Shing encourages NHERI researchers to consider taking advantage of this large-scale test.
Seismic design codes have to ensure that buildings have a low probability of collapse in the event of a severe earthquake. To develop such standards, the ability to assess the collapse margin ratios of building systems designed according to given specifications is of critical importance. Under severe seismic forces, reinforced masonry (RM) wall structures might develop complicated nonlinear behavior involving interaction between steel and masonry. Furthermore, the interaction of structural walls with other elements in a building system could lead to nonlinear behavior and collapse mechanisms that were not anticipated in design, including behavior dominated by diagonal shear cracks. The ability of analytical models to capture these mechanisms and interactions is essential to have an accurate assessment of the collapse margin ratio of a building. The main aim of this project is to obtain necessary experimental data to understand the behavior of RM wall structures to the point of collapse, and to use the data to advance and validate refined as well as simplified analytical modeling methods.
In this project, experimental and numerical studies will be carried out to quantify: (1) the influence of wall flanges on the shear strength and ductility of RM walls; (2) the influence of the coupling forces introduced by horizontal diaphragms in a building on the strength and deformation capability of the structural system; and (3) the influence of non-seismic load carrying walls and columns on the drift capacity and collapse resistance.
For the experimental study, two full-scale RM wall systems have been scheduled to be tested to collapse on the outdoor shake table at the UC San Diego NHERI site. They are identified as Specimens 4 and 5 in the research proposal. As shown in Figures 1 and 2, these wall systems have different levels of complexity to examine the influence of walls perpendicular to the direction of the seismic forces on the performance and collapse resistance of a wall system. Both specimens are one-story tall. Each specimen will be subjected to a sequence of earthquake ground motion records of increasing intensities till collapse. During a test, cracks developed in the walls will be marked and recorded, the deformation of the walls and reinforcing bars will be monitored with displacement transducers and strain gauges, and the accelerations of the specimen at the roof and base levels will be measured with accelerometers. After each test with an earthquake ground motion, the specimen will be subjected to white-noise excitation to identify any change in the natural frequencies of the structure.
The tests are scheduled to be carried out in the time period between April and October 2018. The test schedules for the two specimens are shown in Figures 3 and 4.
The shake-table tests provide payload research opportunities, which could be supported by the NSF. Examples of possible payload projects include the deployment and validation of innovative sensing and measuring technologies as well as system identification techniques for damage assessment. Interested researchers may contact Dr. Benson Shing, the project PI, at firstname.lastname@example.org for any information needed for their payload project planning and proposals to the NSF
Collapse Simulation of Shear-Dominated Reinforced Masonry Wall Systems
P. Benson Shing, PI
Department of Structural Engineering
University of California, San Diego