Reinforced masonry construction constitutes about ten percent of all low-rise buildings in the United States. Many of them are commercial, industrial, and school buildings. It is also used for multi-story hotels, college dormitories, and apartments. While most of the reinforced masonry structures constructed in the west coast are fully grouted, almost all reinforced masonry construction in the rest of the country, including regions of high seismic risk, has partial grouting to make it economically competitive. Walls are the main seismic load resisting elements in a masonry structure. The seismic performance of partially grouted reinforced masonry wall systems has not been sufficiently studied and is not well understood due to the complexity of their behavior, which can be attributed to the heterogeneity and anisotropy introduced by masonry blocks, block cavities, mortar joints, and grouted cells. Recent studies have shown that current seismic design provisions for partially-grouted masonry walls are not adequate and likely to be unconservative. However, the seismic safety of these structures also depends on their system-level performance, which is even less understood. This research will advance understanding of the behavior of partially-grouted masonry structures at the system, as well as component, level and develop and validate economically competitive design details and retrofit methods to make new and existing partially-grouted reinforced masonry structures better achieve current seismic performance standards. To this end, seventeen partially-grouted reinforced masonry wall components and subassemblies will be tested with quasi-static cyclic loading, and two full-scale, one-story buildings will be tested with earthquake ground motions on a shake table. An analytical method will be derived to provide more comprehensive assessment of the shear capacities of these walls than available in current codes. Furthermore, advanced computational models will be developed and calibrated with the test data to provide a simulation tool that can be used to better understand the performance of these structures at the global and local levels, and for use in performance-based seismic design. This research is a collaborative effort among the University of California at San Diego, Drexel University, and University of Minnesota. The experimental work will use the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) shake table at the University of California at San Diego, and the hybrid simulation facility at Lehigh University. Data from this project will be archived and made available to the public through the NEES Project Warehouse/data repository (www.nees.org).
Reinforced masonry has many desirable properties as a construction material, such as durability and energy efficiency. Masonry can also contribute significantly to green and sustainable construction with the use of recycled aggregate and high quantity of fly ash in the ingredients. However, the lack of adequate research and well-developed seismic design provisions as compared to other construction materials has led to a steady decline in the use of reinforced masonry. The seismic performance of partially-grouted masonry is of primary importance for many regions in the United States that are susceptible to low-probability but high-consequence seismic events. The research will result in economically competitive design details and retrofit methods to enhance the seismic performance and safety of these structures. The research will provide unique educational experiences and training to graduate and undergraduate students at the three participating universities. The K-12 education component will develop a demonstration module that relates mathematics and sciences to technologies that enhance the safety of the built environment. The project will utilize an advisory panel with members from code development bodies, industry, and professional practice. Research results and recommendations from this project will be communicated to relevant seismic design code committees for timely implementation to lead to safer, earthquake-resilient masonry construction. This award is part of the National Earthquake Hazards Reduction Program (NEHRP).
