Simulated seismic testing of partially-grouted masonry subassemblages

While most masonry structures constructed in the West Coast of the U.S. are reinforced and fully grouted, almost all reinforced masonry construction in the rest of the country, including regions of high seismic risk, utilizes partial grouting. The popularity of partial grouting is a result of lower material costs, faster rates of construction, and reduced potential for installation problems (e.g. inadequate consolidation of grout). Even though walls are the main lateral load resisting elements in a masonry structure, the seismic performance of partially-grouted reinforced masonry wall systems has not been studied sufficiently and is not understood well given the complexity of their behavior. Recent studies have indicated that current design provisions for partially-grouted masonry walls are not as well developed as those for fully-grouted, reinforced masonry. This paper provides a summary of the test of the first specimen in an ongoing experimental effort to determine the lateral load resistance characteristics of full-size, three-dimensional sub-assemblages representing portions of partially grouted (PG) masonry buildings. The sub-assemblages comprise a shear wall with a window opening, as well as cross walls at either end. The test specimen includes a concrete foundation and a composite roof (i.e. a hollow-core concrete slab with a reinforced concrete topping), and it is loaded by subjecting the roof diaphragm to a quasi-static, cyclic drift history. The test was conducted by researchers from the University of Minnesota at the RTMD Laboratory of Lehigh University that is one of the 14 sites in the NEES (Network for Earthquake Engineering Simulation) program sponsored by the U.S. National Science Foundation (NSF). The specimen is a full-size representation of a portion of a building structure that will be tested at the University of California, San Diego. This paper describes the load-deformation characteristics of the specimens including failure modes, load vs. displacement response, and strength and stiffness deterioration.