Seismic evaluation of engineered cementitious composites beam- column-slab subassemblies with various column-to-beam flexural strength ratios

摘要

Previous studies showed that the column-to-beam flexural strength ratio, the effect flange width, and the material nonlinearity were the major factors in determining the failure mechanism of frame structure during seismic loading. For the purpose of evaluating the seismic performance of frame structures, five beam-column-slab subassemblies with various column-to-beam flexural strength ratios were tested, four of which used engineered cementitious composites (ECC) at the joint and plastic hinge regions of the beam, column, and slab (referred to as the expected damaged position below). The findings suggest that the specimens that used ECC material in the expected damaged positions had a greater tendency toward the strong column-weak beam failure mechanism compared with the reinforced concrete specimens, and the use of ECC in the subassemblies enhanced their seismic performance with regard to energy dissipation, ductility, and integrity. The ECC specimen with the expected column-to-beam strength ratio of 1.2 (the ratio in the test was 1.12) still had serious damage at the lower column end. However, the specimen with the expected ratio of 1.6 (the ratio in the test was 1.45) only had multiple cracks at the column ends and did not exhibit obvious damage.