THE SEISMIC BEHAVIOR OF INFILLED LIGHTLY REINFORCED -• CONCRETE STRUCTURES

Abstract

Urueinforced masonry infill walls have significant influence on the seismic performance of a lightly reinforced concrete frames (LRCF). LRCF could be defined as structures designed without consideration of lateral forces due to earthquakes or wind. In this research the interaction between masonrv infill walls and LRCF under seismic excitation is investigated. A two story, two bay by one bay, 1/4 scale lightly reinforced concrete infilled structure is used in this research. The infill is an unreinforced masonry concrete blocks not connected to the building frame. A single degree of freedom earthquake simulator "shaking table" is used to apply earthquake loading to the structure under consideration. An enhanced off-line compensation technique for shaking table calibration is achieved in order to minimize the expected distortion of the shaking table output. The model sttucrure was subjected to a series of tests to evaluate its performance before, during and after earthquake. Three rypes of tests were conducted to detennine the dynamic properties and to study the general behavior of the test structure. The first two tests which are free vibration and static load tests were carried out before and after each seismic rest to evaluate the change in structural properties from the seismic test. The third test consisted of applying the rime scaled Taft S69E 1952 earthquake component to the model structure at different amplitudes until significant damage was observed.