Seismic Behaviour of RC Frame with URM Infill: A Case Study

Abstract

Masonry is one of the most common types of construction materials in India. It is commonly used for infill walls in Ordinary Moment Resisting Frames. The strength based design in the code considers the masonry wall as non-structural element and its load is considered on the corresponding elements. The numerical modeling of infill is completely disregarded during analysis of the structure. To design a building realistically, the behaviour of all the primary components is needed and the load carrying capacities are required to be properly assessed. Apart from the strength based design adopted in the code of practice, the modern and advanced approach to design, the performance based design, needs a proper understanding of the behaviour of all the structural elements. Analytical modeling of infill is attempted by many researchers using equivalent strut and tie models which can idealize the behaviour of masonry infill to some extent. The effect of masonry wall on RC frame can be well understood by continuum modeling. Numerical modeling of masonry infill wall is done using Finite Element Method. This paper attempts to simulate the nonlinear behaviour of URM infill frames with varying storeys using Applied Element Method (ARM). Two bay ordinary moment resisting frame is considered with and without infill and capacity is obtained using Nonlinear Static Pushover analysis. One, two and three storey frames with and without openings are also analyzed to understand the differences in drift ratios and the strength of the frame. It is observed that the bare frame carries lesser drift when compared to the frame with infill. This clearly proves the increase in ductility of the frame when provided with infill. In the analyses of infill frame without door and window openings, the maximum base shear of the frame decreased and the drift carrying capacity increased with the increase in number of storeys. Almost the similar behaviour is observed when the infill frame with openings is analyzed.