Advances in Structural Engineering Research
335896 - Modeling nonlinear behavior of RC floor systems for seismic analysis
Friday, April 20
3:30 PM - 5:00 PM
When subjected to extreme seismic events, beams in reinforced concrete structures experience yielding and cracking. When this occurs, due to the development of flexural cracks and rebar yielding, a beam’s centerline has a tendency to grow by the sum of the crack widths at mid-height. This phenomenon is referred to as “beam growth”. This tendency to grow is restrained by tensile forces in the slab, which in turn cause compressive forces to develop along the axis of the beam. This compressive axial force can considerably affect beam flexural response and thus needs to be adequately accounted for when evaluating the seismic response of a reinforced concrete building. Therefore, it is important to model the tensile resisting force that develops in reinforced concrete slabs. Using a fiber-section nonlinear model of a 7-story reinforced concrete moment frame structure, building seismic response using an aggregated slab element is evaluated under seismic ground motions. The aggregated slab element consists of a truss element to model axial behavior in parallel with a fiber section element (with low axial stiffness) to model flexural response. The truss element will model the transfer of axial load from concrete to steel which occurs upon tensile rupture of the concrete. Nonlinear dynamic analyses are carried out under a suite of ground motions and building response using the aggregated slab element is compared with building response using other floor modelling techniques such as a rigid slab. The impact that different floor modeling techniques have on building response are discussed and conclusions are drawn.