Study On Influence Of Cast-in-situ Slab On RC Frame Structure Achieving "Strong Column Weak Beam"

Investigating and analysing the damage in the earthquake action is a effective method to test and improve the seismic design of buildings. It's found that"strong column weak beam"yield mechanism of reinforced concrete frame structure requested in seismic design requirements didn't appear, but abundant column plastic hinge yield mechanism appeared in the survey on damage from Wenchuan Earthquake. A lot of experts and scholars have conducted a great deal of research, most of the conclusions indicate that cast-in-situ slab is one of the factors which affect the"strong column weak beam"yield mechanism of reinforced concrete frame structure to achieve.Firstly, with and without cast-in-situ slab of the frame structural models were established and designed in accordance with the current codes in this paper. Then in order to study the difference of yield mechanism between the two models, Push-over analytical procedure was used to analyse the models. On the base of this, further study was proceeded to research how the RC frame structure achieving"strong column weak beam"yield mechanism under the influence of cast-in-situ slab. It's found that one of the important parameters is the effective flange width of beam end section. Therefore in order to get the width, a set of contrast models were established and analysed. These contrast models established on the base of the RC frame structure with cast-in-suit slab, and had holes that with different size near the beam end section.According to the research, it's found that under the current codes, 6 times slab's thickness can be taken as the effective flange width of beam end section on each side. The frame beam's bending capacity is enhanced by the steel in the effective flange, so in order to achieve"strong column weak beam", the influence of the steel in the effective flange should be considered when taking pure frame as the model of seismic design.