Carol Enyedi*, Mircea Păstrav*:

Effective Flange Width Influence on Seismic Response of RC Frames

* Building Research Institute Cluj-Napoca Branch

According to the Romanian codes of practice, no interaction between the beam and the tensile stressed flanges is taken into account at the Ultimate Limit States. This study was carried out in order to check the influence of the effective flange width of the girders on the seismic behavior of RC frame structures. Analytical analyses revealed that the bending capacity of the beams increases when a larger flange width is taken into account. This fact was confirmed by the tests performed on column -beam joints (with and without slab). The importance of the conclusion is the different response of RC frame structures during strong ground motions then the designed one. So, the “strong column-weak beam” philosophy practically is not developed and it is actually replaced by the “story mechanism”, decreasing the safety factor of structures designed according to the present codes.