Earthquake resistant design of eccentric, braced frame, steel buildings for improved inelastic response

摘要

Using detailed, multi degree of freedom inelastic models, it is shown that eccentric, steel, braced frame type buildings, designed according to Eurocodes 3 and 8, exhibit significant variations in ductility demands among their resisting elements when subjected to strong earthquake motions. More specifically, it is found that elements at the so called "flexible" sides of the buildings exhibit substantially higher ductility demands than elements at the so called "stiff" side. Subsequently, using the same sets of buildings, which we must note are torsionnally stiff, a design modification is implemented and the new designs are again checked for the same earthquake motions. This modification has the effect of reducing the physical eccentricity and as a consequence it reduces substantially the differences in ductility demands between the "flexible" and "stiff" sides of the buildings. The results are quite promising and could be the basis, after more testing, for improving the applicable code.