earticle

영어

Composite girders can increase the stiffness and strength under the positive bending. It also tends to fracture at the bottom flange, which was observed in 1995 Kobe earthquake. The following problems are enumerated in using such composite girders.
1) Elastic and plastic flexural rigidity of the composite girders differ under the positive and negative bending, which increases the complexity of the frame analysis. 2) The strength estimate of the composite girders under the positive bending is dependent on the effective compressive strength of the concrete slab, so the resistance factor for composite girder is smaller than that for pure structural steel beam. 3) The bottom flange of the composite girder subjects to large strain reversal due to the movement of the neutral axis near to the upper flange under the positive bending, which is thought to be the reason of the bottom flange fracture observed.
This paper showed the elasto-plastic behavior of composite girder. The tests object performed in our country was set as the comparison target of analysis. This analytical method showed comparatively simple agreement with the results of tests on composite girder.