In Japan, the hybrid rigid bridge which consists of a continuous girders and RC piers,
has recently been widely used due to its low cost and its seismic safety. Especially for
structures where it can use the space below their viaducts can be used such urban highways the application of RC rigid frame piers is effective. And so, a hybrid rigid bridge united with RC rigid frame piers is advantageous for urban highway structures. However, no basic research has been performed and no design code has been established so far for hybrid frame piers that consist of RC rigid frame piers and a few girders bridge. Therefore, we examined the flexural loading capacity of the knee joints penetrating a steel main girder in hybrid frame piers by bending test and the numerical analysis, using L-shaped specimen. We prepared two specimens: a stiffened type with perforated plates and non-stiffened one.
The result shows that the knee joint of hybrid frame piers performs much higher
load-carrying capacity than an ultimate strength calculated by design method of RC rigid
frame. And transfer mechanism between a pier and a cross beam is formed by perforated plates in the knee joint.