Study on Composite Action between Steel Girder and Lower Concrete Slab in Steel-Concrete Double Composite I-girder Bridge

近年来，以降低造价、缩短工期为目的的钢-混凝土组合桥在日本得到了广泛的应用。例如，在钢箱梁上下表面都有两块混凝土板的钢-混凝土双组合连续箱梁桥就是其中的一个例子。该结构体系的优点是能够减小中间支撑区的钢材下翼缘厚度。目前，箱梁的车间组装成本比双I梁桥的成本更高。为此，笔者提出了钢-混凝土双组合双工字梁桥，但在双组合双工字梁桥中，采用下翼板和腹板同时焊接的头部栓钉的组合作用还不是很清楚。在本研究中，作者对水平方向和垂直方向组合布置的头部螺栓进行了静力和疲劳顶出试验。

Recently, in Japan, the steel-concrete composite bridge aiming at reducing construction cost and shortening work periods is extensively adopted. For instance, the steel-concrete double composite continuous box girder bridge, which has two concrete slabs at upper and lower surfaces of the steel box girder, is one of its examples. The structural system has the advantage of being able to reduce the steel lower flange thickness in the region of the intermediate supports. At the moment, the shop assembly cost of the box girder is more expensive than that of the Twin-I girder bridge. Therefore, the author had been proposed the steel-concrete double composite twin I-girder bridge.However, the composite action by adopting the headed studs welded both on the lower flange plate and web plate in double composite twin-I girder bridges is not yet clarified perfectly. In this research, the author carried out the static and fatigue push-out test for headed stud, which has combination arrangement both in horizontal and vertical directions.