横隔板开裂条件下装配式T梁桥的面外形变效应

Out-plane Deformation Effects of T-shape Beam Bridge with Cracked Diaphragms

为探讨汽车偏心加载条件下装配式预应力混凝土简支T梁桥横隔板开裂对腹板面外形变效应的影响,以交通部2008年桥梁通用图中30 m混凝土T梁为工程背景,利用实体有限元模型对比分析了裂缝长度改变情况下腹板最大拉应力、腹板两侧最大绝对应力差、T梁横向变形和中性轴最大应力。通过分析发现:汽车荷载作用下装配式混凝土T梁桥腹板在发生面内竖向弯曲的同时,还存在着面外横向弯曲变形,T梁腹板面外横向变形会产生横向弯矩、减小T梁受压区高度,远离偏载一侧的T梁面外形变效应更为显著;横隔板的开裂会在一定程度生同时增大T梁面内、面外变形和腹板拉应力幅值,但当裂缝长度超过30 cm后梁体面外变形效应变化不再明显。

In order to investigate the out-plane deformation effects of T-shape beam bridge with diaphragm cracking under eccentric vehicles, a simple supported beam bridge with 30 m span length in the bridge general drawing of the ministry of transportation in 2008 was analyzed by ANSYS with solid-element model. The maximum out-plane deformation, tension stresses and the stress at neutral axis were obtained and compared with different crack lengths in the middle diaphragm. The results show that the webs of T-shape girder may not only bend in plane but also bend out of plane, and the out-plane effect of girders apart from vehicle loads may be more significant. The out-plane deformation of girders may reduce the depth of compression and cause horizontal bending moments. Moreover, the out-plane effect, such as horizontal deformation and stress may increase in some extent when the middle diaphragm cracks, but this effect may become unapparent once the crack length exceeds 30 cm.