斜坡型大纵坡T梁球型支座破坏原因分析和处治

Analysis and Treatment for Spherical Bearing Damage of T-beam with Large Longitudinal Slope

对于山区斜坡型大纵坡桥梁,通常采用T梁和球型支座以适应结构复杂的转动和形变需求。然而,在施工质量和服役环境等多种因素影响下,支座常出现位移超限和脱空等病害,严重威胁了桥梁的安全运营。采用现场试验方法,以球型支座位移、支座梁底预埋钢板水平度、伸缩缝宽度、主梁梁端间距和桥墩垂直度为评价指标,剖析了支座病害的成因。以某山区一座跨径为4×30 m+(65+110+65)m的桥梁为例,分析了该桥T梁球型支座的破坏情况,提出了处治措施,并得到以下结论:T梁架设时支座临时约束解除后未消除的支座初始位移、桥墩抗弯刚度偏小、梁底预埋钢板水平度超限(水平度达到-1.72°(负号表示下坡)以上),是导致球型支座出现位移超限和脱空等问题的主要原因,可采用自调平支座和盖梁顶增设纵向限位装置等措施来解决支座破坏问题。

For bridges with large longitudinal slopes in mountainous areas,T-beams and spherical bearings are often used to accommodate the complex rotation and deformation of the structure.However,under the influence of various factors of construction quality and service environment,the bearings often suffer from displacements exceeding the limits and dislocations,which seriously threaten the safe operation of the bridge.Under the evaluation indicator of the spherical bearing displacement,the level of the pre-buried steel plate at the base of the bearing,the width of the expansion joint,the spacing between the beam ends of the main girders and the vertical straightness of the bridge piers,the causes of bearing defects were analyzed by field test methods.Taking a large span bridge with a span of 4×30 m+(65+110+65)m in a mountainous area as an example,the damage of the T-beam spherical bearing of the bridge was analyzed.The following measures were proposed and concluded that the initial displacement of the bearing which was not eliminated after the temporary restraint of the bearing was released during the erection of the T-beam,the small bending stiffness of the bridge pier and the excessive level of the pre-buried stel plate at the bottom of the beam(the level reached-1.72°(negative sign)are the main reasons for the displacement overrun and the dislocation of the spherical bearing.That self-leveling bearing and additional longitudinal limiting device at the top of the cover beam can solve the bearing damage.