地铁高架槽形梁足尺模型破坏试验与空间分析研究

通过某城市地铁高架试验段槽形梁桥足尺模型破坏试验,测定结构的极限承载能力,研究其空间受力变形特性及破坏特征。试验结果表明,结构在正常使用和极限状态下的极限荷载分别为设计荷载的1.68和3.0倍,具有足够的安全系数。三维有限元数值计算结果表明,底板存在剪力滞后现象,越接近梁端愈明显。底板纵向剪应力最大值出现在梁端附近截面底板与腹板相交处,支座脱空效应对脱空支座位置的底板应力影响较大,设计中需对梁端进行局部加强处理。跨中截面腹板出现拉应力,最大可达0.91 MPa,设计中应考虑设置一定的竖向抗拉钢筋,防止裂缝产生。

Fracture Load Test and Spatial Analysis for the Full Scale Model of Underground Viaduct Channel Girder

Based on the fracture load test for full scale model of channel girder in an underground viaduct testing segment engineering, the ultimate carrying capacity and the spatial mechanics character of channel girder were studied. Test results show that the ratio of ultimate load of serviceability limit state and of carrying capacity limit state to design load is 1.68 and 3.0 respectively, which means the safe factor is adequate. The 3D finite element mechanics model of the entire girder was also constructed. The values obtained by numerical analysis demonstrated favorable agreement with experimental data. There are shear lags in bottom slab, and the closer to the end of the girder,the greater the shear lag is. The maximum longitudinal shear stress of the bottom slab appears at the interface of slab and web at the end of the girder. Influence of unequalized support is greater near the section of support location, and the end girder should be strengthened in design. Also, there are tension stresses in web at mid-span, and the maximum value reaches 0.91 MPa. Therefore, vertical tension reinforcement should be arranged to ensure the safety of against cracking.