基于荷载试验的预应力简支T梁桥承载能力评估

BEARING CAPACITY EVALUATION OF A PRESTRESSED SIMPLY SUPPORTED T GIRDER BRIDGE BASED ON LOAD TESTING

为综合评估某宽跨比较大的简支梁桥的实际承载能力,确定桥梁的实际运营状况和使用条件,基于荷载试验方法,测试了各静载工况下控制截面的应变、挠度,观察了构件的开裂情况。通过脉动试验、无障碍行车试验、有障碍行车试验研究了该桥的自振特性、不同行车速度下的变形响应及跳车试验下的冲击作用,并将上述测试结果与有限元计算结果进行了对比分析。研究结果表明:在最不利荷载工况下,桥梁梁体实测的应变校验系数为0.80~0.97,挠度校验系数为0.85~1.03,表明该桥强度具有一定的富裕度,而刚度富裕度不足;各工况卸载后,其相对残余变形最大值为10.4%,相对残余应变最大值为10.7%,均未超出JTG/T J21—2011《公路桥梁承载能力检测评定规程》限值20%,表明该桥结构在试验荷载下接近弹性工作状态,无较大的不可恢复变形;当进行行车速度在30 km/h以内的跑车试验时,冲击系数为1.225~1.353,当行车速度为10 km/h时,冲击系数为1.396;实测第1阶竖向频率小于计算理论值,表明该桥梁结构的实际刚度较弱。

In order to comprehensively assess the actual bearing capacity of a simply supported girder bridge with large width-span ratio and determine the actual operation and use condition, the strain, girder deflection and crack of the control section under various static load conditions were tested based on loading test method. Through the pulse test, the barrier-free driving test and the obstacle driving test, the vibration characteristics, the deformation response under different driving speed and the impact action of the bridge under jumping test were also studied, and the above test results were compared with the finite element results. The research results showed that under the most unfavorable load conditions, the measured strain check coefficient of bridge beam body was between 0.80 - 0. 97, and the deflection check coefficient was between 0. 85 - 1.03, which showed abundant strength of the bridge, and the stiffness of the bridge was insufficient. After unloading of various conditions, the maximum value of the relative residual deformation was 10.4% , the maximum value of relative residual strain was 10. 7% , neither exceeding the standard limit of 20% , which showed that the structure of the bridge was close to the elastic working state under the test load without large recoverable deformation. When the driving speed was less than 30 km/h, the impact coefficient was 1. 225 - 1. 353 ,when the vehicle speed was 10 km/h, the impact factor was 1. 396. The measured value of the first order vertical frequency was less than the calculated theoretical value, it was shown that the actual stiffness of the bridge structure was weak.