梁式桥利用实测挠度值推算应力大小方法探讨

Method of Strain Calculation by Deflection Value of Beam Bridge

当前T梁、空心板以及等截面连续梁桥等的结构荷载试验比比皆是,要正确评定此类结构的承载能力,试验现场受条件的限制,准确测试梁的应变是困扰广大检测工程技术人员的难题.利用实测梁的变形来推算梁的应力方法可行,从理论上推导了简支梁、两端固结梁、两端固结梁、三跨连续梁分别在集中力、均布力的作用下的变形与应变关系式.利用某三跨等截面连续梁进行试验验证,第二跨实测与计算值应力与变形比分别为0.018 309、0.018 669,两者相差1.93%,第一跨、第三跨跨中应变和挠度比在0.018 750-0.019 607之间,与第二跨跨中的应变挠度比较为接近.推导变形与应变关系式可为T梁、空心板结构荷载试验的应变(动挠度)测量提供参考.

At present the T-bean and cored slab are widely used as the test everywhere. It is correctly to evaluate the bearing capacity of this kind structure that is limited by the trial site. It is a big problem for technicians to test the strain of it. It is practical to calculate the strain by use of deformation of practical measure beam. In theoretically this paper discusses the relations between deflection and strain of simply-supported beam, clamped-clamped beam and the clamped-reamed beam. Secondly the ration scale between the calculation strain value and deformation is 0.018 309, 0.018 669. the gap value is 1.93%. The change and deflection is between 0.018 750-0.019 607 the first cross and the third cross that is near to the change of the second cross. It is deducted to the change and the applied relation form can be used as the Tbeam. The hollow slab structure load test is for reference only.