装配式空心板桥抗剪加固模型试验

Model Test of Shear Strengthened Prefabricated Voided Slab Bridge

针对传统加固方法受空心板桥作业空间的限制,难以实现空心板桥抗剪加固的这一弊端,提出一种凿除空心板端部顶板并在端部空腔内注入混凝土的空心板桥抗剪加固方法。模型试验结果表明,未加固的空心板在试验荷载作用下,腹板发生开裂后试验构件立即失去承载能力。加固后的空心板在腹板发生开裂后可以继续保持承载,填芯混凝土与空心板混凝土保持整体受力。加固后空心板腹板发生开裂时的荷载较未加固的空心板提高5.1%,极限荷载较未加固的空心板提高19.2%。加固后的加载点的挠度比加固前小21.1%,而加固后跨中截面的挠度比加固前小4.0%。加固后空心板最大剪应变比加固前降低约7%。说明抗剪加固可以有效提高空心板抗剪承载能力,空心板端部填充的混凝土极大地提高了支点附近的局部刚度。

Aiming at the disadvantage that the traditional strengthening method is limited by the working space of the voided slab bridge,which is difficult to strengthen the shear performance of the bridge,a voided slab shear strengthening method that removes the top plate and inject grouting concrete in the end of the slab is proposed.The model test results show that,for the voided slab without strengthening,the slab loses the shear bearing capacity immediately when the web plate cracks emerged under the test load.For the strengthened voided slab,it can remain bearing the load after the web plate cracks,and the grouting concrete and the voided slab maintain suffering as a whole.For the strengthened slab,the load when the web plate cracks emerged is 5.1%higher than the unstrengthened slab,while the ultimate load is 19.2%higher than that of the unstrengthened slab.The deflection of the loading point after strengthening is 21.1%smaller than the unstrengthened one,and the deflection of the mid-span section after strengthening is 4.0%smaller than the unstrengthened one.The maximum shear strain of the slab after strengthening is about 7%lower than the unstrengthened one.The shear strengthening can effectively improve the shear bearing capacity of the slab.The grouting concrete at the end of the slab significantly improves the local stiffness near the end.