先张法PC空心板剪压区裂缝分析及计算

Analysis and Calculation of Cracks in Shear-Compression Zone of Pre-tensioned Voided PC Slabs

为得到先张法PC空心板剪压区裂缝的发展规律及斜裂缝宽度的计算方法,通过16mPC空心板在不同剪跨比下的抗剪试验,记录各剪跨比下结构剪压区裂缝的参数,与钢筋混凝土剪压区裂缝宽度对比分析,总结了先张法PC空心板剪压区裂缝的发展阶段以及裂缝宽度的变化规律。在剪力作用下剪压区裂缝随剪跨比的增加斜裂缝投影长度增大,斜裂缝倾角变小。以箍筋应力作为计算剪压区裂缝宽度的主要参数,通过试验数据的回归,得到在箍筋极限抗拉强度内先张法PC空心板剪压区裂缝的计算公式,并采用同批次板抗剪试验及天津大学13mPC空心板的试验数据进行验证,结果表明建立的计算公式正确。

To examine the propagation of cracks in the shear-compression zone in the pre-tensioned voided PC slab and the calculation methods for the width of the oblique cracks, the anti-shear tests for the 16 m-long voided PC slabs under different shear-span ratio were done, to record the parameters of cracks in the shear-compression zone under different shear-span ratios.The widths of the cracks in the shear-compression zone were compared with those in the shear-compression zone of reinforced concrete, to gain the propagation stage of the cracks in the shear-compression zone of pre-tensioned voided PC slabs and the variation rule of the crack width.Under the shear forces, the projection lengths of the oblique cracks extend and the inclining angles of the oblique cracks become smaller as the increase of the shear-span ratio.By taking the stresses of the stirrups as the main parameters in calculating the widths of the cracks in the shear-compression zone, the calculation formula for the cracks in the shear-compression zone of pre-tensioned voided PC slabs within the limit tensile strength of the stirrups were gained via the reversion of the testing data.And the results were verified by the anti-shearing tests of the slabs in the same batch and the testing data of 13 m-long voided PC slabs by the Tianjin University.The results indicate that the calculation formula established is correct.