体外预应力混凝土简支梁抗剪承载力计算方法

将已进行的13根整体式和14根节段式(胶接缝和干接缝)体外预应力混凝土简支模型梁剪切性能模型试验成果,作为建立抗剪承载力简化计算方法的基础资料。根据模型梁剪切性能试验的研究结果,以施工方法(整体式和节段式)、剪跨比、配箍率、接缝类型、体内外预应力筋配比等为参数建立斜截面抗剪承载力的回归计算公式,基于混凝土双轴强度理论和接缝截面极限平衡条件推导接缝截面抗剪承载力计算公式,利用试验数据对计算公式进行验证。按照我国公路桥梁设计可靠度水平和现行规范的要求对计算公式进行修正,提出可用于体外预应力混凝土梁截面抗剪承载力设计的简化计算方法。研究表明,简化计算方法能有效反映体外预应力混凝土梁剪切破坏特点和各主要因素对抗剪承载力的影响规律。

Calculation method for the shear bearing capacity of simply-supported externally prestressed concrete beams

Test results for the shear behavior of 13 monolithic and 14 segmental(epoxy jointed and dry jointed) simply-supported externally prestressed concrete model beams are employed for formulating a simplified method of calculating the shear bearing capacity.Based on the test results,a regression formula for the oblique section shear bearing capacity is established with the construction type(monolithic or segmental),shear-span ratio,stirrup ratio,joint type,ratio of internal tendons to external tendons,etc.,as the parameters.The shear bearing capacity of joint section is also derived by using the biaxial concrete strength theory and the limit equilibrium condition on joint sections.The two formulas are validated by using the test results.According to the requirements of the current Chinese code and its reliability level for design of highway bridges,a suitable simplified calculation method for the shear bearing capacity in the design of externally prestressed concrete beams is put forward.It is shown that the shear failure behavior and the effects of the main factors on the shear bearing capacity of externally prestressed concrete beams can be represented in the simplified calculation method.