全无缝桥用新型路桥连接板拉伸变形性能试验

Experimental on tensile performance of road-bridge link slab of jointless bridges

为掌握全无缝桥用应变硬化水泥基复合材料(SHCC)路桥连接板的受力性能,特别是在温度荷载作用下的拉伸变形能力,采用等效温变变形模拟温降荷载作用,从理论、试验和数值分析方面开展了温降时SHCC路桥连接板的受力性能研究。首先,建立了SHCC路桥连接板的受力模型,推导了温降时SHCC路桥连接板内力和变形计算公式及公式使用条件。其次,开展了2组不同材料配比的哑铃形SHCC试件拉伸试验,获得了其本构关系;开展了室内SHCC板模型拉伸试验模拟温降荷载作用,测得了SHCC板底滑动摩擦因数,揭示了SHCC路桥连接板的受力机理、裂缝分布规律、吸纳和传递变形的能力。最后,采用三折线本构模型模拟SHCC材料的应力-应变关系,建立了SHCC路桥连接板的有限元模型,分析了其温降时受拉性能。研究结果表明:SHCC试件一的初裂应力为2 MPa,极限应变达4.3%,满足全无缝桥路桥连接板强抗拉变形能力的需求;SHCC板在吸纳纵向变形10 mm时,其表面微裂缝多(约154条),裂缝间距小(2~10 cm),且开裂后裂缝宽度控制在80μm以内,此时张拉端板应力为2.8 MPa,锚固端锚固力为196.6 kN,卸载后裂缝闭合,无纤维被拉出或拉断,验证了SHCC板的强吸纳变形能力,且完全满足全无缝桥变形和受力需求;有限元分析的荷载-位移曲线的变化规律与实测值基本一致,说明该有限元分析采用的SHCC材料三折线本构模型是安全的,可为全无缝的SHCC路桥连接板设计与实施提供理论支撑。

To study the mechanical properties of SHCC(strain hardening cementitious composites)road-bridge link slab for jointless bridge,especially its tensile deformation capacity under temperature load.The equivalent temperature deformation was used to simulate the temperature load,and the tensile performance of SHCC road-bridge link slab under temperature drop were studied by means of theoretical,experimental and numerical analysis.Firstly,the calculation formula of internal force and deformation of SHCC road-bridge link slab under temperature drop was derived and the conditions of using the formula were limited.Secondly,the tensile test of two groups of dumbbells shaped SHCC specimens with different components were test and the constitutive models were derived.The indoor SHCC slab model was carried out,and the sliding friction factor at the bottom of SHCC plate was measured.The stress mechanism,crack distribution law and the ability of absorbing and transferring deformation of SHCC road-bridge link slab were revealed.Finally,the stress-strain relationship of SHCC material was simulated by using trilinear constitutive model,the tensile performance of SHCC road-bridge link slab under temperature drop was established by finite software(ABAQUS),and the tensile performance of SHCC slab under temperature drop was analyzed.The results show that the initial crack stress of SHCC specimen with mix proportion 1 is 2 MPa,and the ultimate strain is 4.3%,which meets the demand of the tensile deformation capacity of the full jointless bridge link slab.When the longitudinal deformation reaches 10 mm,there are nearly 154 micro cracks on the surface of SHCC slab,the crack spacing is small(2 to 10 cm),and the crack width is controlled within 80μm.At the same time,the internal stress of tension end plate is 2.8 MPa,and the anchoring force of anchorage end is 196.6 kN.After unloading,the cracks closed,no fibers is pulled out or broken.This strong deformation absorbing ability of SHCC road-bridge link slab is verified,which fully meets the deformation and stress requirements of full jointless bridge.The load displacement curve of the finite element analysis is basically consistent with the measured value,which proved that the trilinear constitutive model of SHCC material used in numerical model analysis is safe.The theoretical support for the design and implementation of fully jointless SHCC road-bridge link slab are provided by the research results.6 tabs,9 figs,29 refs.