【作者】 张国栋；

【导师】 刘红波；

【作者基本信息】 天津大学 ， 土木工程， 2023， 硕士

【摘要】 预应力矩形束合管幕在传统管幕的基础上,通过横向预应力使管节协同受力,从而无需洞内加固和支撑即可满足承载要求。本文以我国首例预应力矩形束合管幕工程为背景,对该结构及其连接节点通过模型试验、数值模拟与理论分析等手段研究了其力学性能及设计方法。主要研究工作和成果如下:（1）预应力矩形束合管幕连接节点抗剪性能的试验研究。进行小尺寸节点模型试验,结果表明,受剪破坏主要发生在结合缝间的锁扣、混凝土及钢-混凝土接触面;承载过程可划分为初裂阶段（0～15%V_u）、带裂缝工作阶段（15～70%V_u）及屈服强化阶段。抗剪因素排序为:预应力钢绞线的数量（62%V_u）>钢绞线的设置（47%V_u）>预应力的设置（39%V_u）>锁扣的设置（9%V_u）>钢绞线的形式（6%V_u）>初始钢-混凝土摩擦力（5%V_u）。配置两根直线型预应力钢绞线的节点相比无钢绞线的承载力提升6倍以上,且延性好。（2）预应力矩形束合管幕连接节点抗剪性能的数值模拟与理论分析。在数值模拟的基础上,提出节点抗剪承载力计算公式及评价方法,揭示各要素对抗剪性能的影响规律并给出工程建议。结果表明,数值模拟和理论结果与试验相吻合;钢绞线布置间距、根数和截面积对抗剪承载力和刚度影响显著,钢绞线预应力、钢管间距和锁扣厚度次之,钢材强度可忽略。建议根据设计荷载确定钢绞线最大允许间距,钢绞线截面积/钢管砼面积控制在11～17×10^-4,钢绞线控制应力靠近0.75倍强度标准值,钢管边长/钢管间距控制在6.7～10。（3）预应力矩形束合管幕连接节点的抗弯性能研究。在数值模拟的基础上,提出节点抗弯承载力计算公式及评价方法,揭示各要素对抗弯性能的影响规律并给出工程建议。结果表明,连接节点的受弯破坏主要表现在结合缝下部张开和上部挤压,属于延性破坏;数值模拟和理论结果相吻合;钢绞线布置间距、根数、截面积和钢管尺寸对抗弯承载力影响显著,钢绞线预应力、钢管间距和混凝土强度影响较小。建议优选较粗钢绞线,管幕跨度/钢管边长及钢管边长/钢管间距均控制在6.7以上,采用C25以上的混凝土。（4）预应力矩形束合管幕结构的力学性能及设计方法研究。对工程管幕进行精细化数值模拟,随后提出束合管幕简化模型与设计计算方法,最终结合工程算例予以分析。结果表明,简化模型的变形规律和内力分布特征与数模结果基本一致,可利用数模结果对理论内力值修正,管幕变形及节点承载满足要求。更多还原

【Abstract】 Based on the traditional pipe roofs,the prestressed rectangular bundled integrate structure can meet the load-bearing requirements without the need for reinforcement and support in the cavity,by making pipes synergistic through lateral pre-stressing.In this paper,the mechanical properties and design methods of the structure and its connections were investigated using model tests,numerical simulations and theoretical analysis in the context of the first case of prestressed rectangular bundled integrate structure in China.The main research work and results are as follows:（1）Experimental study on the shear performance of the connections of the prestressed rectangular bundled integrate structure.Model tests of small size connections were carried out,and the results indicate that the shear damage mainly occurred in the latches,concrete and the steel-concrete contact surfaces between the connections;the bearing process can be divided into the initial cracking stage（0～15%V_u）,the working stage with cracks（15～70%V_u）,and the yield strengthening stage.The shear resistance factors in order of influence are:the number of pre-stressed strands（62%V_u）>the setting of strands（47%V_u）>the setting of prestress in the strands（39%V_u）>the setting of latches（9%V_u）>the form of strands（6%V_u）>the initial steel-concrete friction（5%V_u）.The connections with symmetrical configuration of two straight prestressing strands have more than 6 times higher load capacity and good ductility compared with no strands.（2）Numerical simulation and theoretical analysis of the shear performance of the connections of the prestressed rectangular bundled integrate structure.On the basis of numerical simulations,the calculation formulas and evaluation methods of shear bearing capacity were proposed,further the influence of each element on shear resistance performance was revealed,and the engineering suggestions were given.The results indicate that the numerical simulations and equations are in agreement with the experiments;the arrangement spacing,the number of strand roots and the cross-sectional area have significant effects on the shear bearing capacity and stiffness;the strand prestress,steel pipe spacing and latch thickness are the second;the effect of steel strength can be ignored.It is recommended that the maximum allowable spacing of the strands be determined according to the design loads,the steel strand cross-sectional area/steel pipe concrete longitudinal cross-sectional area is controlled at 11×10^-4～17×10^-4,the strand tension control stress is close to 0.75 times the standard value of ultimate strength,and the steel pipe edge length/steel pipe spacing is controlled at 6.7～10.（3）Study on the flexural performance of the connections of the prestressed rectangular bundled integrate structure.On the basis of numerical simulations,the calculation formulas and evaluation methods of flexural load capacity were proposed,further the influence laws of each element on flexural performance were revealed,and the engineering suggestions were given.The results indicate that the bending damage of the connections is mainly manifested in the opening of the lower part and the extrusion of the upper part,which is ductile damage;the numerical simulations and the formula calculation results are consistent;the arrangement spacing,the number of strand roots and cross-sectional area and steel tube size have significant effects on the flexural bearing capacity;the strand prestress,steel tube spacing and concrete strength have less effects.It is recommended that the project preferably chooses thicker steel strands,the span of pipe roofs/steel pipe edge length and the steel pipe edge length/steel pipe spacing are controlled above 6.7,and the concrete above C25 is used.（4）Study on the mechanical performance of the prestressed rectangular bundled integrate structure.The refined numerical simulation of the engineering pipe roofs was carried out,followed by the simplified models and design methods of the bundled integrate structure.Finally,it was analyzed with the engineering calculation example.The results indicate that deformation law and internal force distribution characteristics of the simplified model are basically consistent with the numerical simulation results,and the numerical model results can be used to correct the theoretical internal force values,meanwhile the load-bearing safety of the connections of pipe roofs meets the requirements.更多还原