【作者】 杨顺；

【导师】 田水； 李泰来；

【作者基本信息】 武汉理工大学 ， 土木工程（专业学位）， 2024， 硕士

【摘要】 2020年,中国宣布了碳达峰、碳中和的目标愿景。在常规的基坑工程中,临时的支护结构在主体结构施工完成后就被拆除或者遗弃在地下,造成极大的资源浪费。为了响应国家“双碳政策”,实现节能减排,国内许多基坑工程采用永临结合的设计和施工方法,将临时的钢格构柱与永久的结构柱一体化设计与施工。然而对于永临结合的地下框架结构柱两阶段受力性能还有待进一步了解。本文通过理论分析和数值模拟,结合具体工程案例,对永临结合的地下框架结构柱两阶段受力性能展开研究,为永临结合的地下框架结构柱在实际工程中的应用提供理论支撑。本文主要工作内容和结论如下:(1)研究了永临结合的地下框架结构柱在临时支护阶段的受力性能。选用三弹簧模型来考虑桩土效应的影响,建立了带水平支撑的柱计算模型,推导出考虑柱剪切变形影响的带水平支撑的柱屈曲临界荷载和计算长度系数计算公式,公式计算结果与有限元分析结果吻合较好。探讨了桩径、地基土比例系数和水平支撑抗弯刚度对带水平支撑的柱稳定性的影响。(2)研究了永临结合的地下框架结构柱在永久使用阶段的受力性能。分析了偏心荷载作用下格构式型钢混凝土柱中箍筋和钢构架对混凝土的约束机理。采用纤维模型法建立了二次受力格构式型钢混凝土偏压柱的数值分析模型,模型采用了考虑应变梯度影响的约束混凝土本构模型,并对纤维模型法进行了算法优化,数值分析结果与试验结果基本吻合。在此基础上进行参数分析,探讨了初应力系数、角钢屈服强度、混凝土强度、截面含钢率、偏心距和长细比对二次受力格构式型钢混凝土偏压柱力学性能的影响。(3)将受压区混凝土应力图和角钢应力图等效为矩形应力图,基于叠加理论和极限平衡理论,建立了一次受力格构式型钢混凝土偏压柱正截面承载力计算公式,公式计算结果与试验结果吻合较好。分析了我国5本规范中二次受力外包混凝土构件的计算方法,在一次受力格构式型钢混凝土偏压柱正截面承载力计算公式的基础上,通过数据拟合建立了二次受力格构式型钢混凝土偏压柱正截面承载力计算公式,公式计算结果与数值分析结果吻合较好。更多还原

【Abstract】 In 2020,China announced its goal of reaching carbon peak and carbon neutrality.In conventional foundation pit projects,temporary support structures are removed or abandoned underground after the construction of the main structure is completed,resulting in a great waste of resources.In order to respond to the national"double carbon policy"and realize the energy saving and emission reduction,many pit projects in China have adopted the design and construction method of permanent temporary combination,which integrates the temporary steel lattice columns with the permanent structural columns.However,it remains to be further understood the two-stage force performance of underground frame structure columns with permanent temporary combination.In this paper,through theoretical analysis and numerical simulation,the two-stage force performance of underground frame structure columns with permanent temporary combination is studied,so as to provide theoretical support for the application of underground frame structure columns with permanent temporary combination in actual projects.The main work and conclusions of this paper are as follows:(1)The force performance of underground frame structure columns with permanent temporary combination in the temporary support stage is studied.The three-spring model is used to consider the influence of pile-soil effect,and the calculation model of column with horizontal support is established,and the formula for calculating the buckling critical load and calculation length coefficient of column with horizontal support considering the influence of the shear deformation of the column is deduced,and the calculation results of the formula are in good agreement with the results of finite element analysis.The effects of pile diameter,foundation soil scale factor and bending stiffness of horizontal support on the stability of column with horizontal support are discussed.(2)The force performance of the underground frame structure columns with permanent temporary combination in the permanent use stage is studied.The constraint mechanism of stirrup and steel frame on concrete in lattice steel reinforced concrete columns under eccentric loading is analyzed.The numerical analysis model of the secondary stressed lattice steel reinforced concrete eccentric columns is established by using the fiber model method,the model adopt the constitutive model of confined concrete considering the influence of strain gradient,and the algorithm optimization of the fiber model method is carried out,the numerical analysis results are basically in line with the test results.On this basis,parametric analysis was carried out to investigate the effects of initial stress coefficient,yield strength of angle,concrete strength,steel content of cross-section,eccentricity and slenderness ratio on the mechanical properties of secondary stressed lattice steel reinforced concrete eccentric columns.(3)The concrete stress diagram in the compression zone and the angle stress diagram are equivalent to the rectangular stress diagram,and based on the superposition theory and limit equilibrium theory,the formula for calculating the normal section bearing capacity of primary stressed lattice steel reinforced concrete eccentric columns is established,and the results of the formula are in good agreement with the test results.After analyzing the calculation methods of 5 codes in China for the secondary stressed external concrete members,on the basis of the calculation formula of normal section bearing capacity of primary stressed lattice steel reinforced concrete eccentric columns,the formula for calculating normal section bearing capacity of secondary stressed lattice steel reinforced concrete eccentric column is established by data fitting,and the formula calculation results are in good agreement with numerical analysis results.更多还原