考虑二次受力影响的外包钢加固RC梁抗火性能研究
发布时间：2018-10-20 11:33
【摘要】：建筑的改造和维修加固是解决钢筋混凝土结构安全、适用、耐久性,使其满足正常使用需求的重要方式。外包型钢加固法因具有改变结构原有外形小、有效提高承载力和延性、受力可靠、施工简便等优点,而被广泛应用于各种加固工程。由于外包钢靠近加固构件外表面,火灾下极易受到高温影响,因此其耐火性能是一个亟待解决的问题。同时,作为加固构件,二次受力影响不可忽略。基于此,本文在课题组对外包钢加固RC梁耐火极限试验研究的基础上,考虑二次受力影响,对外包钢加固RC梁抗火性能进行研究,并分析了多种参数对二次受力下外包钢加固RC梁抗火性能的影响。主要研究工作及结论如下:(1)利用ABAQUS有限元软件建立了外包钢加固RC梁的温度场有限元分析模型和两种不同情况下外包钢加固RC梁的热-力耦合有限元分析模型,并用试验数据对数值模型的适用性进行了对比验证。(2)运用ABAQUS“杀死-激活”、“单元追踪”的方法,通过不同一次受力水平的横向对比分析,以及不同荷载比的纵向对比分析,分析了考虑二次受力下角钢加固钢筋混凝土梁的抗火性能。结果发现:小荷载比时,二次受力对ASSRC梁火灾过程中的挠度发展可以忽略,而随着荷载比增大,在热力耦合作用下,二次受力效应对结构的影响也越明显;加固梁所承受的第一次荷载水平对耐火极限的影响有限。(3)选取了混凝土强度、梁底纵筋直径、纵筋屈服强度、角钢屈服强度、角钢厚度、角钢宽度、荷载比,保护层厚度、翼缘板厚度、栓杆强度、栓杆布置间距,共计11个参数进行具体计算,分析了解各参数对考虑二次受力外包钢加固RC梁抗火性能的影响。结果发现:荷载比和砂浆保护层是影响二次受力外包钢加固RC梁抗火性能的主要因素,螺栓强度、螺栓间距以及加固角钢厚度的变化对耐火极限的影响很小,其他参数对二次受力外包钢加固RC梁均有不同程度的影响。
[Abstract]:The reconstruction and maintenance and reinforcement of buildings is an important way to solve the safety, applicability and durability of reinforced concrete structures and make them meet the needs of normal use. Because of its advantages of changing the original shape of the structure, improving the bearing capacity and ductility effectively, being reliable and easy to construct, the outsourced steel reinforcement method has been widely used in various reinforcement projects. As the steel is close to the external surface of the strengthened members, it is easy to be affected by high temperature under fire, so its fire resistance is an urgent problem to be solved. At the same time, as a reinforced member, the influence of secondary force can not be ignored. Based on this, the fire resistance of RC beams strengthened with external clad steel is studied in this paper, considering the influence of secondary force, the fire resistance of RC beams strengthened with external clad steel is studied. The influence of various parameters on the fire resistance of RC beams strengthened with steel under secondary loading is analyzed. The main research work and conclusions are as follows: (1) using ABAQUS finite element software, the finite element analysis model of temperature field of RC beam strengthened by wrapped steel and the thermal-mechanical coupling finite element analysis model of RC beam strengthened by wrapped steel under two different conditions are established. The applicability of the numerical model is compared with the experimental data. (2) by using the methods of ABAQUS "kill-activation" and "element tracing", the horizontal comparative analysis of different stress levels and the longitudinal comparative analysis of different load ratios are carried out. The fire resistance of reinforced concrete beams strengthened with angle steel under secondary loading is analyzed. The results show that when the load ratio is small, the deflection development of ASSRC beam during fire can be neglected by the secondary force, but with the increase of the load ratio, the effect of secondary force on the structure is more obvious under the thermal coupling. The effect of the first load level on the fire resistance limit is limited. (3) the concrete strength, beam bottom longitudinal reinforcement diameter, longitudinal steel yield strength, angle steel thickness, angle width, load ratio and cover thickness are selected. The thickness of flange plate, the strength of bolt rod, the spacing of bolting rod are calculated in detail, and the influence of these parameters on the fire resistance of RC beams strengthened with steel under secondary loading is analyzed. The results show that the load ratio and mortar cover are the main factors that affect the fire resistance of RC beams strengthened by secondary load wrapped steel. The change of bolt strength, bolt spacing and the thickness of reinforced angle steel have little effect on the fire resistance limit. Other parameters have different effects on RC beams strengthened with secondary loading steel.
【学位授予单位】：苏州科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375.1
本文编号：2283039
[Abstract]:The reconstruction and maintenance and reinforcement of buildings is an important way to solve the safety, applicability and durability of reinforced concrete structures and make them meet the needs of normal use. Because of its advantages of changing the original shape of the structure, improving the bearing capacity and ductility effectively, being reliable and easy to construct, the outsourced steel reinforcement method has been widely used in various reinforcement projects. As the steel is close to the external surface of the strengthened members, it is easy to be affected by high temperature under fire, so its fire resistance is an urgent problem to be solved. At the same time, as a reinforced member, the influence of secondary force can not be ignored. Based on this, the fire resistance of RC beams strengthened with external clad steel is studied in this paper, considering the influence of secondary force, the fire resistance of RC beams strengthened with external clad steel is studied. The influence of various parameters on the fire resistance of RC beams strengthened with steel under secondary loading is analyzed. The main research work and conclusions are as follows: (1) using ABAQUS finite element software, the finite element analysis model of temperature field of RC beam strengthened by wrapped steel and the thermal-mechanical coupling finite element analysis model of RC beam strengthened by wrapped steel under two different conditions are established. The applicability of the numerical model is compared with the experimental data. (2) by using the methods of ABAQUS "kill-activation" and "element tracing", the horizontal comparative analysis of different stress levels and the longitudinal comparative analysis of different load ratios are carried out. The fire resistance of reinforced concrete beams strengthened with angle steel under secondary loading is analyzed. The results show that when the load ratio is small, the deflection development of ASSRC beam during fire can be neglected by the secondary force, but with the increase of the load ratio, the effect of secondary force on the structure is more obvious under the thermal coupling. The effect of the first load level on the fire resistance limit is limited. (3) the concrete strength, beam bottom longitudinal reinforcement diameter, longitudinal steel yield strength, angle steel thickness, angle width, load ratio and cover thickness are selected. The thickness of flange plate, the strength of bolt rod, the spacing of bolting rod are calculated in detail, and the influence of these parameters on the fire resistance of RC beams strengthened with steel under secondary loading is analyzed. The results show that the load ratio and mortar cover are the main factors that affect the fire resistance of RC beams strengthened by secondary load wrapped steel. The change of bolt strength, bolt spacing and the thickness of reinforced angle steel have little effect on the fire resistance limit. Other parameters have different effects on RC beams strengthened with secondary loading steel.
【学位授予单位】：苏州科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375.1
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