【作者】 何平；

【导师】 卜良桃； 王新夏；

【作者基本信息】 湖南大学 ， 土木工程， 2023， 硕士

【摘要】 钢结构建筑在工业与民用建筑中应用广泛,随着服役时间的增长,在复杂工作环境和荷载的耦合作用下,钢构件受损导致承载力和稳定性达不到要求,增加了结构安全事故发生的概率,这一情况的出现亟需对这类钢结构建筑进行加固改造。外包钢筋混凝土加固法是负载下加固钢结构建筑的常用方法之一,但是传统的钢筋混凝土外包加固法由于需要设置钢筋笼并且混凝土中含有粗骨料给负载下加固施工带来极大的不便,加固效果不理想。为改善传统外包钢筋混凝土加固方法的诸多不足,提出一种在不设置纵筋的情况下采用活性粉末混凝土(reactive powder concrete,RPC)围套加固负载型钢柱的方法,本文通过静载试验、有限元分析和理论推导对RPC围套加固负载型钢柱的偏压力学性能和承载力计算方法进行了研究。本文进行的研究内容简述如下:(1)为研究RPC围套加固负载型钢柱的偏心受力性能,设计制作2根型钢对比柱,5根加固柱,通过偏心受压试验,研究了不同加固形式、型钢初始荷载占比(初始荷载/极限荷载)、偏心距对加固柱偏压力学性能的影响。试验结果表明:二次受力过程中,加固层和型钢之间具有可靠的黏结强度,协同工作性能良好,RPC加固层能够显著提高型钢柱的刚度和承载力。(2)借助有限元分析软件ABAQUS通过生死单元法对5根加固柱的二次受力进行了模拟分析,将分析得到的各加固试件的破坏形态、承载力和柱中侧向位移与实际试验结果对比表明模拟结果具有较高的精度。借助已验证的模型进行了参数分析,进一步研究了偏心距、型钢柱初始荷载占比及长细比在更加宽泛的变化范围内对加固柱偏压力学性能的影响。(3)参考国内外现有对负载加固构件的研究,基于平截面假定并且不考虑型钢和加固层之间的黏结滑移推导出了不同型钢初始荷载占比下加固层RPC的强度利用系数。基于极限平衡法,引入推导出的加固层RPC强度利用系数来考虑型钢初始荷载对加固构件带来的不利影响建立了RPC围套加固负载型钢柱的偏心受压承载力计算公式,将5根加固柱的理论计算结果与试验实测结果进行对比发现二者基本吻合,可供该类加固柱的工程设计应用参考。更多还原

【Abstract】 Steel buildings are widely used in industrial and civil buildings.With the growth of service time,under the coupling of complex working environment and load,the steel members are damaged,resulting in the failure of bearing capacity and stability requirements,increasing the probability of structural safety accidents.The emergence of this situation is in urgent need of strengthening and renovation of such steel buildings.The external reinforced concrete reinforcement method is one of the common methods to strengthen steel buildings under load.However,the traditional reinforced concrete external reinforcement method brings great inconvenience to the construction of reinforcement under load due to the need to set up reinforcement cages and coarse aggregates in the concrete,and the reinforcement effect is not ideal.In order to improve many shortcomings of the traditional reinforced concrete method,a method of reinforcing loaded steel columns by using reactive powder concrete(RPC)jacket without setting longitudinal reinforcement is proposed.In this paper,the bias mechanical properties and load capacity calculation method of RPC jacket reinforced loaded steel columns are investigated by static load test,finite element analysis and theoretical derivation.The research conducted in this paper is briefly described as follows:(1)In order to study the eccentric force performance of RPC envelope reinforced loaded steel columns,two section comparison columns and five reinforced columns were designed and fabricated,and the effects of different reinforcement forms,initial load share of sections(initial load/limit load)and eccentric distance on the eccentric mechanical performance of reinforced columns were investigated through eccentric compression tests.The test results show that during the secondary stressing process,the reinforcement layer and the steel section have reliable bonding strength and good synergistic working performance,and the RPC reinforcement layer can significantly improve the stiffness and bearing capacity of the steel section column.(2)The damage pattern,bearing capacity and lateral displacement of the reinforced specimens obtained from the analysis were compared with the actual test results to show that the simulation results have high accuracy.Parametric analysis was conducted with the help of the validated model to further investigate the effects of eccentricity distance,initial load share and length to slenderness ratio of steel sections on the eccentric mechanical properties of reinforced columns over a wider range of variations.(3)Based on the assumption of flat section and without considering the adhesive slip between the steel sections and the reinforcement layer,the strength utilization coefficients of the RPC of the reinforcement layer with different initial load ratios of the steel sections were derived with reference to the existing domestic and foreign studies on the loaded reinforced members.Through the limit equilibrium method,the derived RPC strength utilization coefficient of the reinforcement layer is introduced to consider the adverse effect of the initial load of the steel sections on the reinforced members to establish the eccentric compressive load capacity calculation formula of the RPC envelope reinforced loaded steel columns,and the theoretical calculation results of the five reinforced columns are compared with the experimental measured results to find that they basically agree with each other and can be used for the engineering design application of such reinforced columns.更多还原