火灾后钢管活性粉末混凝土柱抗爆性能及破坏评定方法研究

As a new fire-resistant and blast-resistant composite structural member that would be widely applied in practical engineering, reactive powder concrete filled steel tube is usually used as the main member of important engineering. Present investigations indicated that the advantages of steel tube and reactive powder concrete each other and the synergistic effects of reactive powder concrete filled steel tube could be exerted to resisted to blast load,but it was still necessary to investigate into the blast-resistant capacities after exposure to fire. The current researchs shown that all kind of static capabilities of concrete filled steel tube after exposure to fire were degenerated due to high temperature effects, but the blast-resistant mechanisms were unclear for they involved the coupling influences of temperature effects, strain rate effects, inertia effects and high frequency component of blast load. In this investigation, researchs on the variation law of stress wave characteristic, failure mode, strength and energy dissipation for reactive powder concrete and reactive powder concrete filled steel tube are carried out by means of Split Hopkinson Pressure Bar Test, and the material dynamic constitutive relations including the influences of fired condition and strain rate are seriously established. The influences of the factors such as fired time,dynamic load characteristic and structural characteristic on the blast-resistant capacities of reactive powder concrete filled steel tubular columns after exposure to fire are first analyzed by the associative approachs of model test, numerical simulation and theoretical analysis. The essential mechanisms of dynamic deformation and failure would be revealed, the failure assessment method and the relevant reinforce recover technology according to the pressure-impulse curves would also be given. The theoretical references for studies on the blast-resistant capacities of reactive powder concrete filled steel tube and its engineering application are presented in this investigation.

钢管活性粉末混凝土（钢管RPC）是一种极具应用前景的新型抗火抗爆组合结构，常用作重大工程的承重构件。最新研究发现钢管RPC可发挥钢管与RPC各自优势及其协同作用抵抗爆炸荷载，但火灾后抗爆性能需进一步探索。已有研究显示，火灾后钢管混凝土各项静力性能因高温效应均明显退化，但因涉及温度效应、应变率效应、惯性效应及荷载高频分量的耦合影响，其抗爆机理尚不清楚。本项目首先通过SHPB动态压缩试验研究RPC及钢管RPC的应力波动特征、破坏模式、强度及耗能能力的变化规律，着重构建考虑受火条件和应变率影响的材料动态本构关系模型。在此基础上首次采用模型试验、数值模拟和理论分析相结合途径研究受火时间、动荷载特征和结构特性等因素对火灾后钢管RPC柱抗爆性能的影响规律，重点揭示动力变形与破坏的内在机理，并提出基于P-I曲线的破坏程度评估方法及相应的加固修复技术。该研究为探讨钢管RPC抗爆性能及工程应用提供理论参考。

钢管活性粉末混凝土（Reactive Powder Concrete-Filled Steel Tube，钢管RPC）具有承载力高、刚度大、塑性好等优点在抗火抗爆结构中展现了良好的应用前景。然而，钢管RPC在正常使用期间，除了承受常规设计静载外，还可能承受火灾或爆炸等极端荷载的作用，因此探索其抗爆性能和破坏机理具有重要的工程意义。项目围绕火灾后钢管RPC柱的抗爆性能较系统地开展了理论分析、试验研究和数值模拟。主要工作和结论如下：.（1）对高温后钢管RPC进行SHPB试验，探究温度效应和应变率效应对钢管RPC动态力学性能的影响，在此基础上进一步得到钢管RPC的韧性、相对韧性、能量吸收率、动力提高系数与温度和应变率的关系，并提出冲击荷载作用下高温后钢管RPC极限强度的预测公式。.（2）利用ANSYS对高温下钢管RPC温度场进行数值模拟，在此基础上采用加权平均法得到高温后钢管RPC静态组合强度，并分析高温后动力提高系数及高温后钢管RPC极限强度，结果表明高温后钢管RPC极限强度预测值与试验值吻合较好。.（3）建立了火灾后钢管RPC柱残余力学性能简化计算方法，并在公式中考虑了温度效应对钢管RPC套箍约束作用的影响，在此基础上采用等效单自由度法对不同高温后柱的动力响应进行了弹塑性动力分析。.（4）通过4根大比例钢管RPC柱试件的野外抗爆试验，得到了冲击波反射超压和钢管RPC柱的位移、应变时程曲线，分析了受火时间和比例距离对火灾后钢管RPC柱抗爆性能的影响。.（5）开展了火灾、爆炸作用后钢管RPC柱残余承载力试验，剖析了受火时间和爆炸荷载对钢管RPC柱损伤程度的影响，通过试验验证了火灾后钢管RPC柱残余承载力计算公式的可靠性。.（6）采用LS-DYNA软件对火灾后钢管RPC柱动态响应全过程进行了模拟，并通过试验数据验证了其有效性，采用参数化分析方法研究了荷载参数（受火时间、爆炸荷载、轴向荷载）、几何参数（含钢率、长细比）和材料参数（钢材强度）对火灾后钢管RPC柱抗爆性能的影响规律。