Development of impact-resistant design procedure of RC members using relationships among static bending/shear capacity, input energy, and absorbed energy

为了建立静弯破坏模式和剪切破坏模式下钢筋混凝土梁的合理抗冲击设计程序，以钢筋比、剪跨比、截面尺寸和钢质量为变量，对不同类型的矩形钢筋混凝土梁进行了落锤冲击试验。采用200、300、400 kg三种不同质量的钢种，采用迭代加载法和单次加载法两种加载方式对简支梁跨中施加冲击载荷。在本实验中，通过宽带模拟数据记录仪测量并记录钢筋自重产生的冲击力、支撑点处的反力以及钢筋混凝土梁的位移。另一方面，为了建立合理的弯曲破坏型和剪切破坏型RC梁在冲击荷载作用下的数值分析方法，采用三维有限元法对RC梁进行了弹塑性冲击响应分析。通过与实验结果的比较，讨论了基于简单本构律的方法的适用性。研究结果表明：1)弯曲破坏型和剪切破坏型RC梁在冲击荷载作用下的极限强度可以用破坏时的最大反力来估计；2)根据梁极限状态下最大反力、吸收能量和跨中残余位移之间的关系，提出了弯曲破坏型和剪切破坏型RC梁的抗冲击设计公式。并通过实验结果验证了它们的实用性；3)采用本文提出的简单有限元分析方法，可以准确预测RC梁的冲击力、反作用力和位移时程。利用最大主应力分布可以预测钢筋混凝土梁侧面的裂缝形态。少

In this study, to establish a rational impact-resistant design procedure of Reinforced Concrete(RC)beams with statically bending-failure-mode and shear-failure-mode, falling-weight impact tests on various kinds of rectangular RC beams are conducted in which rebar ratio, shear-span ratio, cross sectional dimensions, and mass of steel weight are taken as variables. Impact load is surcharged onto the mid-span of simply supported RC beams using three kinds of steel weights varying mass : 200, 300, and 400 kg and applying two types of loading methods : iterative loading method and single loading method. In this experiment, impact force occurred in the steel weight, reaction force at support points, and displacements of RC beams are measured and recorded by wide-band analog data recorder.On the other hand, to establish a rational numerical analysis method for bending-failure-type and shear-failure-type RC beams under impact loading, elasto-plastic impact response analyses on RC beams are car … More ried out by means of three-dimensional Finite Element Method(FEM). The applicability of the proposed method using a simple constitutive law is discussed comparing with the experimental results mentioned above.The results obtained from this study are as follows : 1)Ultimate strength of bending-failure-type and shear-failure-type RC beams subjected to impact load can be estimated by using the maximum reaction force at failure ; 2)The impact-resistant design formulas for bending-failutre-type and shear-failure-type RC beams are empirically proposed using relationships among the maximum reaction force, absorbed energy, and residual displacement of the mid-span of beam at ultimate state. And theirs practical applicability is confirmed comparing the experimental results ; 3)Time histories of impact force, reaction force, and displacements of RC beams can be accurately predicted by means of the proposed simple FE analysis method. And also, crack patterns generated in the side-surface of RC beam can be predicted from maximum principal stress distribution. Less