An applicability of dynamic response analysis of shear-failure type RC beams with lightweight aggregate concrete under falling-weight impact loading

The present study experimentally investigated the pre-failure and post-fatigue behavior of reinforced concrete (RC) beams constructed with lightweight aggregate concrete (LWAC) in comparison with that constructed of normal weight concrete (NWC) of the same compressive strength (40 MPa). A total of twelve RC beams were tested under different fatigue loadings. Based on the experimental observations, the midspan total deflection measured in the fatigue testing consisted of the elastic and plastic components. The mechanismof the two deflection components developed with load cycles was different. The experimental results showed that the fatigue resistance of LWAC beams was better than that of NWC beams for the same fatigue loading levels. It was reflected in both the lower evolution of fatigue damage and the smaller growth of midspan residual deflection. After 2 million cycles, an average increase in residual load capacity of about 8% was found in the NWC beams, while that in the LWA beams remained virtually unchanged.

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Dynamic Response and Shear Demand of Reinforced Concrete Beams Subjected to Impact Loading

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455419500913 ◽

2019 ◽

Vol 19 (08) ◽

pp. 1950091 ◽

Cited By ~ 2

Author(s):

Wuchao Zhao ◽

Jiang Qian

Keyword(s):

Dynamic Response ◽

Impact Loading ◽

Parametric Study ◽

Shear Failure ◽

Impact Force ◽

Rc Beams ◽

Local Response ◽

Shear Demand ◽

The Impact ◽

Peak Impact Force

Reinforced concrete (RC) beams under the impact loading are typically prone to suffer shear failure in the local response phase. In order to enhance the understanding of the mechanical behavior of the RC beams, their dynamic response and shear demand are numerically investigated in this paper. A 3D finite-element model is developed and validated against the experimental data available in the literature. Taking advantage of the above calibrated numerical model, an intensive parametric study is performed to identify the effect of different factors including the impact velocity, impact mass and beam span-to-depth ratio on the impact response of the RC beams. It is found that, due to the inertial effect, a linear relationship exists between the maximum reverse support force and the peak impact force, while negative bending moments also appear in the shear span. In addition, the local response of the RC beams can be divided into a first impact stage and a separation stage. A shear plug is likely to be formed near the impact point at the first impact stage and a shear failure may be triggered near the support by large support forces. Based on the simulation results, simplified methods are proposed for predicting the shear demand for the two failure modes, whereas physical models are also established to illustrate the resistance mechanism of the RC beams at the peak impact force. By comparing with the results of the parametric study, it is concluded that the shear demand of the RC beams under the impact loading can be predicted by the proposed empirical formulas with reasonable accuracy.

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Influence Factors Analysis of RC Beams under Falling Weight Impact Based on HJC Model

Shock and Vibration ◽

10.1155/2018/4731863 ◽

2018 ◽

Vol 2018 ◽

pp. 1-16 ◽

Cited By ~ 2

Author(s):

Xiaohong Long ◽

Ahmed Turgun ◽

Rong Yue ◽

Yongtao Ma ◽

Hui Luo

Keyword(s):

Finite Element ◽

Impact Load ◽

Influence Factors ◽

Response Analysis ◽

Impact Loads ◽

Rc Beams ◽

Element Analysis ◽

Structure Component ◽

Weight Impact ◽

Falling Weight

Impact loads may cause serious or even fatal damage to the structure (component), in most existing specifications in China, and there are no special terms that take impact load into consideration. So, the response analysis of the structure (component) under impact loads is very important. In this paper, the sensitivity analysis was conducted for the 22 parameters of the Holmquist–Johnson concrete (HJC) constitutive model of concrete, and the sensitive parameters of the HJC model are identified with A, B, G, Pl, μl, and fc respectively. LS-DYNA nonlinear transient finite element analysis code was used for this paper. Based on the validation of finite element modeling and choosing midspan deflection of RC beams and impact loads as response indices, some influencing factors on RC beams under falling weight impact were investigated, such as the mass and speed of falling weight, impact position, the strength of concrete and rebar, longitudinal reinforcement ratio, and the span of the beam.

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