Experimental and Numerical Simulation Studies of RC Beams under the Actions of Equal Energy Impact Loads

Xiwu Zhou,Wen Zhang,Runcheng Zhang,Xiangyu Wang,Xinyu Ye

doi:10.1155/2020/8874097

Abstract

In this study, two groups of RC beams were subjected to low-speed drop weight impact test by using the domestic advanced ultrahigh heavy-duty drop weight impact testing machine system. The main aspects studied are the influence of the combination of different impact velocity and mass on the dynamic response and local and global damage change of RC beam under the same impact energy. Next, the numerical model considering material strain rate is established using ABAQUS finite element software to verify and expand the experimental results. The results show the following: (1) under the condition of equal energy, the peak value of impact force measured in this experiment increases with the increase of impact velocity, yet the mid span displacement and rebar strain first increase and then decrease. In addition, when the impact velocity is 2.25 m/s and the impact mass is 400 kg, the beam has the most serious damage; (2) compared with the mass, the impact velocity has more obvious effects on the peak value of cumulative impact force, mid span displacement, and rebar strain; (3) with the decrease of the impact velocity (the increase of the mass), the local damage of the beam is gradually weakened and the overall damage is gradually exacerbated. The failure mode of the beam is transformed from local punching shear failure to overall static failure type.

Highlights

In some special scenarios, RC beams may be impacted by heavy objects during service, such as containers falling from port terminals and stones rolling down mountains [1]
It has been found that the inertial force effects are the key factors which will affect the overall failure of the RC beams, and the size and range of the inertial force distribution are the main reasons for the changes in the overall failure modes of the beams [5]. ese four types of effects jointly impact the mechanical behaviors of the beams under impact load conditions and are quite different from the impacts observed under static load conditions. e influences of impact loads on the impact resistance behaviors of beams have always been a hot topic in this field of research
By comparing the two figures, it could be seen that under the same energy impact load, when the impact velocity increased from 1.84 m/s to 3.18 m/s, the peak impact force of the Group A beam increased by 70% and that of Group B increased by 61%

Summary

Introduction

RC beams may be impacted by heavy objects during service, such as containers falling from port terminals and stones rolling down mountains [1]. Under the conditions of impact loads, material may be subjected to the strain rate effects, and the dynamic constitutive will be quite different from the static constitutive. E strain rate effects will change the strength and stiffness levels of the reinforcements and concrete material, resulting in the bearing capacity of the beams becoming improved when compared with that under static load conditions [2]. Ese four types of effects jointly impact the mechanical behaviors of the beams under impact load conditions and are quite different from the impacts observed under static load conditions. Li [6] used falling weight impact tests and found that the higher the impact velocity is, the more quickly the stiffness of the damaged beams would decrease. It was observed that with enhancements of the strain rate effect, the impact resistance bearing capacity of the beams had increased. Zhou et al [7] carried out falling weight impact tests of stainless-steel concrete beams

Methods

Findings

Discussion

Conclusion