مقاله انگلیسی رایگان در مورد مدل سازی عددی از تاثیر با سرعت بالا به پنل بتن مسلح – الزویر 2018

A numerical simulation of a high-velocity impact of reinforced concrete structures is a complex problem for which robust numerical models are required to predict the behavior of the experimental tests. This paper presents the implementation of a numerical model to predict the impact behavior of a reinforced concrete panel penetrated by a rigid ogive-nosed steel projectile. The concrete panel has dimensions of 675 mm
675 mm
200 mm, and is meshed using 8-node hexahedron solid elements. The behavior of the concrete panel is modeled using a Johnson-Holmquist damage model incorporating both the damage and residual material strength. The steel projectile has a small mass and a length of 152 mm, and is modeled as a rigid element. Damage and pressure contours are applied, and the kinetic and internal energies of the concrete and projectile are evaluated. We also evaluate the velocity at different points of the steel projectile and the concrete panel under an impact velocity of 540 m/s.

Introduction

It is well known that concrete is much stronger in terms of compression than in tension. Because of its high compressive strength, and to enhance its tensile strength, tensile reinforcements are added to concrete elements subjected to tensile loading (Rabczuk & Belytschko, 2006; Rabczuk, Akkermann, & Eibl, 2005; Rabczuk, Zi, Bordas, & Nguyen-Xuan, 2008). A concrete material is subjected to static and dynamic loads. The static loads are permanent, whereas the dynamic loads vary over time. Among the dynamic loads, impact loads, which have catastrophic consequences on the structures, are included. An analysis of the impact behavior of reinforced concrete (RC) structures has been of significant interest in recent decades (Diyaroglu, Oterkus, Madenci, Rabczuk, & Rabczuk, 2016; Hu et al., 2017; Kalameh, Karamali, Anitescu, & Rabczuk, 2012; Levi-Hevroni, Kochavi, Kofman, Gruntman, & Sadot, 2018; Rabczuk & Eibl, 2006). Numerous experimental investigations have been carried out on the impact behavior of reinforced concrete structures, through which the compressive strength of concrete has been highlighted to describe its influence on the impact resistance. Many results have shown that the impact resistance of RC concrete is improved when high strength concrete is used (Guo, Gao, Jing, & Shim, 2017; Luccioni et al., 2017). However, Hanchak, Forrestal, Young, and Ehrgott (1992) revealed an exception of this behavior through impact tests applied to concrete slabs penetrated by an ogive-nosed steel projectile using different amounts of unconfined compressive strength, namely, 48 and 140 MPa, and reinforced with 5.69 mm diameter bars. The projectile perforation was undertaken with velocities of 300–100 m/s. The results of the experimental tests showed that an increase in the compressive strength has a minor influence on the impact resistance. Borvik, Langseth, Hopperstad, and Polanco-Loria (2002) carried out experimental ballistic penetration tests on fiberreinforced high-performance concrete slabs penetrated by steel conical-nosed projectiles. The nominal compressive strengths of the concrete slabs were 75, 150, and 200 MPa. It was concluded that the ballistic limit velocity increases to a maximum of 20% even if the unconfined compressive strength of the concrete increases. Li, Wu, Hao, Wang, and Su (2016) studied the brittle behavior of concrete slabs, in which conventional and ultra-high performance concrete with different slab depths and spacing of the principal reinforcements were subjected to a contact explosion. The results showed that ultra-high performance concrete displays an improved resistance compared to conventional concrete. Othman and Marzouk (2016) conducted experimental tests to describe the effects of the steel reinforcement distribution on the dynamic behavior of reinforced concrete plates under impact loads. Their results showed that the impact energy is unaffected by variations in the ratio and distribution of a steel reinforcement when the same impact loads are applied. However, it was found that only the distribution of the steel reinforcement affects the crack pattern and failure mode. Rajput and Iqbal (2017) studied experimentally the ballistic performance of plain, reinforced, and pre-stressed concrete plates subjected to ogive-nosed steel projectiles with a diameter of 19 mm. The velocity applied during their experimental tests varied from 60 to 220 m/s. It was found that the reinforcement minimizes the scabbing and spalling of concrete.