Study On Blast-resistant Characteristics Of Reinforced Concrete Structures And Steel Plate Strengthened Reinforced Concrete Composite Structures

In recent two decades, in order to meet the needs of military protecting engineering, civil air defense works and the precaution of deliberate terrorist and accidental explosions, investigation and developments of high-performance anti-blasting structures and reinforcements for existing projects have been an important topic in the field of protective engineering.Considering the blasting prevention purpose of important buildings and civil air defense works, based on finite element method and site explosion tests, this paper studies the blast-resistant characteristics of reinforced concrete structures and steel plate strengthened reinforced concrete composite structures under conditions of non-contact explosions, contact explosions and shallow buried explosions, and reveals the different failure features and mechanisms of these two types of structures. The blast-resistant features of two different arrangement fashion of reinforcement in steel plate strengthened reinforced concrete composite structures are also researched. The main researches and results are as follows:1. Bases on ANSYS/LS-DYNA, the paper researches on the finite element numerical simulation methods of reinforced concrete plate structures and steel plate strengthened structures. It also discusses the critical technical problems of reinforced concrete structure modeling, blast impact loading, fluid-structure interaction analyzing, material constitutive models and parameters selecting, and so on.2. The finite element model for analyzing the blasting dynamic response of slabs under non-contact explosions is established, and the blast-resistant features of reinforced concrete slabs with and without strengthened steel plate are compared and studied. The paper analyzes the non-contact blasting dynamic response features of normal reinforced concrete slab, and discusses the time-history variation and spatial distribution pattern of displacement, stress and strain. The paper also researches on factors affecting slab’s blast-resistant performance and the effect factors. Four different explosion conditions considering different amounts of explosive material are analyzed, which shows that steel plate strengthened structure is better than common reinforced concrete structure in blast-resistant performance, and steel plates play a key role in protecting and reinforcing structures.3. Applying fluid-structure interaction finite element model, the paper analyzes reinforced concrete slab’s local failure mechanism under contact explosion, and expounds its four typical local failure modes with numerical simulation results. According to the explosion stress wave propagation analysis, the failure mechanisms of the blasting crater and damage funnel pit, which locate at the front side facing the explosive and the back side respectively, are revealed..4. The local failure response analyses of ttwo types of steel plate strengthened reinforced concrete composite slabs with different arrangement fashion of reinforcement under both noncontact and contact explosions with different levels of explosive amount are researched. The difference of blast-resistant performances indicates that the blast-resistant performance of the composite slab with the lacing reinforcement acts better in blast-resistant performance than that with stirrup reinforcement.5. The blast-resistant characteristics of two types of steel plate strengthened reinforced concrete composite slabs with different arrangement fashion of reinforcement, are investigated by means of site shallow buried explosions, and their failure phenomena, failure features and their laws their of the slabs are revealed.after explosion. Finite element models for test analysis are established and blasting dynamic responses of the slabs are analyzed. The calculation results reveals slabs may fail in the state of two typical failure patterns, namely “3 plastic hinge” and “4 plastic hinge” under shallow buried explosion in which explosives are set in soil above the composite slab. The blast-resistant characteristics of the slab with acing reinforcement are better than that with stirrup reinforcement.