Finite element analysis of impact-perforated reinforced concrete slabs

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Insinööritieteiden korkeakoulu | Master's thesis
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Date

2017-12-11

Department

Major/Subject

Structural Engineering

Mcode

ENG3039

Degree programme

Master's Programme in Structural Engineering

Language

en

Pages

64

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Abstract

The safety of the workers and durability of structures against the impact of low-velocity falling weights is of significant importance in construction industry, especially for construction of multi-storey buildings. The empirical formulae for the estimation of the impact behavior of reinforced concrete are limited to the domain settings in which they are generated and are originally developed for high-speed velocity impacts less relevant to the construction industry. This study presents a finite element analysis procedure for the impact analysis of reinforced concrete slabs under low-velocity and high-mass impacts using the Abaqus/Explicit solver. A modified Concrete Damage Plasticity material model with strain rate effects and a physically motivated element deletion criterion has been used for modelling concrete and strain-rate-dependent elastoplastic damage model is utilized for modelling the reinforcement. A three dimensional Langrangian formulation and eight-node hexahedron elements with reduced integration are used for modelling concrete. The reinforcement is discretized with two-node beam elements. The numerical analysis is compared against three experimental impact tests carried out at Heriot-Watt University. In terms of perforation and the velocity-history of the impactor, the numerical results are found to be accurate. The validated finite element procedure is then used to estimate the minimum velocity of the impactor required to perforate, in the sense of the so-called ballistic limit, a 150 mm thick two-layer reinforced concrete slab for impactor weights 250 kg, 500 kg and 1000 kg. The obtained ballistic limits are compared to the empirical formula of UK Atomic Energy Authority: a very good correlation has been obtained, adding a second layer of validation onto the numerical procedure.

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Supervisor

Niiranen, Jarkko

Thesis advisor

Raiskila, Markku
Fedoroff, Alexis

Keywords

finite element method, impact, reinforced concrete slab, perforation, concrete damage plasticity, abaqus/explicit

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https://urn.fi/URN:NBN:fi:aalto-201712188134

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