New technique to protect RC structures against explosions

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Literature review on blast protection by externally bonded FRP reinforcement

One of today’s state-of-the-art techniques is the use of Fibre Reinforced Polymer (FRP) composites as Externally Bonded Reinforcement (EBR). This method consists in gluing strips or flexible sheet in the tension zone to increase the resistance capacity or service behaviour of structures. The use of FRP as externally bonded reinforcement has been demonstrated as a very efficient technique mainly for static load conditions. More recently, a number of studies have also been conducted regarding the use of FRP EBR for strengthening critical infrastructure (concrete and masonry) against blast loading. This paper presents a brief literature review of research on FRP EBR and blast loading and describes the efficiency of FRP composites for blast protection

Experimental study of blast response of RC slabs with externally bonded reinforcement

The present paper discusses experimental work on the efficiency of externally bonded reinforcement (EBR) on reinforced concrete (RC) slabs under blast loads using an explosive driven shock tube (EDST). This study focuses on four tests which have been performed on simply supported RC slabs retrofitted with carbon fiber reinforced polymer (CFRP) strips and subjected to explosions for the same pressure and impulse. Pressure transducers are fixed at the end of the tube to measure the pressure of each experiment. Maximum deflection and strain distribution in the concrete and CFRP strips are recorded using digital image correlation (DIC) measurements. Due the explosion, the RC slabs are submitted to a dynamic vibration in both directions and during the first inbound displacement phase, the kinetic energy of the retrofitted specimen is stored as elastic strain energy in CFRP strips. All this elastic strain energy stored in FRP strips is violently released as kinetic energy during the rebound phase of the slab. The results indicate that EBR increases significantly the flexural capacity and the stiffness of RC slabs under blast loads

Experimental and numerical study of the energy absorption capacity of pultruded composite tubes

A numerical and experimental investigation was carried out in order to evaluate the response of composite tubes, made of poly-vinylester or polyester matrix reinforced unidirectionally with glass fibers, under quasistatic loading. The influence of triggering in failure and energy absorption was investigated. Also a series of finite element models was created using LS-DYNA3D and compared with experimental results. The correlation between simulations and experiments was relatively satisfactory and from the results of the study the energy absorbing suitability of each tube was evaluated. Results would provide more data that are needed for designing effective energy absorption mechanisms subjected under high speed loads

Numerical analysis of debonding between CFRP strips and concrete in shear tests under static and blast loads

The present paper deals with the finite element (FE) analysis of the bond slip between concrete and carbon fiber reinforced polymer (CFRP) strips in a single bond shear test under static loads and in a double bond shear test under blast loading. A plastic damage material model and an elastic material model are used to model the concrete prism and the unidirectional CFRP strip, respectively. The bond interface between concrete and CFRP strip is simulated using a cohesive bond model. For the static loads, the numerical model is validated with experimental tests available in the literature. The debonding failure mode, the delamination loads and the strain distribution along the CFRP strip are predicted. The numerical results show a good agreement with the experimental data using the cohesive bond model. For the blast loads, the validated cohesive bond model is used. A parametric study with respect to the width and the length of the CFRP is conducted. Moreover, the reflected pressure and impulse are varied to highlight the effect of the propagation of the blast wave in the debonding process under blast loads

Non-Destructive Testing Techniques for Corrosion Assessment in Reinforced Concrete Structures in Kenya

Deterioration of concrete structures is inevitable due to the fact that it is subjected to deterring environmental factors. Therefore, inspection and maintenance of these structures should be done to ensure their serviceability. Many concrete structures have been constructed in Kenya. A survey of some of the existing multi-storey buildings shows that even some of the old ones are in good condition; examples are the Norfork Hotel, Sarova Stanley Hotel and the railway bridges built in early 1900s. Yet, ageing structures require periodic monitoring to check their serviceability. Currently, inspection of most structures is done solely by simple visual means which is not always adequate. In order to enhance reliable assessment of structures, the present research introduces non-destructive testing (NDT) techniques for corrosion damage diagnosis in Kenyan concrete structures. Visual inspection is followed by half-cell potential measurements, carbonation tests and chloride tests. Laboratory analysis as well as field testing shows that NDT techniques provide safe, fast and reliable tools for the assessment of structural integrity. Keywords: Reinforced Concrete, Deterioration, Inspection, Non-destructive testin

Comparison of the crushing performance of hollow and foam-filled small-scale composite tubes with different geometrical shapes for use in sacrificial cladding structures

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