scholarly journals Blast Loading Response of Reinforced Concrete Panels Externally Reinforced with Steel Strips

2019 ◽  
Vol 4 (3) ◽  
pp. 54
Author(s):  
Rizwan Khan ◽  
Syed Hassan Farooq ◽  
Muhammad Usman
Keyword(s):  
Blast Loading ◽  
Front Face ◽  
Economic Losses ◽  
Structural Wall ◽  
Existing Structures ◽  
Steel Strips ◽  
Military Installation ◽  
Wall Panels ◽  
Blast Effect ◽  
Strengthening Technique

Frequent terrorist activities, the use of vehicle bomb blasts and improvised explosive devices (IEDs) have brought forth the task of protection against blasts as a priority issue for engineers. Terrorists mostly target the areas where human and economic losses are significantly higher. It is really challenging to study the effects of blast loading on structures due to numerous variables. For instance, the type of detonation charge, explosive material, placement of charge and standoff distance, etc., are a few of the variables which make the system more complicated. Reinforced cement concrete (RCC) wall panels are commonly used for protecting important installations and buildings. In this research, the response of RCC wall panels has been investigated due to the blast effect caused by two TNT charge weights of 50 kg and 100 kg. These two charge weights have been selected after a detailed study of terrorist activities in the recent past. For this purpose, an existing arrangement at an important military installation, i.e., NESCOM Hospital Islamabad in Pakistan, has been selected. To reduce computational efforts, three RCC wall panels, placed side by side producing a continuous front along with a corresponding boundary and structural wall, have been considered. RCC wall panels are placed at a distance of 3 ft from the perimeter of the boundary wall and 23 ft from the structural wall. The displacement on the front face of RCC wall panels and the structural wall is measured at three levels of top, middle and bottom. ANSYS AUTODYN software has been used to simulate the model. Analysis has been carried out to identify and study the weakness of existing arrangements. Literature was reviewed for suggesting an appropriate strengthening technique for existing structures against blast loading. It was found that in addition to existing strengthening techniques, use of steel strips is amongst the most feasible technique for strengthening existing structures. It not only significantly enhanced the blast performance of structures, but it also significantly reduced z-direction displacements and pressures. The results show that the use of steel strips as the improvement technique for already placed RCC wall panels can be effective against a blast loading of up to 100 kg TNT.

scholarly journals Experimental Characterization of the FRCM-Concrete Interface Bond Behavior Assisted by Digital Image Correlation

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1154
Author(s):  
Dario De Domenico ◽  
Antonino Quattrocchi ◽  
Damiano Alizzio ◽  
Roberto Montanini ◽  
Santi Urso ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Mechanical Tests ◽  
Image Correlation ◽  
Front Face ◽  
Full Field ◽  
Bond Behavior ◽  
Externally Bonded ◽  
Strengthening Technique ◽  
Concrete Interface

Digital Image Correlation (DIC) provides measurements without disturbing the specimen, which is a major advantage over contact methods. Additionally, DIC techniques provide full-field maps of response quantities like strains and displacements, unlike traditional methods that are limited to a local investigation. In this work, an experimental application of DIC is presented to investigate a problem of relevant interest in the civil engineering field, namely the interface behavior between externally bonded fabric reinforced cementitious mortar (FRCM) sheets and concrete substrate. This represents a widespread strengthening technique of existing reinforced concrete structures, but its effectiveness is strongly related to the bond behavior between composite fabric and underlying concrete. To investigate this phenomenon, a set of notched concrete beams are realized, reinforced with FRCM sheets on the bottom face, subsequently cured in different environmental conditions (humidity and temperature) and finally tested up to failure under three-point bending. Mechanical tests are carried out vis-à-vis DIC measurements using two distinct cameras simultaneously, one focused on the concrete front face and another focused on the FRCM-concrete interface. This experimental setup makes it possible to interpret the mechanical behavior and failure mode of the specimens not only from a traditional macroscopic viewpoint but also under a local perspective concerning the evolution of the strain distribution at the FRCM-concrete interface obtained by DIC in the pre- and postcracking phase.

Numerical investigation on the dynamic response of foam-filled corrugated core sandwich panels subjected to air blast loading

2017 ◽  
Vol 21 (3) ◽  
pp. 838-864 ◽  
Author(s):  
Yuansheng Cheng ◽  
Tianyu Zhou ◽  
Hao Wang ◽  
Yong Li ◽  
Jun Liu ◽  
...  
Keyword(s):  
Total Energy ◽  
Energy Absorption ◽  
Sandwich Panels ◽  
Blast Loading ◽  
Front Face ◽  
Back Side ◽  
Air Blast ◽  
Foam Filled ◽  
Blast Performance ◽  
Air Blast Loading

The ANSYS/Autodyn software was employed to investigate the dynamic responses of foam-filled corrugated core sandwich panels under air blast loading. The panels were assembled from metallic face sheets and corrugated webs, and PVC foam inserts with different filling strategies. To calibrate the proposed numerical model, the simulation results were compared with experimental data reported previously. The response of the panels was also compared with that of the empty (unfilled) sandwich panels. Numerical results show that the fluid–structure interaction effect was dominated by front face regardless of the foam fillers. Foam filling would reduce the level of deformation/failure of front face, but did not always decrease the one of back face. It is found that the blast performance in terms of the plastic deflections of the face sheets can be sorted as the following sequence: fully filled hybrid panel, front side filled hybrid panel, back side filled hybrid panel, and the empty sandwich panel. Investigation into energy absorption characteristic revealed that the front face and core web provided the most contribution on total energy absorption. A reverse order of panels was obtained when the maximization of total energy dissipation was used as the criteria of blast performance.

scholarly journals Dynamic Response of RC Panel with and Without Openings Subjected To Blast Loading

2019 ◽  
Vol 8 (10) ◽  
pp. 2535-2549
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Response ◽  
Blast Loading ◽  
Blast Load ◽  
Front Face ◽  
Charge Weight ◽  
Plasticity Model ◽  
Rear Face ◽  
Peak Displacement ◽  
Concrete Damaged Plasticity

The dynamic response of reinforced concrete (RC) panels without and with different configuration of opening under blast load scenario is investigated in the present study. The numerical simulations were carried out using finite element method with ABAQUS application. The concrete behavior under blast loading was modelled using Concrete damaged plasticity model. The material parameters for concrete damaged plasticity model were determined using methodology proposed by [14]. The parametric study was carried out using variation in blast load due to different charge weight. It was observed that the peak displacement increases with increase in blast load. It was also observed that at lower blast load, failure of reinforced concrete panel was initiated by cracking at rear face of panel but as the blast load increases the RC panel was failed by combination of crushing of front face of panel along with cracking of rear face. It was observed that for the given blast load, the RC panel without opening is less affected by crushing failure as compared to RC panel with opening configuration studied. It was also observed that the RC panel with circular opening at center is stiffer than other opening configuration and observed to have stable structural performance against the blast load studied.

scholarly journals Post-strengthening of reinforced concrete beams with prestressed CFRP strips. Part 1: analysis under static loading

2012 ◽  
Vol 5 (3) ◽  
pp. 343-361
Author(s):  
M. R. Garcez ◽  
G. L. C. P. Silva Filho ◽  
Urs Meier
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Experimental Studies ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Existing Structures ◽  
Flexural Tests ◽  
Strengthening Technique ◽  
Epoxy Matrices

Different FPR post-strengthening techniques have been developed and applied in existing structures aiming to increase their load capacity. Most of the FRP systems used nowadays consist of carbon fibers embedded in epoxy matrices (CFRP). Regardless of the advantages and the good results shown by the CFRP post-strengthen technique, experimental studies show that, in most cases, the failure of post-strengthened structures is premature. Aiming to better use the tensile strength of the carbon fiber strips used as post-strengthening material, the application of prestressed CFRP strips started to be investigated. The main purpose of this paper is to analyze the effects of the composite prestressing in the performance of the CFRP post strengthening technique. The experimental program was based on flexural tests on post-strengthened reinforced concrete beams subjected to static - part 1 and cyclic - part 2 loading. Experimental results allowed the analysis of the quality and shortcomings of post-strengthen system studied, which resulted in valuable considerations about the analyzed post-strengthened beams.

scholarly journals Numerical Investigation of the Dynamic Responses and Damage of Linings Subjected to Violent Gas Explosions inside Highway Tunnels

2018 ◽  
Vol 2018 ◽  
pp. 1-20 ◽  
Author(s):  
Zhipeng Li ◽  
Shunchuan Wu ◽  
Ziqiao Cheng ◽  
Yibo Jiang
Keyword(s):  
Numerical Simulation ◽  
Blast Loading ◽  
Damage Mechanism ◽  
Relevant Information ◽  
Dynamic Responses ◽  
Economic Losses ◽  
Future Research ◽  
Gas Explosion ◽  
Empirical Formulas ◽  
Fully Coupled

The linings of structures suffer severe damage when subjected to internal explosions, which cause numerous casualties and incalculable economic losses. In this paper, a violent gas explosion that occurred inside a highway tunnel in the city of Chengdu, China, is studied through numerical simulations. The evaluated energy of the gas explosion was equivalent to 2428.9 kg of TNT. A fully coupled numerical model consisting of five parts is established with dimensions consistent with the real prototype dimensions and by considering fluid-structure interaction (FSI) effects. Then, a detailed modelling process is presented and validated through a comparison with empirical formulas. This paper investigates the strength and propagation characteristics of a blast shock wave inside the tunnel, and both the effective stresses and dynamic responses of the lining are analysed under the blast impact loading. The damage mechanism is studied, and the evolution of the lining damage is reproduced, the results of which show good agreement with the actual conditions. Moreover, in terms of the responses and damage of the lining, the fully coupled blast loading model has obvious advantages in comparison with the simplified blast loading model. Furthermore, the damage assessment of the lining conducted using the single degree of freedom (SDOF) method agrees well with the results of the numerical simulation and site investigations. The comprehensive numerical simulation technique used in the present paper and its results could represent valuable references for future research on violent explosions within tunnels or very large underground structures and provide relevant information for the blast-resistant design of such structures.

Pumice concrete for structural wall panels

2003 ◽  
Vol 25 (1) ◽  
pp. 115-125 ◽  
Author(s):  
L. Cavaleri ◽  
N. Miraglia ◽  
M. Papia
Keyword(s):  
Structural Wall ◽  
Wall Panels

scholarly journals Numerical Analysis of Dynamic Response of Corrugated Core Sandwich Panels Subjected to Near-Field Air Blast Loading

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Pan Zhang ◽  
Yuansheng Cheng ◽  
Jun Liu
Keyword(s):  
Dynamic Response ◽  
Failure Modes ◽  
Near Field ◽  
Three Dimensional ◽  
Sandwich Panels ◽  
Blast Loading ◽  
Front Face ◽  
Air Blast ◽  
Solid Plate ◽  
Air Blast Loading

Three-dimensional fully coupled simulation is conducted to analyze the dynamic response of sandwich panels comprising equal thicknesses face sheets sandwiching a corrugated core when subjected to localized impulse created by the detonation of cylindrical explosive. A large number of computational cases have been calculated to comprehensively investigate the performance of sandwich panels under near-field air blast loading. Results show that the deformation/failure modes of panels depend strongly on stand-off distance. The beneficial FSI effect can be enhanced by decreasing the thickness of front face sheet. The core configuration has a negligible influence on the peak reflected pressure, but it has an effect on the deflection of a panel. It is found that the benefits of a sandwich panel over an equivalent weight solid plate to withstand near-field air blast loading are more evident at lower stand-off distance.

Light Weight Composite for Structural Wall Panels

2015 ◽  
Vol 2 (4-5) ◽  
pp. 2928-2937 ◽  
Author(s):  
S. Geetha ◽  
Selvakumar Madhavan
Keyword(s):  
Light Weight ◽  
Structural Wall ◽  
Wall Panels
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