A Novel Modelling Technique for Blast Analysis of Steel-Concrete Composite Panels

AbstractBlast resistant structures usually undergo large plastic deformation and absorb energy before collapse. There are many structural forms that have improved blast resistance are reported in literature. Among these, steel-concrete composite panel has been considered as extremely resilient to blast loading. Conventionally, steel-concrete composite panels are analysed using solid element model for plates, concrete as well as shear connectors. In this paper, a novel modelling technique is proposed for analysis of steel-concrete composite panels under blast loading. As per the proposed technique, shell, solid and link elements are used to model cover plates, concrete and shear connector respectively. Validation and performance studies are carried out with a problem available in literature. The proposed model is found to be better with less demand on modelling requirements. It is also computationally efficient, while retaining the accuracy of results. Parametric studies are carried out using the proposed model on steel-concrete composite panel with through-through connectors subjected to air blast loading. Steel plate thickness, concrete core thickness, connector spacing and diameter of connectors are varied to study their influence on the response behaviour of the panel. It is observed from the study that connector diameter and spacing and core thickness significantly affect the response than the plate thickness

Behaviour of a Blast Loaded Laced Reinforced Concrete Structure

According to existing provisions, large separation distance has to be maintained between two conventional explosive storage structures to prevent sympathetic detonation. In this paper, reduction of the separation distance with the use of earth covered laced reinforced concrete (LRC) storage structure is demonstrated, which will result in saving of land cost. Details of blast resistant design of 75T (NEC) storage structure based on unit risk principle are presented. Performance of the storage structure is evaluated in an actual blast trial. Strain and deflection profiles are obtained from the trial. Based on these, the storage structure is found to be re-usable after the blast trial.Defence Science Journal, 2012, 62(5), pp.284-289, DOI:http://dx.doi.org/10.14429/dsj.62.82

Water Extract from the Leaves of Withania somnifera Protect RA Differentiated C6 and IMR-32 Cells against Glutamate-Induced Excitotoxicity

Glutamate neurotoxicity has been implicated in stroke, head trauma, multiple sclerosis and neurodegenerative disorders. Search for herbal remedies that may possibly act as therapeutic agents is an active area of research to combat these diseases. The present study was designed to investigate the neuroprotective role of Withania somnifera (Ashwagandha), also known as Indian ginseng, against glutamate induced toxicity in the retinoic acid differentiated rat glioma (C6) and human neuroblastoma (IMR-32) cells. The neuroprotective activity of the Ashwagandha leaves derived water extract (ASH-WEX) was evaluated. Cell viability and the expression of glial and neuronal cell differentiation markers was examined in glutamate challenged differentiated cells with and without the presence of ASH-WEX. We demonstrate that RA-differentiated C6 and IMR-32 cells, when exposed to glutamate, undergo loss of neural network and cell death that was accompanied by increase in the stress protein HSP70. ASH-WEX pre-treatment inhibited glutamate-induced cell death and was able to revert glutamate-induced changes in HSP70 to a large extent. Furthermore, the analysis on the neuronal plasticity marker NCAM (Neural cell adhesion molecule) and its polysialylated form, PSA-NCAM revealed that ASH-WEX has therapeutic potential for prevention of neurodegeneration associated with glutamate-induced excitotoxicty

A Simple Technique to Determine Interface Slip of Stud Connected SCC Girders

A simple technique is proposed to compute interface slip of stud connected steel-concrete composite (SCC) girders based on the results of a flexure test. The technique makes use of relative longitudinal displacement of the concrete slab and steel beam to calculate the interface slip. In the flexure test of a SCC girder, a cost-effective instrumentation arrangement consisting of mechanical dial gauges is used to measure the relative longitudinal displacement. Responses measured from experiments on SCC girders conducted by the authors are used for numerical implementation and validation of the technique. Alternatively, interface slip is also evaluated by applying an analytical model which is based on first principles of mechanics. The values of interface slip computed by using the proposed technique are found to have close correlation with those of the analytical model. The effect of edge restraint on slip due to friction between steel and concrete is also studie