JCES Volume 1, Issue 3 September 2012 PP. 102-108 - 102 - Numerical Studies on Blast Loaded Steel-Concrete Composite Panels N. Anandavalli 1 , N. Lakshmanan 2 , J. Rajasankar 3 , Amar Prakash 4 CSIR-Structural Engineering Research Centre, CSIR-Campus, Taramani, Chennai, India 1 anandi@serc.res.in; 2 nlakshmanan@live.com; 3 sankar@serc.res.in; 4 amar@serc.res.in Abstract- In this study, response of Steel-Concrete Composite (SCC) panels subjected to air-blast loading is numerically simulated by conducting finite element analysis. A simplified approach to generate the finite element model of the SCC panels is proposed. In the proposed approach, solid, plate and link elements are used to represent the concrete core, steel cover plates and through-through connectors respectively. Interface between the solid and plate elements are idealized with surface-to-surface contact elements, which take care of the transfer of forces between solid and plate elements. Application of the proposed approach for analyzing the SCC components is validated through two examples. S tatic response of a SCC beam is obtained by using the proposed approach, which is in close agreement with the experimental results. Dynamic response of a SCC panel with through-through connectors subjected to blast pressure due to an explosion of 200 kg TNT at 5 m is obtained by using the proposed simplified approach. Peak response is verified with the results obtained by using an analytical approach. Parametric studies are carried out by varying the charge weight, thickness of the cover plates and diameter of shear connector of the SCC panel. Thickness of the cover plates is found to affect the peak response in a nonlinear manner, while diameter of shear connector is found to have only marginal influence on the peak response. Keywords- Steel-Concrete Composite; Blast Loading; Peak Displacement; Overpressure; Time-History I. INT RODUCTION Structures may experience accidental loads due to blast or impact in addition to other service loads. Blast loads are transient in nature. Peak pressures due to a blast are much greater than that of static collapse load of the structures [1- 3]. Structures have to undergo large deformations in order to resist such load, because elastic design is uneconomical and seldom possible. While undergoing such excessive deformation, they should not lose their integrity as well. Concrete is common construction material that possesses large mass, which is essential in blast resistant construction. However, one of the disadvantages of concrete is possibility of spalling and scabbing. An alternate and cost-effective way is to use structural forms that can improve blast resistance. Some of these forms are layered sacrificial cladding, corrugated metal sandwich cores, fibre-metal laminates and steel-concrete composite construction [4-15]. Among the alternatives, steel-concrete composite (SCC) exhibits promising properties for improved blast resistance [4]. This form of construction combines the characteristics of both the materials, namely, steel and concrete in an efficient manner. It is reported in literature, through experimental and analytical studies on SCC panels, that under static as well as close in detonation, SCC structural components perform relatively better than other structural forms [5-13]. Light weight foam core sandwich panels have been analysed by Andrews and Moussa [13] to evaluate their structural response under air-blast loading. Bi-steel panels comprising of two steel plates that are connected together by an array of friction welded transverse bars have been used in blast-resistant construction [14]. The requirement of minimum core thickness in these types of connectors has led to development of slim light weight Steel-Concrete-Steel (SCS) system with J-hook connectors by Liew and Sohel [15]. Theobald et al. [16] performed a numerical parametric investigation on new type of sandwich panels consisting of tubular structure in protective cladding for blast loading. Influence of tube layout within the panel, tube geometry and top plate geometry on the energy absorption properties of the panel has been determined from the investigation. Numerical investigations on steel-concrete composite structural members are carried out by using the finite element method (FEM). Conventionally, components of the SCC members, namely, concrete core, steel plates / girders and shear connectors are represented by using solid elements [17-20]. In the present study, a simplified finite element modelling approach is proposed for numerical simulation of blast response of SCC panels. The simplified model uses solid, plate and link elements to represent concrete, steel cover plates and shear connectors respectively. Response of a monotonically loaded SCC beam predicted by using the simplified model is found to be in good agreement with that of experimental results, which validates the applicability of simplified model for predicting static response. A SCC panel subjected to air-blast loading is analysed by using the proposed approach. An analytical approach based on equilibrium of forces is used to obtain the peak displacement. This is compared with that of finite element results and is found to be in close agreement, thus validating the proposed approach for dynamic response. This approach is adopted for parametric investigations carried out an SCC panels. Influence of the parameters is studied by comparing the peak response of the panel. II. FINITE ELEMENT MODELLING APPROACH FEM is widely used numerical technique for blast analysis [21-24]. Conventional approach of modelling SCC panel is to employ solid elements to discretize all the components, namely steel, concrete and shear connector