Dynamic Response And Damage Assessment Of Reinforced Concrete Slabs Under Close-in Blast Loading

As the main component of frame structure,reinforced concrete slab is easily to be damaged because of its own characteristics.Its damage may cause the loss of lateral support of important structural components such as beams and columns,leading to serious consequences such as continuous collapse of the structure.At the same time,through the analysis of previous explosion accidents,we find that the probability of closein explosion accidents is more possible to happen and the damage is more serious,which seriously threatens the safety of people's lives and property.The reinforced concrete slabs under the close-in blast loading are analyzed in numerical simulation by using ANSYS/LS-DYNA explicit dynamic analysis software.The damage curve of W-R is established to evaluate the damage of reinforced concrete slabs subjected under close-in blast loading.Provide some suggestions for the development of antiknock specification.The main contents of this paper is as follows:(1)According to the characteristics of large plastic deformation properties of reinforced concrete slabs under close-in blast loading,the deflection surface function is reasonably assumed,and the load non-uniformity coefficient(?)of reinforced concrete slabs under four-sided fixed support condition is obtained by using the virtual work principle.The non-uniformity of surface load can be well described by using the value of ?.The load non-uniformity coefficient and equivalent static load method are used to calculate the maximum dynamic response of a slab subjected to close-in blast loading.(2)In order to ensure the correctness of the material model and the modeling method used in the finite element simulation process,this paper first simulates an experiment.By comparison,it is found that the results of finite element simulation coincide better with the experimental results.Relevant material models and modeling methods can be used for the finite element simulation of reinforced concrete slabs under close-in blast loading.(3)The numerical analysis model of reinforced concrete slabs with four edges fixed edges is established.Under blast loading,the distribution of blast loads on the face of blasting is obtained,and the value of ? is calculated.The influential parameters of ? are analyzed.The displacement and stress nephograms are obtained,and the possible damage and crack areas under blast loading are analyzed.The influence of parameters on dynamic response under different conditions is obtained by changing the compressive strength of concrete,yield strength of steel bar,diameter of steel bar and thickness of slab.The sensitivity of parameters under two typical boundary conditions fixed and simply supported is also analyzed.The major influential parameters to improve the blastresistance of reinforced concrete slabs are obtained.(4)The damage assessment criterion of reinforced concrete slab under blast loading based on the support rotation is applied.According to the characteristics of close-in blast loading,the weight-range(W-R)curve is used to describe the damage of components,and the W-R curve and curve fitting formula of reinforced concrete slabs under close-in blast loading are further obtained,and the fitting formula is verified by finite element method.Finally,the effects of various parameters on the damage curves of plates with different damage grades are studied.