Economic Design of RCC Box Culvert Through Comparative Study of Conventional and Finite Element Method

Abstract

There are several researches already have been done on behavior of reinforced concrete (RC) box culverts in past with different conditions of loads. The design and analysis of box culverts is a complex task. The present era offers the finite element analysis of 3D model of structures, making it easier through software. The conventional methods have been used extensively for design but the use of finite element method (FEM) has not been so popular yet. Finite element analysis of box culvert for parametric studies has been carried out, even for different aspect ratio. Here an effort has been made to show the economic and effective design can be achieved by doing finite element analysis of a box culvert whose concept can be used for large structural design as well. This paper shows the comparative study of analysis of conventional method using STAAD software and of FEM using ANSYS software. A box culvert is a structure consisting two parallel slabs monolithically connected to its vertical slabs allowing an opening for waterways and other ways. The box culverts are ideally suited for the low stream water bodies, railways crossing of high embankments, for road crossing of low or medium traffic density and for the sites where bearing capacity of soil is low. The overall dimension of a box culvert is kept within 4m x 4m due to the fact of synergy deflection [4]. If only one box is implied for the purpose, it is called 'single celled box culvert' and if the purpose requires culvert of more than one box, it is called 'multi-celled box culvert'. A box culvert has many design and installation advantages. One such is that it does not need a separate foundation to be laid on. The bottom slab serves as a raft foundation hence minimizing the pressure on soil. The culvert experiences an up-thrust force from soil which has also been considered in the paper. There are several types of loads acting on a box culvert such as self weight of the culvert, live load on top slab in the form of moving wheel load, earth pressure acting from outside, water and air pressure acting from inside and upward soil thrust on the bottom slab. Hence critical analysis of culvert is necessary to ensure the best service. Box culvert while designing should also follow certain aspect ratio as it is important to obtain an optimum thickness of the slab. Kalyanshetti M. G and Gosavi S [5] have shown in their research that for a certain lengths of the culvert, there are different aspect ratios for obtaining economical design of box culvert. Dynamic effect of moving truck has also been discussed by Chen S. S and Harik I. E in which a time dependent variable dynamic system is solved step by step. Calculations have been made considering parameters like truck velocity, surface roughness, damping ratio, truck culvert frequency ratio and road material. [8] The results found in the paper are uneconomic. Hence this paper can also find the way to make the design of dynamic effects on culvert more economic. Kumar Y. V. and Dr Srinivas C [2] has done a computational anal...

Meshless Analysis of a box culvert resting on Modified Vlasov Foundation

“…Therefore, another model (2D or 3D) considering soil-structure interaction (SSI) is often used to overcome this problem. In this model, the bottom slab is assumed to rest on an elastic foundation, and an SSI model is used to approximate behavior of the foundation soil [11,17]. Some other more sophisticated approaches (2D or 3D) which model the culvert and the soil as a whole system with different constitutive models for soil and structure materials are used in FEM software like ABAQUS, CANDE, and PLAXIS [12].…”