ANALYSIS OF BOX CULVERT - COST OPTIMIZATION FOR DIFFERENT ASPECT RATIOS OF CELL

M.G. Kalyanshetti, S.A. Gosavi

Abstract: Reinforced concrete box culvert consists of top slab, bottom slab and two vertical side walls built monolithically which form a closed rectangular or square single cell. By using one or more intermediate vertical walls multiple cell box culverts is obtained. Multiple cell reinforced box culverts are ideal bridge structure if the discharge in a drain crossing the road is large and if the bearing capacity of the soil is low the single box culvert becomes uneconomical because of the higher thickness of the slab and walls. In such cases, more than one box can be constructed side by side monolithically. In conventional method thickness of box culvert is assumed and later on check for thickness is taken. But this may leads to uneconomical design therefore an attempt is made to evaluate optimum thicknesses for economical design. In the present work 12 m channel length is consider for analysis with 2m to 6m height variation which is again divided into single cell, double cell and triple cell. IRC class AA tracked live load is considered. The analysis is done by using stiffness matrix method and a computer program in C language is developed for the cost evaluation. Study is carried out related to variation in bending moment; subsequently cost comparison is made for different aspect ratios. The percentage reduction in cost of single cell, double cell and triple cell based on optimum thicknesses are presented. The optimum thicknesses presented over here are used to achieve the economical design of box culvert. Based on these optimum thicknesses optimum cost per meter width of single cell, double cell and triple cell is evaluated. The study reveals that the cost of box culvert reduces if the optimum thicknesses which are presented in this study are considered.

Keywords: Box culvert, Single cell, multiple cells, Aspect ratio, Stiffness method

DOI: https://doi.org/10.15623/ijret.2014.0304090