* General Manager ICT Pvt. Ltd., A-9, Green Park, New Delhi – 110 016, e-mail : bnsinha@ictonline.com ** General Manager e-mail : rpsharma@ictonline.com † Written comments on this paper are invited and will be received upto 5 November 2009. Paper No. 555 RCC BOX CULVERT - METHODOLOGY AND DESIGNS INCLUDING COMPUTER METHOD† B.N. SiNha* & R.P. ShaRma** ABSTRACT Culverts are required to be provided under earth embankment for crossing of water course like streams, Nallas across the embankment as road embankment can not be allowed to obstruct the natural water way. The culverts are also required to balance the lood water on both sides of earth embankment to reduce lood level on one side of road thereby decreasing the water head consequently reducing the lood menace. Culverts can be of different shapes such as arch, slab and box. These can be constructed with different material such as masonry (brick, stone etc) or reinforced cement concrete. Since culvert pass through the earthen embankment, these are subjected to same trafic loads as the road carries and therefore, required to be designed for such loads. This Paper deals with box culverts made of RCC, with and without cushion. The size, invert level, layout etc. are decided by hydraulic considerations and site conditions. The cushion depends on road proile at the culvert location. The scope of this Paper has been further restricted to the structural design of box. The structural design involves consideration of load cases (box empty, full, sur- charge loads etc.) and factors like live load, effective width, braking force, dispersal of load through ill, impact factor, co-eficient of earth pressure etc. Relevant IRC Codes are required to be referred. The structural elements are required to be designed to withstand maximum bending moment and shear force. The Paper provides full discussions on the provisions in the Codes, considerations and justiication of all the above aspects on design. Proper design covering these aspects has also been given in the Annexure. To our knowledge, these matters have neither been covered in any text book nor in any special publication at one place. 1 INTRODUCTION It is well known that roads are generally constructed in embankment which come in the way of natural low of storm water (from existing drainage channels). As, such low cannot be obstructed and some kind of cross drainage works are required to be provided to allow water to pass across the embankment. The structures to accomplish such low across the road are called culverts, small and major bridges depending on their span which in turn depends on the discharge. The culvert cover upto waterways of 6 m (IRC:5-1998 1 ) and can mainly be of two types, namely, box or slab. The box is one which has its top and bottom slabs monolithically connected to the vertical walls. In case of a slab culvert the top slab is supported over the vertical walls (abutments/ piers) but has no monolithic connection between them. A box culvert can have more than single cell and can be placed such that the top slab is almost at road level and there is no cushion. A box can also be placed within the embankment where top slab is few meters below the road surface and such boxes are termed with cushion. The size of box and the invert level depend on the hydraulic requirements governed by hydraulic designs. The height of cushion is governed by the road proile at the location of the culvert. This Paper is devoted to box culverts constructed in reinforced concrete having one, two or three cells and varying cushion including no cushion. The main emphasis is on the methodology of design which naturally covers the type of loading as per relevant IRC Codes and their combination to produce the worst effect for a safe structure. The IS:1893-1984² (Clause 6.1.3) provide that box culverts need not be designed for earthquake forces, hence no earthquake forces are considered. Although box of maximum three cells has been discussed but in practice a box culvert can have more cells depending on the requirements at site. Culverts are provided to allow water to pass through Journal of the Indian Roads Congress, October-December 2009 }