Steel grillage fondation

building construction type of shallow foundation.

1. STEEL GRILLAGE FONDATION Presented By : Name : Komal Prasad Roll No : 1405003 Semester : 4 th Dept. of Architecture N.I.T. PATNA

2. INTRODUCTION A Grillage foundation is a special type of isolated footing, generally provided for heavily loaded steel stanchions. It is a type of shallow foundation. It is used in the location where safe bearing capacity of soil is very poor . Its name define its function and structure as it is made up of steel beams, structurally known as rolled steel joist. It may also be provided for masonry walls.

3. METHOD OF CONSTRUCTION The depth of foundation is limited from 1m to 1.5m , as its a type of shallow foundation. However it should not be less then 90 cm. Steel beams are provide in two or more tiers, the top tier of grillage beam is laid at right angles to the bottom tier. The beam of each tier are held in position by 20 mm diameter spacer bars with 25 mm diameter pipe separators.

4. METHOD OF CONSTRUCTION The grillage beam are then embedded in concrete , a minimum gap of 8cm is kept between beams so the concrete can be easily poured and properly compacted. After levelling the base and pouring the concrete its should be checked that compaction is done properly and formed an impervious layer of thickness not less than 15 cm. This protect steel joist from groundwater, which can cause corrosion. Then the first layer of beams are laid over concrete bed at a distance of 100mm to 300mm, with the help of pipe separators. The upper surface of all the steel beams should lies in one horizontal plane.

5. METHOD OF CONSTRUCTION Rich cement grout is poured all around the lower flanges of the beam so that they are secured to the concrete bed. Concrete is poured between and around the beams of first of first tier. The second tier of beam is then placed at the right angle to the first tiers and over the top flanges of the beams of the first tier. They are properly spaced with the help of pipe separators

6. METHOD OF CONSTRUCTION Concrete is then poured between and around the steel beams. The steel stanchions is then connected to the upper tier with the help of a base plate, side angles, and a gusset plate. These connecting elements are also embedded in the concrete so that joint become rigid.

7. PRECAUTION TO BE TAKEN The depth of footing should not be less than 90cm. The distance between the flanges should not exceed 30cm so that filled concrete acts monolithically with the beams. The concrete filling should not carry any load ; its simply keeps the beams in the position. A minimum gap of 10cm is kept on the outer side of the external beam, as well as the upper flanges of top tier. The depth of concrete below lower tier should be atlest 15cm.

8. PLAN OF STEEL GRILLAGE

9. ELEVATION AND SECTION

10. VIEW OF ELEMENTS OF FOOTING

11. BIBLIOGRAPHY Book Building Construction by Dr. B.C. Punmia, Ashok Kumar Jain and Arun Kumar Jain. Google ; Wikipedia Class work sheets.

12. THANK YOU