The use of reaction truss is more popular now-a-days since this is simple, quick and less clumsy.

For clayey and silty soils and for loose medium dense sandy soils with N < 15, a 450 mm square plate or concrete block shall be used.

The allowable maximum settlement for warehouse type of structure is 50 mm.

According to National Building Code of India (SP: 7-1970) the differential settlement shall be kept within limits to which the super-structure can accommodate itself without the distortion, by suitably designing the foundation.

For simple spread footing on clayey soils, the allowable pressure should be such that the differential settlement does not exceed 1/300.

The bearing plate is either circular or square, made of mild steel of not less than 25 mm in thickness.

It is suggested that allowable pressure should be selected such that maximum settlement of any individual foundation is 25 mm.

The loading to the test plate may be applied with the help of a hydraulic jack. The reaction of the hydraulic jack may be borne by either any of gravity loading methodor reaction truss method.

Indian standards (IS: 1888: 1982) recommend that the loading of the plate should invariably be borne either by gravity loading platform or by the reaction truss.

A minimum seating pressure of 70 g/cm2 (0.7 t/m2), shall be applied and removed before starting the load test.