Effect of Modulus of Subgrade Reaction on Structural behaviour of Integral Bridge

Abstract

Integral Abutment Bridges (IABs) are joint less and bearing less bridges whereby the deck is continuous and
monolithic cast with abutment walls. The behaviour of Integral abutment bridge is interdependent between its structural
components and soil medium, because complex behaviour of soil. IABs are complex structures due to the nonlinearity and
uncertainties in bridge materials and soil boundaries. Modulus of subgrade reaction (Ks) of soil is the bearing capacity per
unit settlement.
The present work includes the modelling of Integral abutment bridges with simple springs stiffness for the analysis. The
bridge length is 50m, consists of two lanes and two spans of 25m each analyze as per IRC guidelines. Temperatures change
daily and seasonally the lengths of integral bridges increase and decrease, pushing the abutment against the approach fill and
pulling it away. As a result, the bridge super-structure, the abutment and foundation soil are all subjected to cyclic loading,
and understanding their interactions is important for effective design and satisfactory performance of integral bridges.
Applying the earth pressure loads is to assign appropriate spring stiffness to the abutment to represent the soil properties. The
earth pressure on the abutments can be considered using appropriate pressure coefficient Ks with different soil types.
Depending on the soil conditions, the forces generated in the structure can vary significantly. Effect of loose, medium and
dense sand soil stiffness is carried out for study of structural response of integral bridge. The final aim of this study is to
propose modelling of integral abutment bridge system with influence of modulus of subgrade reaction which can allow
predictions of dynamic response based on the results of static relative displacement studies coupled with simple soil stiffness
subjected to the dynamic loading using standard software SAP series Csi bridge.