Integral Abutment Bridges are bridges without expansion joints in bridge deck. The superstructure is cast integrally with their superstructure. The flexibility and stiffness of supports are designed to take up thermal and braking loads.
The design of Integral Abutment Bridges is simple as it may be considered as a continuous fame with a single horizontal member with two or more vertical members. The main advantage of this bridge form is jointless construction which saves the cost of installation and maintenance of expansion joints and bearings. It also enhances better vehicular riding quality. Moreover, uplift resistance at end span is increased because the integral abutment serves as counterweight. As such, a shorter end span could be achieved without the provision of holding down to expansion joints. The overall design efficiency is increased too as the longitudinal and transverse loads on superstructure are distributed over more supports.
However, there are potential problems regarding the settlement and heaving of backfill in bridge abutment. For instance, “granular flow” occurs in backfill materials and it is a form of on-going consolidation. Settlement of backfill continues with daily temperature cycles and it does not stabilize. Active failure of upper part of backfilling material also occurs with wall rotations. This leads to backfill densification and can aggravate settlement behind the abutment.
This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.