An investigation into adopting different piling systems for integral abutment bridges.
In recent years the use of integral abutment bridges has become increasingly popular, globally. These bridges have many advantages because the super-structure and sub-structure are monolithic in nature, no bearings and expansion joints are required and maintenance is minimal. However these bridges are uncommon in South Africa. The behavioural performance of this type of integral structure is influenced by the movement requirements of the foundations and steel H-piles are generally preferred but H-piles are very rarely used in South Africa due to the high costs. This research work investigates the behaviour and possibility of adopting other commonly used types of piles in South Africa for integral abutment bridges instead of steel H-piles. The research also provides commonly used techniques that are used in practice such as pile sleeving which inherently increases the slenderness of the pile, so the pile can absorb the deck movements. Some of the common challenges regarding integral bridges are considered and appropriate concepts are also presented. The purpose of the research work is also to enlighten the practical bridge designer about integral abutment bridges so important aspects are considered in the design phase. The investigation of different pile types proposed for the integral bridge structure was based on empirical formulae and a desktop study was done. The outcome from the work recommends that steel H-piles on the weaker axis are a superior choice of pile that should be used. Other pile types are also possible such as precast piles, however the designer needs to ensure they perform well under cyclic loading. The work also recommends that a pile sleeve or similar of over 3m long is beneficial to reduce the bending moment and shear force at the point of virtual fixity of the pile. Integral abutment bridges have numerous advantages over conventional bridges, however a carefully thought-out concept of the integral structure must be considered. One important aspect is the length of the integral bridge; to ensure that the structure performs well over its anticipated life span, integral bridges should only be used for short to medium spans.