Grand Wisata Cable-Stayed Overpass, Indonesia

The Grand Wisata cable-stayed overpass is located in the Eastern Bekasi, around 20 km from Jakarta. The construction was completed in May 2007, and was opened for traffic in July 2007. The overpass has a span length of 81 m, and was designed mainly for aesthetics. It consists of a single pylon with two inclined concrete columns being interconnected by an arch at the top, and precast prestressed concrete girders over-crossing an expressway. Due to a 3D inclination and the non-prism shape of the pylon's sections, a full-support scaffolding system was used for concrete pouring on the 40-m high pylon. Care in the designing of the scaffolding has been taken in particular to resist the lateral forces induced by the pylon's own weight during the concreting, while a step-by-step deflection analysis was performed to accommodate the pylon's deformation during construction. Due to the hollow and non-prismatic shape of the pylon's sections, in particular the top arch connection, special care was taken with regard to the compaction of the concrete. In this respect, a high-performance and self-compacting type of concrete of 60 MPa cylindrical strength, with a slump flow criteria of 650–750 mm, was used for the pylon's concreting, which at this moment represents the highest grade of self-compacting concrete ever having been produced in Indonesia for the cast-in-place concreting practice. Due to limited space in the middle of the expressway, and to install a temporary support for erecting the precast girders, a multistage stressing process on the stay cables was designed to adapt the maximum reaction forces allowed by the temporary support. A special design was also applied to the manufacture of the main precast girders that should have a slightly parabolic alignment, in order to accommodate the design camber of the deck.