A case study of a partially pre-stressed multi-storey building incorporating fast-track construction

Abstract

This paper presents a case study of the construction of a partially pre-stressed multi-storey office block in Adelaide, Australia. The designers and construction managers faced numerous issues involving the construction speed and performance of the nine storey building, in particular the performance of the two-way partially pre-stressed suspended slabs. The planned construction period was an absolute minimum due to a contract for early occupancy and high daily costs of construction equipment. Excessive deflections of the 9.6 m × 8.4 m × 200 mm thick slabs were a concern for this fast-track construction. This situation created some significant issues to ensure satisfactory construction speed and acceptable deflection levels. This paper discusses these issues while also explaining and documenting the steps taken to obtain the final solution. A large collection of data from the construction process is presented. An emphasis is placed on the material properties of the concrete slabs, namely compressive strength (fc) and modulus of elasticity (Ec) development over time, due to their direct effect on the construction timeline. The effects of concrete curing conditions on material property development are also addressed. Lastly the outcomes and performance of the slabs, namely construction time and slab deformations, are presented.