Concrete grandstands. Part I: experimental investigation Available to Purchase

Loading–unloading tests were carried out on uncracked (as delivered from the factory) and cracked (after the first loading–unloading cycle was completed) grandstand terrace units. The variation of parameters, such as displacements and strains, with the applied load was recorded and presented in a graphical form. The reduction in stiffness of the units owing to cracks was estimated from these graphs. The predominant mode of failure was found to be cracking initiated at the soffit of the units (tension zone) and mainly around the symmetry line (where maximum bending stresses congregate). These cracks propagated gradually towards the top. The measured and predicted strain distribution across the depth of the vertical part of the terrace unit (riser) was found to be predominantly linear, displaying tension at the bottom and compression at the top. A large portion of the horizontal part of the unit (tread) followed closely the behaviour of the riser, however, to reveal tension rather than compression at the top. This could have some implications for the design of the units. It was concluded that present methods and procedures of evaluating and designing precast concrete terrace units are not integral. Further tests are required, coupled with more analytical work. A Part II companion paper reports on the development of a numeric algorithm describing the analysis process.