Serviceability Limit State Aspects of Continuous Bridges Using Precast Concrete Beams

Within a land area of about 11OOkm², the population of Hong Kong has increased to more than 6M. Land is scarce and land prices are high; consequentially the vast majority of the population is accommodated in multistorey buildings. Most of these were completed at high speed under the pressure of strong demand and subsequently exposed to severe atmospheric attack. The problems of these buildings can be discussed under separate headings, i.e. public housing, constructed by Government funds, and those provided by the private sector. J.K.W. Chan and D.A. Morris

Twenty high strength concrete deep beams with various top-to-bottom loading ratios were tested to failure. Two types of web reinforcement were investigated: type ‘a’ web pattern with verticul web reinforcement ratio pv at 0.48% and type ‘b’ web pattern with pv at 1.43%. Detailing of the web reinforcement followed the recommendations given by the UK CIRIA Guide, which would seem to be the only design document for deep beams subjected to combined top-and-bottom loading. It is found that the CIRIA detailing rules help to ensure ductility in the behaviour of the specimens, and this in turn yields consistent ultimate shear strengths irrespective of the loading condition imposed on the beams. Comparisons with test results also show that the CIRIA predictions are both conservative and consistent. K.H. Tan, Professor F.K. Kong and L.W. Weng