Nozomi Bridge - a hybrid structure of stress-ribbon deck and truss
N. Ogawa, Chubu Regional Bureau, Ministry of Land, Infrastructure and Transport, Japan
Y. Kamiya, Oriental Construction Co., Ltd, Japan
T. Yoshikawa, Oriental Construction Co., Ltd, Japan
G. Yu, Oriental Construction Co., Ltd, Japan
M. Tsunomoto, Oriental Construction Co., Ltd, Japan
It is well known that one drawback for stress-ribbon bridges can be that significant horizontal reactions at the abutment can be generated and that they have low flexural stiffness. The latter prevents them from being used as roadway bridges. A new hybrid structure of stress-ribbon deck and truss has been proposed and was adopted in the construction of Nozomi Bridge in Japan, a roadway bridge opened to traffic in 2003. Static and dynamic behaviours of the hybrid structure have been studied analytically and experimentally. The results show that the hybrid bridge has advantages over the stress-ribbon deck bridge as it generates much less horizontal force in suspension cables and has higher flexural stiffness, suitable for use as a roadway bridge, and that the hybrid bridge has advantages over the truss bridge since it can be constructed without extensive falsework and without large erection equipment. In this paper, at first, the hybrid structure is described, then analytical and test results are used to show its static and dynamic characteristics, and finally the construction of Nozomi Bridge is outlined.
Cracking analysis of reinforced concrete tensioned members
S. Khalfallah, University of Jijel, Algeria
An analytical model, which can simulate the cracking response of reinforced concrete tensioned members, is presented. This model is principally based on the bond stress-slip repartition function that was successfully applied to the analysis of tensile reinforced concrete members. The formalism of repartition functions of loads, strains and slip between steel and surrounding concrete, has allowed analysis of the cracking phenomenon and its influence on the structural behaviour of reinforced concrete members. The tension stiffening effect accompanying the cracking mechanism is taken into account in a more appropriate manner. The phenomenon of localisation of micro-cracking owing to the softening behaviour of concrete in tension is based on the conservative concept of the cracking fracture energy assuming that the band of strain localisation is an intrinsic parameter of the material. The predictive results show that the model is very satisfactory, allowing the evaluation of each material contribution especially in the cracked range. Moreover, a correlation between the obtained and experimental results is observed through the local and global responses.