Bottom Plate Slope Effects on Aerodynamic Behaviour of Hexagonal Cross-Section Bridge Deck

摘要

Long span bridges exhibit various aeroelastic phenomena. The shape of the deck plays an important role to govern the aerodynamic stability against these aeroelastic phenomena. A pentagonal shaped bridge deck has an improved aerodynamic behavior and thus, this has been applied for a number of practical bridges. The advantage of using this type of deck is that this doesn't require additional devices like fairings. Flow on the top deck is controlled by placing a curb on the top deck each side, which is known as Separation Interference Method (SIM), where flow on the bottom deck is controlled by the bottom plate web slope. In the previous researches, detailed investigations have already been carried out on this kind of deck shape, which show their efficiency against aerodynamic instability of the bridge. Recently, a number of constructed bridges have been shaped as hexagon deck instead of pentagon deck. However, the aerodynamic behavior of the hexagonal shaped bridge decks is not well known. In the current study, we carried out a detailed numerical investigation on the bottom plate web slope effect on flow behavior of a hexagonal bridge deck and the results were compared with a pentagonal bridge deck case. Along with the bottom plate web slope, the width of the bottom horizontal flange plate and the side ratio were also altered to observe their influence on the aerodynamic behavior. A two-dimensional finite volume code with RANS turbulence model is utilized in the present study.The result revealed that the optimum bottom plate web slope shifts to larger slope when the bridge deck is shaped as hexagon instead of pentagon.