Reseach On Structural Behaviour Of Orthotropic Deck With Open-shaped Ribs Of Steel Truss Bridge

Orthotropic deck is a structure with longitudinal ribs and cross ribs for plate strengthening. The longitudinal rib and cross rib interact and restraint each other as a unit and reacts in the form of compounding. It’s an efficient plat structure with widespread availability in the real life.Because of the lack of steel, steel orthotropic deck was firstly applied as bridge plate in Germany. From then on, orthotropic steel bridge deck has been widely used in great span bridges in American and European countries for its unique characteristics such as light deadweight, high strength, low bridge height, easy produce and conveniently construction. In 1980s, this technique was introduced in China and successively applied in Highway Bridge and Railroad Bridge in China. However, leading to orthotropic deck’s complicated structural style and stress character, bridge deck appearance many fatigue damage problems, and its mechanical property has been observed in engineering and academe society.Setting in the fatigue damage of orthotropic steel bridge deck for Hai Men Bridge in Tianjin, this paper analyses the condition and reason for the Hai Men Bridge’s orthotropic steel bridge deck crack. Mechanical analysis for orthotropic steel bridge decks with open-shaped ribs is carried out on the finite element model of steel truss bridge, and finite element model of orthotropic steel bridge decks with open-shaped ribs. Research has been done to find method for reducing stress concentration at the longitudinal ribs and cross ribs joint. CoMParing with different round-hole radius at the cross ribs joint, different thickness of longitudinal ribs, cross ribs and bridge decks, and orthotropic steel bridge deck stress characters of elastic ratio at different steel deck Pavement.This paper also analysis how short small cracks appearing at maximum stress concentration part of cross ribs gap and cross ribs’curve gap effect the stress concentration at cross rib gaps.Research in this paper proves that increasing round-hole radius at the cross rib gaps is the effective method to reduce stress concentration of orthotropic steel bridge decks with open-shaped ribs and release steel bridge’s fatigue break. There are tensile regions at the round-hole gap on end part of orthotropic steel bridge decks with open-shaped ribs. The largest tensile stress should happen at around 45 degree oblique downward position and 30 degree oblique downward position. Round-hole gap at other regions is pulled on one side and pressed on the other side. The largest tensile stresses also happen at around 45 and 30 degree oblique downward position. The crack of round-hole gap at the end part of cross ribs could reduce stress of the whole bridge deck. Under long period vehicle load circulate recent actions, welding position between steel decks’cross ribs and longitudinal rib flanges first cracks, and then curve gap cracks. Cross position between cross ribs and longitudinal beam of orthotropic steel bridge decks with open-shaped ribs in steel truss bridges most easily appears fatigue crack. Stress concentration at every intersegmental cross following decline first and then increase rule. The research result been studied above match the crack circumstance of Hai Men Bridge.