Study On Ultra-high Performance Concrete Layer Of Lightweight Composite Bridge Deck With Plate Ribs

Prof.Shao proposed a lightweight composite deck system which is composed of a traditional OSD and a thin reinforced Ultra High-Performance Concrete(UHPC)layer using the shear stud connectors to solve two world problems existed in the traditional OSD(Steel structure fatigue crack and pavement damage frequently).This paper is based on the research of the structure of lightweight composite bridge deck with closed ribs and bulb flt ribs.Further more,a new lightweight composite bridge deck with plate ribs which is more convenient in construction,more obvious in force transmission and higher in fatigue resistance is proposed in this paper Then the following work is accomplished for its static and fatigue performance:(1)Based on the construction background of the two bridges of the large span suspension bridge,the paper analyses the fatigue resistance of the lightweight composite deck of plate ribs under the local wheel load,and the results show that the stress amplitude of all fatigue details can meet the fatigue design requirements.The static performance test of plate-rib lightweight composite structure is carried out under positive and negative action,the results show that:plate-rib composite structure scheme(12mm panel + 14mm plate rib)under the action of negative moment load,the crack stress of UHPC is 14.35MPa;Inverted T-shaped rib composite structure Scheme UHPC layer bending tensile crack stress is 24.5MPa;the sliding behavior of the plate-rib lightweight composite structure with two kinds of bolt spacing(150mm and 200mm)under the positive moment load is good,but the pin spacing encryption can remarkably improve the slippage resistance.Overall,the slab-rib lightweight composite deck structure can meet the engineering requirements of the second Bridge of Dongting Lake,but the safety reserve is low and should be used cautiously.(2)Based on the three-span continuous steel-concrete composite beam Zhejiang Huzhou WuYi Bridge,the local finite element model of steel box girder is established,and the fatigue analysis of two kinds of lightweight composite structures of plate rib(16mm plate rib)and U-ribbed stiffener based on nominal stress method is presented,and the results show that:the fatigue resistance of the plate rib and U-rib lightweight composite structure meets the specification requirement,and the safety reserve of U-ribbed composite structure is significantly smaller than that of the slab-rib composite structure in detail 3 and 4.But the safety reserve on detail 5 is larger than that of the plate-rib composite structure;Just increase of panel thickness can not be used as a fundamental solution to the fatigue problems of traditional steel structures,but the use of lightweight composite deck structures can fundamentally and completely solve these problems.(3)The static performance failure tests of the two lightweight composite structures with plate ribs and U-ribbed stiffeners are carried out by the positive and negative moments,the results show that:under the action of negative bending moment,the crack stress of the UHPC layer is 15.8MPa(scheme one,nail spacing 150mm).In plate-rib light combination structure scheme two(nail spacing 200mm),UHPC layer cracking stress is 20.1MPa;U rib light combination structure scheme three(stud spacing 200mm)The cracking stress of UHPC layer is 23.8MPa.Under the action of positive bending moment,the shearing performance of the plate-rib lightweight composite structure with 150mm and 200mm is satisfied with the engineering requirements,but the encryption of the pin spacing can greatly retard the transition of the composite beam to the laminated beam and increase the critical load.(4)The negative bending moment fatigue test of a lightweight composite structure based on Wuyi Bridge is shown that the effect of the UHPC layer over 5 million cyclic loads under the 10MPa bending tensile fatigue stress amplitude is still well,The maximum crack width is only 0.09mm,which shows that the flexural tensile fatigue property of UHPC layer is well;the positive bending moment fatigue test shows that after 500,000 cyclic loads under the effect of 90MPa stress amplitude,no fatigue damage phenomena were found,the interlayer connection was still well,no slip cracks were visible,and the fatigue life of bolt-nailed joints in real bridge was reached 762.93 million times.At the same time,the steel girder stiffened rib webs undergo 500,000 cyclic loads under the effect of 193MPa stress amplitude,the fatigue fracture phenomena are converted according to the design stress amplitude 40MPa at the bottom of the stiffened rib,and the fatigue life of stiffened rib in the real bridge is approximately 56.16 million times to meet the actual engineering requirements.(5)Further more,in order to improve the steel structure of longitudinal rib and cross-beam joints 3 vulnerable fatigue details ③、④ and⑤.This paper select the height of the plate rib,plate thickness,beam thickness and cross-beam flange plate thickness as the parameters fou optimization analysis.The results showed that increasing the height of plate rib could not improve the fatigue details of the above 3 categories,but it had adverse effect on fatigue detail③;Increase the thickness of plate ribs can not improve fatigue details ④and ⑤,but can effectively reduce the fatigue details of ③ stress amplitude;Increase the thickness of crossbeam without improving the stress amplitude of fatigue detail ③,but can reduce the stress amplitude of two fatigue details ④ and ⑤ which is on the crossbeam effectively;For the steel structure deck of high beams(such as box girder),the thickness of the flange plate beneath the beams has little effect on the 3 fatigue details of the above concerns;...