Research On Spatial And Full-range Mechanical Properties Of Steel-UHPC Light-weighted Composite Bridge Deck

To solve the two types of disease in the convent io na l orthotrop ic steel deck, which are dama ges in aspha lt sur facing and fat igue cracking in orthotropic steel decks, Professor SHAO Xudong has proposed of an innovat ive composite bridge deck system that consists of an orthotropic steel deck and a thin re inforced U ltra- high perfor mance concrete(UHPC) layer. The resultant O SD- UHPC compos ite deck is referred to as a stee l- UHPC light weight compos ite deck(LWC D) system, w hich can effect ive ly reduce the fat igue stress a mplitude of stee l str ucture, and can a lmost avo id the occurrence of paveme nt damage.This research is conducted in two aspects, inc lud ing the mechanica l properties in both vert ically and hor izo nta lly and in the full- range test of the steel- UHPC lightwe ight composite deck:(1) In order to get the mecha nical propert ies of the steel- UHPC lightwe ight compos ite deck, a local finite ele ment model has been built based on t he Second Dongt ing Lake Bridge, the results indicated that the mecha nical properties both vert ically and hor izonta lly of t he steel- UHPC lightwe ight co mposite deck showed obvious locality under w hell loads. The lateral stress of each ana lys is section a ll appear stress peaks at the latera l posit io n where whee l loads locat ion, while in other regio ns, the lateral stress of each sectio n for ana lys is see ms a lmost the sa me. The maximum transverse tensile stress of UHPC la yer is 6.76 MPa. In the ana lys is section which d irectly bears the load, the longit udina l stress appears stress peaks at the lateral posit io n where wheel loads location. While in other analys is sect ions, the longit udina l stress distr ibuted evenly. The maximum longit udina l tens ile stress of UHPC layer is 7.2MPa.(2) To exp loring the composit ion of t he second and third structura l syste m stress in the composite br idge deck, static loading test and finite e le ment model were used on a full- scale model. The results ind icated that the transversal stress of the composite deck under vehic le load is obvio us ly confined to an area. The third structura l syste m stress is the primary stress of the composite deck in t his area, its unit- wide section bend ing mo ment reached 75% of the tota l mome nt. The proportion o f t he third structura l syste m stress decreased rapid ly out of t his region, and the second structura l system stress became the major force.(3) Full- range test and numer ica l ana lys is were conducted on this full- scale model, t he results showed that t he transversa l cracking stra in o f t he UHPC layer during the test reached 1798με. According to the crack ing load measured, the transversal cracking stre ngt h atta ined 35.3MPa by us ing e lastic ana lys is method, which is much higher than t he maximum tra nsversa l stress of UHPC la yer under designed vehic le loads. The load- disp lacement curve cont inues to rise after cracking, the reinforced UHPC la yer exhib it good tens ile toughness. With t he load increasing, the crack w idth of the mode l did not change much, but the number of cracks and crack lengt h gradua lly increased, the steel- UHPC lightwe ight composite deck has a good diss ipation capacit y of ener gy. Whe n loaded to the peak va lue, the w idest crack is only 0.07 mm w ide, which suggested that the tensile fa ilure seems not to occur in the UHPC layer dur ing us ing period.