Applied Mechanics and Materials Vols. 204-208

Abstract: The common safety accidents in bridge construction were according to safety rheology and mutation.The paper got the physics model and mathematical model of some common safety accidents that sky diving ,object striking and collapsing by safety rheology and mutation. It can be used to analyse safety accidents in bridge well.

Abstract: Finite element analysis and calculation are held on the superstructure of the auxiliary channel bridge at the right branching of Beijiang Bridge for a short condition and the service phase. The theoretical launching force is calculated and amended in construction. The results show that when considering load effects such as the dead loads of box girders, the live loads of decks and the pre-stressed secondary forces, the eccentric stress state will appear on the webs, and the steel stress produced by shrinkage and creep of concrete can not be ignored. So the launching force must be amended during the construction process. These conclusions have a certain reference value on the bridge design and construction.

Abstract: Fire accidents are dangerous and uncertain. The steel bridges are particularly serious fire threat due to the steel own shortcomings. Steel bridges in the planning, design and operation need a complete set of fire relief measures. For steel bridges, the paper presents fire safety, fire loss distribution function and fire safety design. For a steel bridge, the paper presents specific fire safety measures and rescue processes.

Abstract: With the rapid increase of the bridge span, the bridge structure tends to be more flexibility, thus causes wind-induced vibrations more prominence. Taking Sutong Bridge as an example, numerically identifies the three component coefficients of girder with different angles of attack, comparing to the girder with guide plates and the girder with central slot, it is found that the guide plates has little influence to the three component coefficients of girder and the central slot can obviously increase the wind resistance capacity of girder, provides the wind-resistant basis for girder of large-span bridge design.

Abstract: On the basis of summarizing the hydrological characteristics and shipping characteristics at the location of Chongqing Caiyuanba Yangtze River Bridge, the method of setting anti-collision bridge piers by the risk analysis was determined, and the anti-collision design program of P15 and of P16 side pier was analyzed emphatically. The anti-collision program with intercept cable, thin-walled cofferdam and structural strengthening itself were compared and the advantages, disadvantages and the scope of application of the protective facilities were discussed. Analysis showed that it was very effective to reasonably choose the pier needed to be protected emphatically so as to select protective measures program of the piers with targeted with hydrology, waterway and other information on the location combined with structural analysis. These conclusions have some guidance and reference significances for determining the anti-collision program of side pier in large bridges.

Abstract: The deflection for pre-stressing concrete thin-wall box girders bridges under action of multi-span loads exposed to fire was presented in this paper. Based on thermal and mechanics parameters, the fire and load model was designed, the space analysis procedure was performed to analyze the maximum deflection of each span during prophase and anaphase of extending-fire time, altogether 4 kind of load case. The studied results indicate: under condition of the whole span fire and load model of multi span, the mid-span deflection of the second span is down-warping during the fire prophase which its time is about 20 minutes, and up-warding or horizontal during the fire anaphase which its time is about 50 minutes; the deflection of the first and third span is down-warping with extending time during the whole fire time.

Abstract: W/C ratio and the quantity of fly ash added have obvious influence on creep of high performance concrete. Effect of different quantities of fly ash on creep of high performance concrete of different W/C ratios used in bridge is studied in this research whose results reflect that creep value reduces along with reduction of W/C ratio at a certain quantity of fly ash added. Adding fly ash restrains creep on the whole, however, the degree depends on the quantity of fly ash added. Creep value of high performance concrete mixed with class-I fly ash at blend ratio of 12~40% is lower than that of standard concrete and fly ash at blend ratio of 18% has the best effect. Creep value in 365d is 51% of that of standard concrete at fly ash blend ratio of 18%, while at fly ash blend ratio of 40%, creep value in 365d is lower than that of standard concrete but higher than that of concrete at other blend ratios. It is generally considered that inhibition of creep of high performance concrete begins to fall beyond blend ratio of 30%.

Abstract: Existing initiative anti-collision of bridge system was so complex and high costs, so we analysis of various factors of the collision of the bridge, putting forward the key factors of the initiative anti-collision and simplifying the bridge initiative anti-collision model. Furthermore, in the light of the key factors to designed a set of initiative anti-collision safety system for Xingjiang large bridge as an example. Based on the limit of thoughts and ideas, raise the concept of the voyage level of security, and design the work of software process.

Abstract: The South-to-North Water Division Bridge is a prestressed concrete composite box-girder bridge with corrugated steel webs constructed by cast-in-place cantilever method. Its modal shape and modal frequency were calculated during each cantilever construction stage. And the formula about the relation between length of cantilever and natural frequency was derived.

Abstract: After continuous multi-span rigid-frame bridge is closed up, long-term creep and shrinkage of concrete induce unfavorable effect on deformation and internal forces of main girder and piers. Imposing some horizontal jacking forces at closure stages is the key steps to ensure construction quality. Taking Mayinghe Bridge as study objective, main factors determining the jacking force value are analyzed. The deformation and internal forces at construction stage and operational stage of the bridge are calculated through FE method when different jacking force combination is applied at closure stage. Jacking force combination is chosen that not only improve the deformation and internal forces conditions at operational stage but also ensure the construction safety at the construction stages. The monitoring data show that the simulation has a good agreement with the practical results.