Applied Mechanics and Materials Vols. 405-408

Abstract: Simply supported beam by applying the external prestressing change as a continuous system can be a substantial increase in the bridge carrying capacity, but more complex in vitro beam connection segment force. To study the forced state of external prestressing connection mode of the simply-supported and continued structure system, it is studied by both the way of numerical simulation using the finite element analysis software ANSYS and experimental research. The physical model to simulate the prestressed concrete structure and the test process are described. By comparing the results of numerical simulation and experimental research, the stress stage of the connection mode is divided. As a result, a simplified method of calculating the deflection based on the elastic theory is proposed. The internal force redistribution of the structure is also determined. The results of the numerical simulation method are reliable because it is similar to measured results.

Abstract: The design of the shock transmission unit (STU) was based on the maximum displacement, nominal load, lock up velocity and other parameters. The STU was subjected to a series of tests for checking its behavior. During the slow movement test, the resistance force is 10kN; during the simulated dynamic test, the deflection between the point of zero load and the point of maximum load is 4mm, and the deflection during the sustained load portion of the test is 5mm; during the fast movement test, the STU locked up within 1mm, the deflection from the point of lock-up to the maximum test load is 5mm, and the stiffness of STU throughout the force range from lock-up to maximum test load in tension and compression is 7.72% and 3.6% respectively. During the overload test and the fatigue load test, the STU shows no sign of leakage or binding.

Abstract: The distance between barriers of lower deck and bridge piers of upper deck is small in Luotang River Double-Deck Viaduct. And so impact accidents with barriers of lower deck will result in vehicle frontal impact with bridge piers of upper deck, which will cause serious consequences for the main structure of bridge. So it is necessary to design a special barrier for bridge pier protecting. A kind of composite barrier is put forward considering safety performance, landscape, economic and other factors. This barrier adopted impact resistant steel as upper part and reinforced concrete wall as lower part. The barrier safety performance was evaluated by means of computer simulation with simulation models checked through full-scale impact tests results. The analysis results indicate that this barrier can protect bus with impact energy of 520kJ, unit truck with 650kJ and tractor-trailer truck with 894kJ, far higher than the highest impact energy 520kJ in current standards, and the entire performance index can meet standard requirements. It can be sure that during the impact process the deformed barrier and incline-out vehicles cannot collide with bridge piers of upper deck.

Abstract: Focused on the problems of prefabricated prestressed concrete small box beams cambering at mid-span, FEM theory and orthogonal test method are applied to analyze the sensitivity of factors involving elastic modulus of concrete (E), effective prestressed force (P), environmental relative humidity (RH), beam-preserving time (T) etc, and approximate expressions for calculating camber of the prestressed concrete small box beam are obtained by stepwise regression method. The fitting precision can meet the requirements of the engineering design, and the study method can provide reference for prediction and control of main beam camber.

Abstract: A comparative study was carried out by establishing an overall bridge spatial finite element model and a transverse frame model on transverse structural characteristics of Kunyang Bridge on Wenzhou-Fuzhou Railway line. The longitudinal variation of transverse stress in box-girder shows peaks distribution. The absolute values of transverse stress decrease gradually at peaks and valleys in overall tendency as it’s close to the mid span. The calculation results of the rigid support frame method can envelop the calculation results of the overall bridge spatial finite element model in side span region without suspenders.It verifies the reasonability of the rigid support frame method to calculate transverse stress of this region. And the width of transverse frame should designate one third of suspender spacing or more in transverse stress calculations of central span region with suspenders.

Abstract: By directing at the current situation of excessive midspan deflection in prestressed concrete continuous bridge during the past few years, this paper raised a calculation method to elevate the pre-camber. Factors that affect bridge alignment after the bridge is completed were treated as uniform load, test data about the existing bridge were set as the basis, quartic polynomial function was adopted to fit the pre-camber of bridge under construction, and the following conclusions were gained through simulation analysis on the bridge: 1) During calculation for construction pre-camber, this method can overcome or weaken the situation of excessive midspan deflection when the bridge is at operation stage; 2) It can reduce detail analysis on displacement caused by concrete creep and automobile load after the bridge is completed; 3) Relevant parameters are introduced to calculate predicted value of midspan deflection and make calculation for empirical pre-camber more rigorous; 4) Its feasibility has been verified through calculation to guarantee load carrying safety in bridge construction and operation process, so it has relatively high promotion and application values.

Abstract: The structure of cable-stayed bridge with inclined and arched tower is complex and the force is complicated, especially the pylon, whose design and construction require detailed calculation and analysis. In case of the construction of Datong Nansanhuan Yuhe bridge project, in order to ensure the safety during its construction, the detailed construction plan was planned and the finite element model was established to analyse the dynamic performance of structure during construction of pylon. The result shows that, during the construction of low pylon, each frequency order of bridge structure is reduced to a steady level with the pylon completed gradually, and the low frequency changes moderately.

Abstract: Due to the characteristic of ordinal consistency in the analytical hierarchy process (AHP) difficult to meet, the method combined AHP and the theory of fuzzy mathematics is introduced, the idea of fuzzy analytic hierarchy process is introduced innovatively. The failure mode and the main factor of failure induced during construction of bridge engineering are identified. The method can exert the brain advantage of evaluation, and simplify the computation process.

Abstract: The six types of bilayer paving structures were composed based on the characteristics of the three most common paving materials in the article. And tests of high-temperature stability and low-temperature fracture resistance were done according to the climate conditions of Tianjin City, thus providing technological references for choice of paving material of steel bridge deck in the Chinese 2th climate zone. The testing results show that: the paving structure of 2.5cm SMA above and 2.5cm epoxy asphalt mixture below is optimal in the comprehensive indexes of technology and economy, it's the suggested paving form of steel bridge deck suitable for the Chinese 2th climate zone.

Abstract: This paper introduced a concept of frequency inspection coefficient to find relationship among frequency inspection coefficients of static flexibility, strain and structure dynamic load. Explored this theory resemblance of structure stiffness evaluation which based on frequency inspection coefficient and static flexibility inspection coefficient separately, and verified reliability of this method which aiming at arch bridge via the result of measured static and dynamic test data of sample bridge.