Based on the investigation of vehicle loads, the model of the random dense vehicle load was simulated, and three different degree dense vehicle loads were obtained with the simulated model. The calculated results show that the random dense vehicle loads moving on the bridge structures is very dangerous for the security of the structures; the combination factor 1.4 designed in the code is not precise for the situation of random dense vehicle loads, and it is suitable for the common vehicle loads.
On the basis of truss-and-arch model and the concrete softening strength criterion under ultimate state, a formula for shear capacity of reinforced concrete (RC) beam with diagonal reinforcement was established and verified. Accordingly, six RC beams with diagonal reinforcement and corroded stirrup were tested along with control group, the tested results were analyzed by liner regression to modify the formula given. Hence a formula for inclined section shear capacity of stirrups corroded RC beam with diagonal reinforcement was proposed and compared with a preceding formula without a consideration of diagonal reinforcement in corroded RC beam .The results showed that the existence of diagonal reinforcing steel bars enhanced the behavior of vertical compression web member in truss institutions, therefore increasing the shear force shared by truss mechanism. The inclination of diagonal web member is a crucial parameter of truss model. As the stirrup corrosion aggravating, the shear bearing capacity of such RC beams does not decrease drastically.
Based on the finite strip thought and displacement interpolation function of Bernoulli-Euler beam element, using the transformation relationship between skew coordinate and Cartesian coordinate system, a new kind of thin parallel slab element was established, element stiffness matrix and consistent mass matrix were derived. The vibrating frequency of simply supported skewed slab was calculated. Computing results were compared with theoretical results and Ansys results. The maximum error was 2.68%. Changing the mesh density of skew slab, the convergence of present element was tested. Examples show that this element has the features of high precision and strong convergence. At last, the vibrating frequency coefficients of skew slab bridge with different ratios of span to width were provided, which can be adopted to compute the vehicle’s impact factor of skew slab bridge by specification method.
In constant temperature and humidity environment, the properties of shrinkage and creep for a group of plain concrete and reinforced concrete columns were observed in long-term and experimental method. The curves of concrete shrinkage and creep effect with time were obtained. Checking coefficient and type coefficient of shrinkage and creep effect were put forward in order to predict models of shrinkage and creep. Using the least square method, functions of checking coefficient and type coefficient were acquired and the prediction models of shrinkage strain and creep coefficient of concrete were obtained based on the modification of the formula of JTG D62-2004. The foundation is laid for the application of the long-term performance research in bridge structure.
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