Static and dynamic responses of simply supported and continuous skew composite bridges.

The load distribution factor concept allows the design engineer to consider the longitudinal and transverse effects of wheel loads as two separate phenomena and thus simplifying the analysis and design of the bridge. North American codes of practice do not provide the design engineer with sufficient guidance regarding elastic load distribution factors for skew composite bridges. These codes of practice also require a check to be made on the strength of the sections of the bridge at the ultimate limit state, but they specify the use of elastic load distribution factors for the evaluation of the design forces at the ultimate limit state. Such specifications could lead to an extremely conservative design in some cases and to unsafe design in other cases, since these factors do not represent the actual behaviour of the bridge at that state. Under a moving truck, the bridge exhibits forces which are significantly greater than those under a static truck load. The Ontario Highway Bridge Design Code specifies the dynamic load allowance as a factor of the first flexural frequency of the bridge based on the beam theory. This latter theory is reliable in the case of right bridges without transverse diaphragms. However, in the case of skew bridges or bridges with transverse diaphragms the use of the beam theory leads to substantial errors in the determination of the first flexural frequency and hence the dynamic load allowance. In this dissertation, the predictions of the elastic and the ultimate behaviours of single span simply supported and continuous two-span skew composite steel-concrete bridges are presented. The dynamic response of such bridges is also investigated. A finite element analytical model based on the ABAQUS program, is used for the analyses. The analytical model was verified and substantiated by results from tests on six single span simply supported and three continuous skew composite steel-concrete bridge models. The finite element model is employed to conduct six extensive parametric studies on prototype skew composite bridges, including more than 2500 bridge cases. A statistical package for best fit is used to generate empirical formulas for the following: (i) elastic shear and moment distribution factors for simply supported and continuous skew composite bridges; (ii) ultimate span and support moment distribution factors for continuous skew composite bridges; and, (iii) first flexural frequency of such bridges. The following design parameters were considered when appropriate: angle of skew; bridge aspect ratio; girder spacing; number of lanes; number of girders; the effect of transverse intermediate diaphragms; longitudinal and transverse flexural rigidities; longitudinal and transverse ultimate moments of resistance of the bridge sections; eccentric and concentric truck loading cases; effect of dead load; and, the span ratio. From the results of this design oriented dissertation, the engineer would be able to design skew composite bridges more reliably and economically.Dept. of Civil and Environmental Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1995 .E23. Source: Dissertation Abstracts International, Volume: 57-07, Section: B, page: 4570. Adviser: John B. Kennedy. Thesis (Ph.D.)--University of Windsor (Canada), 1995