Modelling and analysis of interface in composite box girder bridges

The role of composite box bridges in the interchanges of modern highway systems has become more and more popular for functional, economic and artistic considerations. This type of structure, guides to an efficient transverse load distribution due to excellent torsional stiffness of the part. Further utilities and services can be readily provided within the boxes. In this thesis as a first approach a study of the effect of shear connector's numbers and distribution on the behaviour of composite box girder bridges is submitted. Additionally, several finite element models are developed to assessed against the results acquired from a field test. A number of factors are considered, and confirmed through available experimental results, especially full shear connections, which are obviously essential in composite box girder. A good representative for shear connectors of suitable finite element type is considered. Preparatory results signalize that number of shear studs can be obviously reduced to facilitate adoption of a new arrangement in design of composite box girder bridges with full makeup. The parametric investigations are performed along with the composite box girder model to appraise the effects of several important parameters on the behaviour of the girder. The outcomes from this study would enable bridge engineers to design composite box girder bridges more reliably and economically. Referable to the complexity of the three-dimensional interaction between shear connector and concrete, there is little success in numerical modelling of the push-out test in literature. A three-dimensional finite element model with multiple elements was counseled to simulate shear connector based on static loading. The interaction between the steel connector and concrete will cause the main significance of the global behaviour of the structural element. The geometry and material nonlinearities of headed stud, steel beam were included in the finite element model. Contact regions between the concrete and steel elements are simulated using surface to surface and embodiment techniques. Shear capacity for studs are obtained and results compared with various codes of practices such as EC4, AISC and BS and BS5950. The proposed model was used to estimate the load-slip curve and to analyse important phenomena of the mechanical behaviour of connectors that are usually difficult to evaluate through tests.