Experiment and Modelling on Effective Width of Single and Twin I-beam Composite Girders

Abstract

Effective width (beff) has been widely used by designers, and several specifications can be selected. However, insufficient research has been conducted on the beff of single and twin I-beam composite girders. Thus, finite element (FE) models, calibrated by the experiment, were used to study the effects of slab thickness, web position, interaction degree (ID) of shear studs, width-to-span ratio, and their coupling effects on beff. Different loading types and two definitions of beff were elaborated. The FE results were compared with specifications in Eurocode 4 (EC4) and AASHTO LRFD bridge design specifications (AASHTO). The following results were obtained. The modeling agrees with the experiment. The critical steel height-to-slab thickness ratio is around 4. When the ratio deviates from the critical value, beff is reduced with the increase of slab thickness. ID has a slight influence on beff. beff changes within 10% when ID changes within 10%. The maximum beff can be obtained when the web spacing-to-physical width ratio is 1/2. The decrease of web spacing brings a maximum reduction of 14% on beff, whereas increasing web spacing results in a maximum reduction of 70% for twin I-beam. The coupled effect of web position and slab thickness is limited. The maximum difference is 25%. Recommended equations were proposed to evaluate beff for single I-beam and twin I-beam composite girders based on the specifications in EC4 and AASHTO, which can ensure that the negative error is within 10%.