Shear Strengthening of RC Beams with EB FRP: Influencing Factors and Conceptual Debonding Model

This paper deals with the shear strengthening of RC beams using externally bonded (EB) fiber-reinforced polymers (FRP). Current code provisions and design guidelines related to shear strengthening of RC beams with FRP are discussed in this paper. The findings of research studies, including recent work, have been collected and analyzed. The parameters that have the greatest influence on the shear behavior of RC members strengthened with EB FRP and the role of these parameters in current design codes are reviewed. This study reveals that the effect of transverse steel on the shear contribution of FRP is important and yet is not considered by any existing codes or guidelines. Therefore, a new design method is proposed to consider the effect of transverse steel in addition to other influencing factors on the shear contribution of FRP (Vf). Separate design equations are proposed for U-wrap and side-bonded FRP configurations. The accuracy of the proposed equations has been verified by predicting the shear strength of experimentally tested RC beams using data collected from the literature. Finally, comparison with current design guidelines has shown that the proposed model achieves a better correlation with experimental results than current design guidelines.     

Quantitative Characterization of Mechanical Stress Field and Fracture Strength in Isotropic Brittle Materials During Crack Tip Propagation

A generalized method for characterizing mechanical stresses in brittle materials during crack tip propagation is presented. This approach was derived from classical fracture mechanics and is therefore mechanism independent and applies to any isotropic brittle material, including glasses, fine grained ceramics or metals, and high stiffness polymers. A practical implementation demonstrates the merits of this technique: the fracture strength can be determined by characterizing the angle between the free surface of a flexural overload fracture and stress intensity factor loci. The accuracy of this method was phenomenologically validated using flexural strength tests on glass as a model material system. In addition, such fractographic measurements can also be used to characterize an inhomogeneous internal stress field, and thereby, for example, help discriminate whether the sample failed due to pure bending loads alone, or whether membrane stresses were also present.     

Understanding the impact of BIM on collaboration: a Canadian case study

ABSTRACT

Facilitating collaboration amongst project stakeholders in the construction industry is one of the central tenants of building information modelling (BIM). While there is increasing evidence of the positive influence of BIM on project outcomes, ambiguity remains around BIM’s true impact on collaboration. The presented case study aims to develop insights into the impact of BIM on collaboration in the architecture, engineering and construction industry. A critical realist perspective was adopted and a systematic combining approach was employed to support data collection and analysis. Data were collected through a longitudinal case study of a large design–build project in Canada. The unit of analysis was the individual project team member. Five cognitive determinants identified from the analysis are seen to inform an individual’s framing of event patterns in the context of BIM-enabled collaboration: requirements, expectations, intentions, incentives and capabilities. From this perspective, the impact of BIM on collaboration is understood as a reshaping of an individual’s cognitive determinants, which influence a team member’s framing of event patterns enacted throughout project delivery. This shift is manifested by changing information landscapes, i.e. sources and flows of information, that are generated, shared and consumed within the project team.