Weyl-Cartan-Weitzenb\"{o}ck gravity as a generalization of teleparallel gravity

We consider a gravitational model in a Weyl-Cartan space-time, in which the Weitzenb\"{o}ck condition of the vanishing of the sum of the curvature and torsion scalar is also imposed. Moreover, a kinetic term for the torsion is also included in the gravitational action. The field equations of the model are obtained from a Hilbert-Einstein type variational principle, and they lead to a complete description of the gravitational field in terms of two fields, the Weyl vector and the torsion, respectively, defined in a curved background. The cosmological applications of the model are investigated for a particular choice of the free parameters in which the torsion vector is proportional to the Weyl vector. Depending on the numerical values of the parameters of the cosmological model, a large variety of dynamic evolutions can be obtained, ranging from inflationary/accelerated expansions to non-inflationary behaviors. In particular we show that a de Sitter type late time evolution can be naturally obtained from the field equations of the model. Therefore the present model leads to the possibility of a purely geometrical description of the dark energy, in which the late time acceleration of the Universe is determined by the intrinsic geometry of the space-time.Comment: 15 pages, 5 figures; title changed, major modifications; accepted for publication in JCA

A new design model for adhesive joints used to bond FRP laminates to steel beams

The strengthening and repair of existing structures using bonded carbon fiber reinforced polymer, CFRP, laminates has attracted a great deal of attention in the past two decades. Investigations clearly indicate the great potential of this method for restoring the capacity of corroded steel beams and improving their fatigue life. One important issue regarding the use of this technique in strengthening steel structures is the design of adhesive joints used to bond FRP laminates to steel substrates. Very limited research work has been conducted in this area and, at the present time, there is a lack of suitable design models for FRP-strengthened steel members. This paper is mainly concerned with a proposal for and verification of a new design model for adhesive joints used to bond FRP laminates to steel beams for strengthening and repair purposes. Quasi-static tests were performed on steel plate and full-scale beam specimens bonded with CFRP laminates to evaluate the new design model proposed in this study. The failure, in all specimens, took place at the steel-adhesive interface. The new design model presented in this paper was found to be accurate in terms of predicting the ultimate load and failure mode of the joints

Falcon – A Multi-Disciplinary Effort to Promote FRP bridges in Sweden

Sweden has a long history in using fiber reinforced polymer (FRP) composites in marine, transportation and energy sectors. However, when it comes to application of composite materials to build bridge structures, it somewhat falls behind. Despite several advantages that FRP composites offer, such as high specific strength and stiffness, corrosion resistance and light-weight, their infrastructural applications in Sweden have not been fully understood and yet to be realized. The first efforts to use FRP composites for construction of pedestrian bridges started in 2011, however, due to lack of knowledge about the materials and design of composite structures among engineers, they were halted.\ua0 Falcon, a joint effort project with total budget of 640 k Euro funded by VINNOVA and co-funded by industrial consortium partners, aims at gathering together the relevant parties, consisting universities, research institutes, bridge designers, composite manufacturers and clients to realize the first FRP bridge in Sweden.\ua0 The main objectives of the project are to investigate and implement the best practice for FRP bridges and improve the procurement processes for bridge owners and thereby pave the way towards widespread infrastructural application of composites. This paper, presents some results of this project including legal hindrances and possible strategies to promote FRP as a construction material for future bridges

Bridge decks of fibre reinforced polymer (FRP): A sustainable solution

Fibre reinforced polymer (FRP) bridge decks have become an interesting alternative and they have attracted increasing attention for applications in the refurbishment of existing bridges and the construction of new bridges. The benefits brought by lightweight, high-strength FRP materials to these applications are well recognised. However, the sustainability of bridge concepts incorporating FRP decks still needs to be demonstrated and verified. The aim of this paper is to bridge this knowledge gap by examining the sustainability of these FRP solutions in comparison with traditional bridge concepts. An existing composite (steel–concrete) bridge with a concrete deck that had deteriorated was selected for this purpose. Two scenarios are studied and analysed; the total replacement of the entire bridge superstructure and the replacement of the concrete deck with a new deck made of GFRP. The analyses prove that FRP decks contribute to potential cost savings over the life cycle of bridges and a reduced environmental impact