Experimental behaviour of RC beams shear strengthened with NSM CFRP laminates

The near-surface mounted (NSM) is one of the most recent techniques applied for the increase of the shear resistance of reinforced concrete (RC) beams. This technique involves the installation of carbon fibre reinforcement polymers (CFRP) laminates into thin slits open on the concrete cover of the elements to strengthen. The effectiveness of this technique for the shear strengthening of T crosssection RC beams was assessed by experimental research. For this purpose, three inclinations of laminates were tested (45º, 60º and 90º) and, for each inclination, three percentages of CFRP were applied in RC beams with a percentage of steel stirrups of 0.10% (qsw). The highest percentage of laminates was designed to provide a maximum load similar to the reference RC beam, which was reinforced with a reinforcement ratio of steel stirrups of 0.28% (qsw = 0.28%). For each percentage of laminates, a homologous RC beam strengthened with unidirectional U-shaped CFRP wet lay-up sheets (discrete strips) applied according to the externally bonded reinforcement technique was also tested, with the purpose of comparing the effectiveness of these two CFRP-strengthening techniques. To evaluate the influence of the percentage of steel stirrups in the effectiveness of the NSM technique, some of the abovementioned CFRP configurations were also applied in beams with qsw = 0.17%The authors wish to acknowledge the support provided by the 'Empreiteiros Casais', Degussa, S&P (R) and Secil (Unibetao, Braga). The study reported in this paper forms a part of the research program supported by FCT, PTDC/ECM/73099/2006

Decision Making for Inconsistent Expert Judgments Using Negative Probabilities

In this paper we provide a simple random-variable example of inconsistent information, and analyze it using three different approaches: Bayesian, quantum-like, and negative probabilities. We then show that, at least for this particular example, both the Bayesian and the quantum-like approaches have less normative power than the negative probabilities one.Comment: 14 pages, revised version to appear in the Proceedings of the QI2013 (Quantum Interactions) conferenc

Timber arch bridges with V-shaped hangers

Thearch is a very efficient load bearing structure, especially when itsshape is affine to the funicular of forces. However, if live loads are predominant as compared to permanent uniformly distributed gravity loads,the arch will be subjected to substantial bending moments, thus losing a great part of its structural efficiency. In traditional arch bridges with hangers arranged in a vertical manner, asymmetrical loads would cause a substantialdeviation of the pressure line from the axial line of the arch.In this paper,an innovative concept for timber arch bridges is introduced where V-shaped hangers, rather than vertical hangers, are used. The adoption of V-shapedhangers significantly contributesto the reduction of the eccentricity between the pressure line and the axial line of the arch, thus decreasing the magnitude of bending moments in the arch.The paper discussesthe advantages of using V-shaped hangers as an alternativetovertical hangers, both in terms ofstatics, in-plane stabilityand dynamic efficiency. Moreover, the design and the recent construction of a parabolic three-hinged archmade of timber, with a steel V-shaped hangeris thoroughly discussedin the pape

Contractual design and public-private parternships for hospitals

Recently the Portuguese Government announced the launching of public private partnerships to build hospitals with the distinctive feature that both infrastructure construction and the clinical activities management will be awarded to a private party. Accordingly there appear coordination issues that are novel in the design of PPP contracts. We explore the conditions allowing for the optimal design contracts design under several some plausible scenarios

On insurance and the cost-sharing of pharmaceutical R&D

Ramsey pricing has been proposed in the pharmaceutical industry as a principle to price discriminate among markets while allowing to recover the (fixed) R&D cost. However, such analyses neglect the presence of insurance or the fund raising costs for drug reimbursement. By incorporating these new elements, we aim at providing some building blocks towards an economic theory merging Ramsey pricing, equity concerns by governments and the strategic incentives, as governments also determine the reimbursement level in countries with a NHS-like system. This will have important implications to the application of Ramsey pricing principles to pharmaceutical products across countries

Selecting negotiation processes with health care providers

We address the question of how a third-party payer (e.g. an insurer) decides what providers to contract with. Two different mechanisms are studied and their properties compared. A first mechanism consists in the thirdparty payer setting up a bargaining procedure with both providers. The second mechanism is the so-called "any willing provider" where the third-party payer announces a contract and every provider freely decides to sign it or not. The main finding is that the decision of the third-party payer depends on the surplus to be shared. When it is relatively high the third-party payer prefers the any willing provider system. When, on the contrary, the surplus is relatively low, the third-party payer will select a negotiated solution

Time-dependent fibre pull-out behaviour in self-compacting concrete

In the present study, the effectiveness of a fibre as an element for transferring stresses across cracks under a sustained load was assessed. Single fibre pull-out creep tests were performed, in which fibre slip was monitored as a function of the time. The influence of the fibre orientation angle (0, 30 and 60 degrees), as well as pre-imposed fibre slip levels, spr, 0.3 and 0.5 mm on the creep response was investigated. Additionally, instantaneous fibre pull-out tests were carried out on undamaged-bond specimens in order to quantify the effects of the pull-out creep behaviour. The damage introduced by the pre-slip levels in the bond of the fibre/matrix interface influenced the long-term fibre pull-out behaviour and, consequently, accelerated the creep rate. However, the assembled pull-out creep behaviour did not differ considerably from the instantaneous pull-out behaviour for the adopted pre-imposed fibre slip levels.This work is supported by the FEDER funds through the Operational Program for Competitiveness Factors - COMPETE and National Funds through FCT - Portuguese Foundation for Science and Technology under the project 18 SlabSys-HFRC-PTDC/ECM/120394/2010. The authors would like to acknowledge the materials supplied by Radmix and Maccaferri (fibres), SECIL (cement), SIKA and BASF (superplasticizers), Omya Comital (limestone filler), and Pegop (Fly ash).info:eu-repo/semantics/publishedVersio

Modelling the influence of age of steel fibre reinforced self-compacting concrete on its compressive behaviour

Steel fibre reinforced self-compacting concrete (SFRSCC) can combine the benefits of self-consolidating concrete technology with those derived from adding steel fibres to quasi-brittle cement based materials. In a recent applied research project joining pre-casting industry, private and public research institutions, a method was developed to design cost-competitive SFRSCC of rheological and mechanical properties required for the prefabrication of SFRSCC fac¸ade panels. To assure safe demoulding process of the panels, the influence of the concrete age on the compression behaviour of the SFRSCC should be known. For this purpose, series of tests with specimens of 12 h to 28 days were tested in order to analyze the age influence on the compressive strength, strain at peak stress, Young’s modulus, and compressive volumetric fracture energy. The experimental program was divided in two groups of test series, one with SFRSCC of a volumetric fibre percentage of 0.38% and the other with 0.57%. To apply the obtained data in the design and numerical analysis framework, the influence of the age on these SFRSCC properties was modelled. This work describes the carried out experimental program, presents and analyzes the obtained results, and provides the derived analytical expressions

Flexural strengthening of RC continuous slab strips using NSM CFRP laminates

To assess the effectiveness of the near surface mounted (NSM) technique, in terms of load carrying and moment redistribution capacities, for the flexural strengthening of continuous reinforced concrete (RC) slabs, an experimental program was carried out. The experimental program is composed of three series of three slab strips of two equal span length, in order to verify the possibility of increasing the negative (at the intermediate support region) resisting bending moment in 25% and 50% and maintaining moment redistribution levels of 15%, 30% and 45%. Though the flexural resistance of the NSM strengthened sections has exceeded the target values, the moment redistribution was relatively low, and the increase of the load carrying capacity of the strengthened slabs did not exceed 25%. This experimental program is analyzed to highlight the possibilities of NSM technique for statically indeterminate RC slabs in terms of flexural strengthening effectiveness, moment redistribution and ductility performance. Using a FEM-based computer program, which predictive performance was appraised using the obtained experimental results, a high effective NSM flexural strengthening strategy is proposed, capable of enhancing the slab’s load carrying capacity and maintaining high levels of ductility.The study reported in this paper forms a part of the research program "CUTINEMO - Carbon fiber laminates applied according to the near surface mounted technique to increase the flexural resistance to negative moments of continuous reinforced concrete structures" supported by FCT, PTDC/ECM/73099/2006. The authors wish to acknowledge the support also provided by the S&P, Casais and Artecanter Companies. The first Author acknowledges the financial support of National Council for Scientific and Technological Development (CNPq) - Brazil, Ph.D. Grant no. 200953/2007-9. The second Author wishes to acknowledge the support provided by FCT, by means of the SFRH/BSAB/818/2008 and SFRH/BSAB/913/2009 sabbatical grants