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This work presents the results of an experimental research program, carried out at the Technical University of Catalonia, to study the debonding behavior of carbon fiber-reinforced polymers (CFRPs) used to strengthen beams in bending. The research is a part of a program that aims to study the strengthening of concrete bridges (both monolithic and segmental) using CFRPs. The overall objective of this paper is to present the results obtained from bond tests performed on material-scale specimens and full-scale tests performed on monolithic and segmental beams. A normalized test is proposed to obtain a more reliable estimate of the debonding strain of CFRPs, which may govern the design of CFRP-strengthened concrete structures. The test is proposed to supplement available design models, as the formula of km included in ACI 440.2R-02 by ACI Committee 440. The results from the tests are checked with the data obtained in large-scale tests, representative of actual bridges. The reported values are significantly lo...

This paper presents an externally prestressed high strength concrete viaduct designed and erected in Spain. This viaduct, a three-span (41 + 50 + 41 m) continuous beam, has been designed and built with a 60-MPa strength concrete and a fully external replaceable prestressing. The paper describes the bridge, the erection procedure, the ultimate analysis performed with a nonlinear finite-element numerical model, and the thermal stresses measured and calculated at the anchorage diaphragms due to the hydration heat of the concrete. The results of the static tests carried out on the bridge also are commented upon.

The concern for occupational health and safety in construction work is reflected in the many preventive measures taken. However, examples of the systematic assessment of project alternatives aimed at minimizing occupational hazards are rare. This paper proposes a measure of occupational safety [occupational risk index (ORI)] that is based solely on the project design and resulting construction process, and is a function of the activities carried out and their specific occupational risk (probability and consequences of occurrence). The ORI can thus be used as an indicator to feed multicriteria decision-analysis tools. The proposal is illustrated with a simple example in which two alternatives (one precast and the other constructed in situ) are prioritized in terms of occupational safety, and certain aspects related to redesign are briefly addressed. With the ORI, occupational safety goes from having a passive influence (application to projects that have already been designed) to an active one (influence on the design concept itself) in the design stage of construction projects. The research is based on an analysis of the applicable legislation and interviews with experts.

A numerical model for the ultimate analysis of externally prestressed concrete bridges has been developed. The proposed model can analyze simply supported or continuous, monolithic or segmental bridges, with external unbonded prestressing and/or internal bonded prestressing. The model evaluates the behavior up to failure of this type of structures, calculating displacements, rotations, joint opening for segmental bridges, internal forces, and prestressing steel stresses at each load increment. Some codes recommend values or approximate formulas for the increase of stress of the prestressing steel at ultimate. These values are sometimes too conservative or unreasonably high. The proposed model includes reinforced concrete, prestressing tendons, and joint finite elements. These elements are described in this paper. A comparison between the numerical model and available test results is also provided, showing excellent correlation.