Structural Concrete, Vol. 11, no. 2, June 2010

Written on 19 August 2011.

Concrete in high-rise buildings: practical experiences in Madrid

H. Corres Peiretti, FHECOR Ingenieros Consultores, Spain
M. Gómez Navarro, MC-2, Estudio de Ingeniería, Spain

The use of concrete in high-rise buildings has increased significantly in the last 20 years mainly owing to improvement in all of the technologies associated with this material: admixtures, pumping, transportation and elevation methods, etc. These enhanced possibilities are illustrated by means of four high-rise buildings that were built recently in Madrid, each about 250 m high. The main structural elements of these buildings are presented focusing on the advantages offered by concrete compared to other materials that are commonly used in high-rise construction. The types of concrete considered are high-resistance concrete up to C80, self-compacting concrete, precast and in situ concrete, reinforced or prestressed concrete, as well as normal weight or lightweight concrete. These examples clearly show that, even in structures where the role of self weight is determinant, concrete can be the best solution if all of the different factors involved in the success of a construction site are considered: geometry, ease of construction, means of elevation, prefabrication at factory, repetitiveness, material costs, control requirements, and so on. 

Structural Concrete, Vol. 11, no. 2, June 2010

Written on 19 August 2011.

Flexure-controlled ultimate deformations of members with continuous or lap-spliced bars

D. Biskinis, University of Patras, Greece 
M.N. Fardis, University of Patras, Greece 

A databank of cyclic or monotonic tests to flexure-controlled failure is used to develop/calibrate models for the curvature and the chord rotation of reinforced concrete members at flexure-controlled ultimate conditions - at a 20% post-ultimate strength drop in lateral force resistance - under monotonic or cyclic loading. Models are developed for beams, rectangular columns or walls and members of T-, H-, U- or hollow rectangular section, with or without detailing for earthquake resistance and with continuous longitudinal bars. The models employ simple, explicit expressions for practical application without moment-curvature analysis and are on the safe side for biaxial loading. They are extended to members with longitudinal bars lap-spliced in the plastic hinge region. 

Structural Concrete, Vol. 11, no. 3, September 2010

Written on 19 August 2011.

Anchorage of composite laminates in RC flexural beams

Francesco Micelli, University of Salento-Lecce, Italy 
Andrea Rizzo, University of Salento-Lecce, Italy 
Donatella Galati, University of Salento-Lecce, Italy 

This paper focuses primarily on flexural strengthening with pre-cured fibre-reinforced polymer laminates applied on reinforced-concrete beams with different anchoring devices, both chemically and mechanically applied. The results showed that the ultimate load of the strengthened beams was 35-80% higher than the control beam, depending on the type of strengthening system applied. The lower value corresponds to the beam strengthened using carbon-fibre-reinforced polymer without anchor spikes, the use of which increased the ultimate load by about 14%. The best performance of the strengthening was obtained for the beams strengthened with the hybrid laminates: steel anchors reduced the load drop after the peak, while in the case of the hybrid system and mechanically fastened carbon-fibre-reinforced polymer, the use of the mechanically fastened system resulted in a pseudo-ductile mode of failure. The experimental results were compared with analytical results obtained from the application of recently developed guidelines, published by the Italian Research Council (CNR). 

Structural Concrete, Vol. 11, no. 2, June 2010

Written on 19 August 2011.

Non-linear finite-element modelling of reinforced concrete deep beams

A.H. Alwathaf, Sana'a University, Yemen 

The characteristic behaviour and failure mechanism of a deep beam is investigated using non-linear finite-element analysis in this study. An accurate stress-strain relation is incorporated to describe the stress-strain behaviour of the concrete under compression for uniaxial and also for biaxial stress states. Material non-linearity in the compressive stress field is considered for the concrete in the orthogonal directions and the effect of microcracking confinement and softening on the stress-strain relationship under biaxial stresses are included, employing the equivalent uniaxial strain concept. A computer code FEARCB (finite-element analysis of reinforced concrete beams) is developed to analyse deep beams until failure. The applicability of the proposed finite-element model is investigated by demonstrating the non-linear structural response and failure mechanism of different deep beams and comparing with the available experimental work. Good agreement is achieved between the developed finite-element model and the experimental test results. 

Structural Concrete, Vol. 11, no. 2, June 2010

Written on 19 August 2011.

Concrete gravity-based structures used for offshore LNG storage and regasification in the Adriatic Sea

J. Naess, Aker Solutions AS, Norway
S.I. Giske, Aker Solutions AS, Norway 
L. Bjerkeli, Skanska Norge AS, Norway 

A concrete gravity-based structure, used as an offshore liquid natural gas (LNG) receiving and regasification terminal, has been built and installed in the Adriatic Sea. The design, construction and interfaces of the concrete structure posed many challenges which drew on expertise learnt elsewhere in the world of offshore marine concrete structures. The integration of the LNG tanks and the regasification topsides into a compact concrete structure tested the ability to produce a consistent and easily constructed solution. The resulting structure was simple, efficient, robust, durable and the first of its kind. 

Structural Concrete, Vol. 11, no. 1, March 2010

Written on 19 August 2011.

Unconventional cable-stayed bridges: structural behaviour and design criteria

A.M. Ruiz-Teran, University of East London, UK

Under-deck and combined cable-stayed bridges are two relatively new bridge types that have been developed over the last 30 years. Most of these bridges have been constructed in Germany, Japan, France and Spain, and have been designed by outstanding structural engineers such as Leonhardt, Schlaich, Manterola, Virlogeux and Cremer. The main advantages of these bridge types are: their great structural efficiency; the small amount of materials that they require (allowing economic and sustainable proposals); their great construction possibilities, allowing an increase in the span range of certain construction methods; and their strong aesthetic characteristics owing to the different layouts that can be defined with the stay cables. This paper revises the structural behaviour and design criteria of under-deck and combined cable-stayed bridges, and summarises the main research contributions of the PhD thesis submitted by the author Dr Ana M. Ruiz-Teran, to whom the fib Diploma 2009 for Research (Young Engineers Award) has been recently presented for this work.