Lecture

Prestressed Concrete: Principles and Types

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In course

CIVIL-430: Concrete bridges

Ce cours traite les principaux aspects de la conception et du dimensionnement des ponts en béton armé et précontraint. L'accent est mis sur les ponts poutres. Etude des aspects suivants : optimisation du comportement structural, dimensionnement, dynamique ...

Description

This lecture covers the principles and types of prestressed concrete, including pre-tension and post-tension methods, interior and exterior prestressing, different types of prestressing, and the effects of prestressing on reinforced concrete. It also discusses the initial prestressing force, deformations, and the system composed by reinforced concrete and cables. The lecture further explores the forces between cables and reinforced concrete, losses of prestressing due to friction, and the interaction between relaxation, shrinkage, and creep effects. Examples of beams with eccentric cables are also presented.

Instructor

Aurelio Muttoni

Aurelio Muttoni is full Professor and Head of the Structural Concrete Laboratory at the Ecole Polytechnique Fédérale de Lausanne (Switzerland). He received his diploma and PhD in civil engineering from the Swiss Federal Institute of Technology, Zurich, Switzerland, in 1982 and 1989, respectively. His current teaching activities focus on the conceptual design of structures, theory and dimensioning of concrete structures as well as bridge design. His research group is active in the following domains: behaviour and design methods for structural concrete, conceptual design of innovative structures, shear in structural concrete, punching shear of slabs, nonlinear structural analysis including its reliability, bond between steel and concrete, aggregate interlocking, fatigue and influence of sustained loading on the concrete strength, mechanical behaviour and design concepts for ultra-high performance concrete, textile concrete and recycled concrete. Aurelio Muttoni was the recipient of the Chester Paul Siess Award for Excellence in Structural Research in 2010 and the co-recipient of the Wason Medal for Most Meritorious Paper in 2014 of the American Concrete Institute. He is a member of the Presidium of fib (International Federation for Structural Concrete), several fib commissions and task groups and has been Project Team Leader for the second generation of EN 1992-1-1 (Eurocode for structural concrete). Aurelio Muttoni is also cofounder and partner of the Muttoni & Fernández consulting office (www.mfic.ch). This office is active in the conceptual design, analysis and dimensioning of load-bearing structure in architecture and civil engineering constructions as well as consulting activities in the field of structural engineering.

Official source

Related concepts (23)

Prestressed concrete

Prestressed concrete is a form of concrete used in construction. It is substantially "prestressed" (compressed) during production, in a manner that strengthens it against tensile forces which will exist when in service. This compression is produced by the tensioning of high-strength "tendons" located within or adjacent to the concrete and is done to improve the performance of the concrete in service. Tendons may consist of single wires, multi-wire strands or threaded bars that are most commonly made from high-tensile steels, carbon fiber or aramid fiber.

Precast concrete

Precast concrete is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment, transported to the construction site and maneuvered into place; examples include precast beams, and wall panels for tilt up construction. In contrast, cast-in-place concrete is poured into site-specific forms and cured on site. Recently lightweight expanded polystyrene foam is being used as the cores of precast wall panels, saving weight and increasing thermal insulation.

Reinforced concrete

Reinforced concrete, also called ferroconcrete, is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ductility. The reinforcement is usually, though not necessarily, steel bars (rebar) and is usually embedded passively in the concrete before the concrete sets. However, post-tensioning is also employed as a technique to reinforce the concrete. In terms of volume used annually, it is one of the most common engineering materials.

Concrete

Concrete is a composite material composed of aggregate bonded together with a fluid cement that cures over time. Concrete is the second-most-used substance in the world after water, and is the most widely used building material. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminium combined. When aggregate is mixed with dry Portland cement and water, the mixture forms a fluid slurry that is easily poured and molded into shape.

Types of concrete

Concrete is produced in a variety of compositions, finishes and performance characteristics to meet a wide range of needs. Modern concrete mix designs can be complex. The choice of a concrete mix depends on the need of the project both in terms of strength and appearance and in relation to local legislation and building codes. The design begins by determining the requirements of the concrete. These requirements take into consideration the weather conditions that the concrete will be exposed to in service, and the required design strength.

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