Behaviour of prestressed continuous beams

• Autorzy: Lopes S. , Harrop J.
• Języki publikacji: EN

Abstrakty

EN

In previous research works on redistribution of moments, beams have generally been constructed in one piece and transported to the test rigs and then placed on the supports. Great precautions have to be taken when leveling the supports because small deviations from the correct position can introduce large values of unwanted moments corresponding to support settlements. Ideally, at least one support should have a measuring device to measure forces and a threaded device should also be provided to adjust the height of the support as the test progresses. The new technique described in this paper consists of joining two separate precast beams over the supports and maintaining the contact surfaces beams/supports undisturbed even when a top flange is cast in situ. This procedure minimises possible inaccuracies caused transportation and placement of the beams and is closer to the conditions of beams in practice. The paper also describes main results obtained from prestressed composite concrete two-span beams and its implication on codes practice.These codes normally allow an elastic analysis of the structure followed by an adjustment on the diagram of bending moments at the ultimate limit state. In the case of a continuous beam the adjustment is obtained by multiplying the bending moments over the supports by a coefficient, delta, and modifying the whole diagram of bending moments to maintain the static equilibrium of the structure.

Słowa kluczowe

PL

beton zbrojony; beton sprężony; belka sprężona; belka ciągła; prefabrykacja; badanie; projektowanie konstrukcji; redystrybucja momentu

• Wydawca: Komitet Inżynierii Lądowej i Wodnej PAN ; Politechnika Warszawska, Wydział Inżynierii Lądowej
• Czasopismo: Archives of Civil Engineering
• Rocznik: 1998
• Tom: Vol. 44, nr 1
• Strony: 89--105
• Opis fizyczny: Bibliogr. 9 poz., il., tab.

Twórcy

autor

Lopes S.

• Department of Civil Engineering, University of Coimbra, Portugal

autor

Harrop J.

• University of Leeds, England

Bibliografia

• 1. M.Z. COHN, Continuity in prestressed concrete partial prestressing, Partial Prestressing, from Theory to Practice, Vol. I, Survey Reports, NATO ASI Series, Martinus Nijhoff Publishers, pp. 189-256, Boston 1986.
• 2. British Standards Institution, BS8110: Structural use of concrete: code of practice for design and construction, 1985.
• 3. CEN, "Eurocode 2 - Design of concrete structures - Part 1 General rules and rules for buildings", CEN, European Committee for Standardization, ENV 1992-1-1:1991 E, 1991.
• 4. Comité Euro-International du Béton, "CEB-FIP Model Code - 1990", Design Code, Thomas Telford, London 1993.
• 5. S.M.R. LOPES, Moment redistribution in partially prestressed composite concrete beams, Ph. D. Thesis, The University of Leeds, Leeds 1990.
• 6. A. MOUCESSIAN, Nonlinearity and continuity in prestressed concrete beams, Ph. D. Thesis, Queen's University at Kinston, Canada 1986.
• 7. British Standard Institution, BS 1881: Testing Concrete, 1983.
• 8. S.M.R. LOPES, J. HARROP, A.E. GAMBLE, Study of moment redistribution in prestressed concrete beams, Journal of Structural Engineering, A.S.C.E., 123, 5, 561-566, 1997.
• 9. E.W. BENNETT, N. COOKE, L.P. NAUGHTON, Deformation of continuous prestressed concrete beams and its effect on the ultimate load, Proceedings of the Institution of Civil Engineers, 37, 57- 74, May 1967.