Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
The simultaneous use of piles and prestressed anchors in foundation design
Many structures in civil engineering impose important tension loads to the foundations. In such cases prestressed anchors are sometimes used. In some cases previous foundation elements may exist, as in underpinning works. Moreover, foundations in difficult or special subsoil conditions may have to support alternating compression/tension loads, in addition to high overturning moments, thus requiring the use of prestressed anchors for the tension loads, and piles for the compression loads. A more rigorous 3-D interaction of the structure with soil, piles, and anchors can be achieved mostly with aid of modern numerical techniques, which may be too complex and time consuming for practical purposes. Therefore, the evaluation of the loads from the structure to the foundation elements is performed in common design practice using mainly oversimplified and conservative procedures, with no account of the actual stiffness of the different foundation elements. The paper presents a simplified design procedure to evaluate the loads in piles and prestressed anchors when simultaneously used in foundations under tension loads and high overturning moments. Although involving some necessary simplifications for the sake of design, the procedure keeps the main features of load transfer trom piles and anchors to the surrounding soil. The approximate method has been adopted by the authors in relevant projects in Brazil, whose long term satisfactory performance indicates its appropriate performance. Two practical examples have been selected to illustrate the application of the proposed method. It is shown that anchor prestressing plays an important role in limiting tension loads on the piles and controlling foundation eccentricity. The importance of monitoring for replacement of occasional prestress losses to prevent long-term pile overstressing is illustrated.
The simultaneous use of piles and prestressed anchors in foundation design
Many structures in civil engineering impose important tension loads to the foundations. In such cases prestressed anchors are sometimes used. In some cases previous foundation elements may exist, as in underpinning works. Moreover, foundations in difficult or special subsoil conditions may have to support alternating compression/tension loads, in addition to high overturning moments, thus requiring the use of prestressed anchors for the tension loads, and piles for the compression loads. A more rigorous 3-D interaction of the structure with soil, piles, and anchors can be achieved mostly with aid of modern numerical techniques, which may be too complex and time consuming for practical purposes. Therefore, the evaluation of the loads from the structure to the foundation elements is performed in common design practice using mainly oversimplified and conservative procedures, with no account of the actual stiffness of the different foundation elements. The paper presents a simplified design procedure to evaluate the loads in piles and prestressed anchors when simultaneously used in foundations under tension loads and high overturning moments. Although involving some necessary simplifications for the sake of design, the procedure keeps the main features of load transfer trom piles and anchors to the surrounding soil. The approximate method has been adopted by the authors in relevant projects in Brazil, whose long term satisfactory performance indicates its appropriate performance. Two practical examples have been selected to illustrate the application of the proposed method. It is shown that anchor prestressing plays an important role in limiting tension loads on the piles and controlling foundation eccentricity. The importance of monitoring for replacement of occasional prestress losses to prevent long-term pile overstressing is illustrated.
The simultaneous use of piles and prestressed anchors in foundation design
Simultane Verwendung von Pfählen und vorgespannten Ankern bei der Auslegung von Gründungen
Danziger, F.A.B. (Autor:in) / Danziger, B.R. (Autor:in) / Pacheco, M.P. (Autor:in)
Engineering Geology ; 87 ; 163-177
2006
15 Seiten, 14 Bilder, 6 Tabellen, 64 Quellen
Aufsatz (Zeitschrift)
Englisch
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