Keywords: biconvex and biconcave cable trusses, closed-form solutions, post-elastic analysis, stress-strain properties of cables, post-elastic strain of cables, post-elastic deflection.

In this paper, the closed-form solution for the post-elastic response of biconvex and biconcave prestressed cable trusses subjected to a uniformly distributed load is presented. The closed-form method for the particularly straightforward determination of a vertical uniformly distributed load applied over the entire span of a cable truss, and the accompanying vertical deflection corresponding to the post-elastic range of a cable truss, is described. In this solution, applying the Irvine's theory [1], the direct use of experimental data, such as the actual stress-strain properties of high-strength steel cables, is implemented [2,3]. The application of the described approach and derived equations is illustrated by numerical examples. The deflection of prestressed cable truss has been compared with the non-linear finite element results. The results obtained confirm the correctness of the derived equations and techniques as well as their physical importance.

Many national and international specifications for the design of structures with steel cable components are based on the partial safety factor method. Factors of safety vary, but the working elastic stresses are usually used for a rope or strand in the cable structures. In these cases the suspended cable will never enter the post-elastic region, nor should it. The post-elastic solution presented is useful when one needs to increase a utilization of the high-strength steel cables used in the suspended cable trusses and to decide what post-elastic extension with accompanying deflection is reasonable for the whole structure. The proposed closed-form solution allows one to make in two steps rapid and clear post-elastic behaviour analysis of prestressed cable trusses as follows. First, by the closed-form solution one allocates and directly specifies the intensity of the vertically distributed load corresponding to the post-elastic region. Thereon, the improved analysis can be done by the discrete finite element method. For the discrete analysis of the geometrically and parametrically non-linear cable trusses this initial value is required for the incremental procedure that is used for the solution.

It is believed, that the solution presented will lead to an improved analysis of prestressed cable trusses in the post-elastic region and to an improvement of their serviceability assessment, when the post-elastic behaviour is considered.

1

H.M. Irvine, "Cable Structures", The MIT Press, Cambridge, Mass., 1981.

2

S. Kmet, M. Tomko, J. Brda, "Non-linear time-dependent post-elastic analysis of suspended cable considering creep effect", Structural Engineering and Mechanics, 22(2), p.197-222, 2006.

3

S. Kmet, Z. Kokorudova, "Nonlinear analytical solution for cable truss", Journal of Engineering Mechanics, ASCE, 132 (1), 119-123, 2006. doi:10.1061/(ASCE)0733-9399(2006)132:1(119)

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