Journal of Constructional Steel Research 67 (2011) 1325–1340 Contents lists available at ScienceDirect Journal of Constructional Steel Research journal homepage: www.elsevier.com/locate/jcsr Sensitivity analysis of tensegrity systems due to member loss B. Shekastehband, K. Abedi ∗ , M.R. Chenaghlou Department of Civil Engineering, Sahand University of Technology, Tabriz, Iran article info Article history: Received 3 May 2010 Accepted 6 March 2011 Keywords: Tensegrity systems Self-stress Sensitivity Gradual member loss Sudden member loss Nonlinear static and dynamic analysis Progressive collapse abstract Tensegrity systems typically contain a large number of members, and possess a high degree of statically indeterminacy. However, a number of members are critical to system integrity and serious strength reductions can be produced by loss of any of them. Furthermore, when these members are lost suddenly, their forces are shed in a dynamic manner into the structure, causing more severe damage. This paper presents a numerical study on the sensitivity of tensegrity systems to both gradual and sudden member losses, taking into account both geometric and material nonlinearities. Also, other parameters, considered in this work, include the self-stress level, slenderness ratios of struts and damping ratios. The conclusions, drawn from this study, can in turn, lead to the suggestion of some guidelines for the design of such systems. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction Tensegrity systems are innovative systems in the spatial structures field and refer to a special type of tensile structures that can offer an alternative to traditional space structures. A tensegrity structure is defined as ‘‘a system in a stable self equilibrated state comprising a discontinuous set of compressed components inside a continuum of tensioned components’’ [1]. These systems exist under pre-stressed (self-stressed) configurations. The initial stresses contribute to the system’s rigidity and stability. Tensegrity systems have specific advantages that merit their consideration for use as engineering structures. First, most tenseg- rity structures are lightweight structures, making them suitable for various space applications [2]. Second, their members can serve simultaneously as sensors, actuators and load carrying el- ements. Therefore, having incorporated sensors and actuators, tensegrity structures have considerable promise as smart struc- tures [2]. Third, for using as a mechanism in the folding process, the lengths of the tension links (cables) can be easily adjusted. The folding and deployment capabilities of these systems will al- low the use of tensegrity systems as deployable space structures with promising future aerospace applications. Fourth, tensegrity systems are capable of large displacement, belonging to the class of flexible structures [3]. There are also several disadvantages that must be overcome to make tensegrity structures useful. First, most tensegrity systems ∗ Corresponding author. Tel.: +98 4123459096; fax: +98 4124343. E-mail addresses: b_shekastehband@sut.ac.ir (B. Shekastehband), k_abedi@sut.ac.ir (K. Abedi), mrchenaghlou@sut.ac.ir (M.R. Chenaghlou). are not conventionally rigid; they usually exhibit an infinitesimal mechanism and must be pre-stressed to resist deformation in the direction of the mechanism [4,5]. Second, tensegrity systems generally tend to be susceptible to vibration because of the infinitesimal mechanism [5]. Third, tensegrity systems only exist under specific geometries. The nodal positions cannot be specified arbitrarily for a tensegrity structure. Thus, some positions cannot be achieved with a tensegrity structure [6]. Tensegrity systems are mainly statically and kinematically indeterminate systems. They typically contain a large number of members, and possess a high degree of statically indeterminacy. The stability analyses performed on these systems have indicated that despite of high redundancy, buckling of a strut (or set of struts) or rupture of a cable may cause a progressive collapse to occur [7,8]. In fact, in the case of local collapse in which strut snap- through or cable rupture is occurred, a large amount of kinetic energy is released at a local region of the structure, which can cause the overall collapse of the system. There are some researches regarding the effect of member loss on the ordinary space trusses, studied by many researchers as Hanaor [9], Murtha-Smith [10], El-sheikh [11] and Malla [12]. It was illustrated that a loss of a member in a critical truss area was more serious than a loss in another area. Since this phenomenon was rapid, dynamic effects could develop, leading to a further damage in the space truss. Ben Kahla and Moussa [13] have performed a numerical investigation into the effect of sudden rupture of a cable component in a beam-like tensegrity system, without applying external loads, using nonlinear dynamic time history analysis. Oppenheim and Williams [5] examined the dynamic behavior of a simple elastic tensegrity structure. It is confirmed, analytically and numerically, that the energy decay 0143-974X/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.jcsr.2011.03.009