Retrofit strategies for mitigating progressive collapse of hybrid and traditional cable domes

This paper is concerned with the retrofitting of hybrid cable domes against progressive collapse using viable proposed strategies. Hybrid cable domes as the composite forms of tensegrity rings and cable domes with appropriate structural efficiency offer promising alternatives for traditional cable domes with rigid compression rings. A hybrid configuration, namely, a hybrid cable dome with a tensegrity ring and a traditional Levy cable dome with a rigid ring, is assessed against progressive collapse using the Alternate Path (AP) method. The studies were carried out in two phases. In the first phase, using static and dynamic alternate path analyses, the pro-gressive collapse of the structures due to loss of critical members was assessed. In detecting critical members, two criteria were employed based on the members' demand and frequency of damaged structure. According to the obtained results, lower hoop cables were identified as critical members whose sudden loss resulted in progressive collapse. In the second phase, the effectiveness of four proposed retrofit strategies, entitled employing force limiting devices (FLDs), strengthening critical struts, adding an inclined bracing cable net in hoops, and using a network of bottom cables, were evaluated aimed to improve progressive collapse resistance. Based on the results, the proposed network of bottom cables was determined as the best retrofit method for mitigating the progressive collapse of hybrid and traditional cable domes.