Dynamic analysis of temporary steel grandstand subjected to human-induced excitations due to jumping

Steel grandstands are structures that are frequently used during sport games and many other non-sporting events, such as festivals, music concerts, or even politicians rallies, with participation of a large number of attendees. Unfortunately, the presence of unexpected excessive dynamic loads due to unpredictable behaviour of spectators (e.g. synchronized harmonic jumping or swaying) may lead to serious structural damage or even total collapse of a structure, and such cases were observed in the past. Given that, steel grandstands should be designed so as to withstand the unexpected dynamic loads leading to damage and, therefore, ensure maximum safety for all participants. Building codes, however, apply different approaches. According to the Polish Standard, an additional horizontal load equal to 6% of the total vertical load acting on a grandstand has to be considered at the design stage. The British Standard, on the other hand, specifies a higher value of horizontal load, i.e. 10% of the total vertical load that should be taken into account. Therefore, the aim of the present paper is to conduct a dynamic numerical investigation focused on the response of a steel temporary grandstand subjected to human-induced vibrations due to jumping with two different values of horizontal load (6% and 10% of the total vertical load) as well as for two different bracing elements (typical tubular member and polymer damper). The results of the study clearly show that the response of a temporary steel scaffolding grandstand equipped with two different bracing elements taking into account two different approaches is substantially different.