Design and Operation of the Vibration-Based SHM System of the University Sports Hall in Campobasso

The University Sports Hall in Campobasso (Southern Italy) is a large structure with an interesting structural configuration. It consists of a number of inclined steel arches, made by tubular profiles, resting on reinforced concrete columns. The arches support the wooden roof, while pre-stressed steel cables, characterized by different sections, connect the heads of the columns supporting the various steel arches. In the first years after construction, the structure underwent some cracking problems at the head of the supporting columns, so the tensile loads applied to the steel cables were changed with respect to the design values and continuous monitoring of tensile loads in the six steel cables was recommended. Looking for a monitoring solution characterized by minimum impact on the operation of the structure, a vibration based Structural Health Monitoring (SHM) system for continuous monitoring of tensile loads in the steel cables was designed. It consists of a distributed measurement system based on six data acquisition modules, one for each cable, four miniature accelerometers per cable, and a centralized data processing system for continuous automated output-only identification of the fundamental modal parameters and subsequent tensile load estimation. The present paper illustrates the motivations supporting the adoption of a vibration-based SHM system for the structure, and the general theoretical background for tensile load estimation. Moreover, the hardware and software solutions for continuous monitoring of the cables are presented, together with some explanatory monitoring results.