Testing Requirements of Hysteretic Energy Dissipating Devices According to Italian Seismic Code

Abstract

Anti-seismic displacement dependent devices are used to improve the dynamic characteristics of the structural system of buildings and bridges. Performance and functional requirements of energy dissipating devices are specified in most new seismic design codes. In this paper nonlinear dissipative capacity of hysteretic dampers is evaluated by specific experimental tests and compared with the Italian code testing requirements. Quasi-static and dynamic experimental testing have been performed on U-shaped flexural steel plates (UFPs) devices. Controlled-displacement tests considering a specific loading protocol have been performed to define the cyclic behavior of UFPs. Shaking table testing considering a random sequence of seismic inputs have been carried out on a 3D, 2:3 scaled, three-storey posttensioned timber framed building with dissipative bracing systems based on UFPs. The reliability of the testing procedures required by codes for prototype and production control tests is discussed in terms of number of cycles and of cycles to failure.

Seismic Design and Testing of Post-tensioned Timber Buildings With Dissipative Bracing Systems

“…During the experimental campaign, the intensity of the seismic inputs was progressively increased in acceleration for earthquakes 1,228, 196, and 535, from 10 to 100% of PGA, in order to provide additional information about the seismic performance frame response at varying levels of ground shaking (Table 1). In the case of braced post-tensioned frame configuration (BF) one UFP damper at the first story of the bracing system (UFP1) reached the failure condition during testing ID 187 at 100% of PGA level due to cyclic fatigue after almost 40 tests and more than 150 cycles to ductility µ DB > 2 sustained by the device (Ponzo et al, 2019). For the bare frame configuration (F) the PGA level was increased up to 75% because an imposed interlock of 2.5% of maximum inter-story drift was reached, except for the weaker earthquake input 1,228, at 100% of PGA (see Table 1).…”

“…Stable hysteretic behavior, without any sign of failure, has been observed during cyclic loading, maintaining almost the same energy dissipation capability. For more details about the design and testing of UFP dampers, please refer to Ponzo et al (2019). The proposed procedure is valid also for shear link devices, such as those proposed by Nuzzo et al (2018), as an alternative to UFP dampers if they do not modify the pattern of vertical loads in the beam.…”

A Dissipating Frames for Seismic Retrofitting and Building Energy-Efficiency

“…Among them, base isolation and energy dissipation are the most utilized protection techniques. Base isolation systems are principally categorized in elastomeric bearings, friction systems, and rolling systems, examples of which are found in [9][10][11][12][13][14][15]; energy dissipation systems, depending on their dissipative behavior, can be distinguished in hysteretic metal dissipaters [16][17][18][19][20], dissipative braces [21][22][23][24], or devices with different dissipative behavior [25][26][27][28][29][30][31][32]. Among them, a solution that somehow invokes dissipative braces consists of dissipative frames that are coupled to the existing structure [33][34][35].…”