کاهش در تغییر شکل ناشی از گسل
Abstract
1. Introduction
2. Smart barrier with sacrificial members
3. Numerical simulation
4. Sacrificial members for bridges
5. Conclusions
References
Abstract
Contemporary analysis–design methods against faulting can significantly improve life-safety, but the problem of permanent deformation persists. This paper proposes a novel mitigation technique, addressing post-seismic serviceability. A “smart” barrier is employed to divert the fault rupture, introducing a minimum energy path. The “smart” barrier consists of two sheet-pile walls, connected with rows of sacrificial members. The latter are steel rings, whose performance is a function of geometry. The proposed system can be produced in the form of prefabricated panels, and its performance is largely insensitive to site conditions or workmanship. The barrier is compressed, absorbing tectonic deformation with minimum disturbance to the protected structure. The problem is analyzed employing the FE-method, using a thoroughly validated soil constitutive model with strain softening, confirming the efficiency of the mitigation concept. Further analyses demonstrate the use of sacrificial rings to protect continuous bridge decks, being installed between the deck and the bearings.
Introduction
Recent major earthquakes, such as Kocaeli and Düzce (Turkey, 1999), Chi-Chi (Taiwan, 1999), Wenchuan (China, 2008), Kaikoura (New Zealand, 2016) and Kumamoto (Japan, 2016) have shown that faulting-induced ground deformation can cause substantial damage to critical infrastructure (e.g., [34,35,33,15,27,20,28]). One such example is shown in Fig. 1, referring to the failure of the Shih Kang dam in Taiwan, due to 9 m of upthrust by the notorious Chelungpu fault during the 1999 Chi-Chi earthquake. However, several examples of satisfactory performance of a variety of structures have also been observed in past earthquakes (e.g., [11,4,5,16]). Motivated by the need to develop design methods for faulting–hazard mitigation, the interaction of fault ruptures with foundation–structure systems was explored during the QUAKER project. Combining field studies [4,5], centrifuge model tests conducted at the University of Dundee [13], and numerical analyses [8], a thoroughly validated analysis and design methodology has been developed. The foundation system was shown to play a crucial role, with continuous and rigid foundations being advantageous. The concurrent design methods have been applied to a variety of projects, including buildings, bridges, and tunnels (e.g., [1,3,2,9]). The methods developed so far can significantly improve life-safety, but the problem of permanent deformation (rigid-body rotation) has not been resolved. While the structure may survive, it must subsequently be demolished, imposing severe socio-economic consequences.