Non-linear 2DOF system for efficient seismic analysis of vertical soil-nailed walls

Abstract

New non-linear analysis of a two-degree of freedom (2DOF) system is proposed to evaluate the seismic deformation of soil-nailed structures. The proposed method satisfactorily predicted the deformation of a soil-nailed structure under earthquake action and saved computational time for analysis of a practical problem in comparison with full non-linear time-history analysis developed within the finite difference approach. The 2DOF model is calibrated using a non-linear static procedure and the calibrated 2DOF model is used for non-linear time history analysis. The Non-linear static analysis was performed by applying a vertical load pattern behind the reinforced block at the top boundary of finite difference model. By applying the aforementioned load pattern, additional lateral pressure was mobilised behind the reinforced block. This additional lateral pressure allowed examination of the lateral resistance of the reinforced block and provided the non-linear system characteristics required to simulate the seismic response. Two models were selected and subjected to five different excitations with two amplitude scale factors to verify the proposed method using fully dynamic analysis. The results show that the elastic fundamental period of a structure with respect to the predominant period of input motion and the level of excitation control the level of deformation.

Keywords:

• soil-nailed
• displacement-based design
• dynamic analysis
• non-linear static analysis
• seismic design
• push-down analysis

Acknowledgement

The authors deeply appreciate the cooperation of Prof. A. Fakhimi for the use of the CA2 computer program.