Seismic Pressures on Retaining Walls 

 

Introduction

 

The determination of seismic earth pressures acting against retaining walls is a complex soil-structure interaction (SSI) problem. Factors which affect these earth pressures include:

  1. The nature of the input motions which includes the amplitude, frequency, directivity and duration of the motion.
  2. The response of the soil behind, in front & underlying the wall.
  3. The characteristics of the wall, which includes the strength and bending stiffness of the wall.

 

The pseudo-static class of analysis is most commonly used in design and makes use of the free-field Peak Ground Acceleration (PGA ) expressed as a Seismic coefficient, C  (/g) typically obtained from national design standards (e.g., NZTA Bridge Manual, 2014).

 

 

Pseudo-static analyses

 

1.  Flexible (Mononobe-Okabe)

2.  Stiff (Matthewson et al., 1980)

 

  

3.  Rigid (Matthewson et al., 1980)

  

Question:  Can Co  be optimized for New Zealand?

 

Project

 

  • Perform two-dimensional dynamic finite element analyses using OpenSees Consider 2 soil classes (Classes C &D) (NZS 1170.5:2004)
  • Use appropriate NZ acceleration-time histories for two zones in North Island & one for South Island, and allowance for magnitude scaling
  • Analyses for two embedded cantilever wall heights (2m and 3m) & one double propped wall height (3m, with two different prop stiffnesses)
  • Carried out 946 dynamic analyses run

 

 

Example results for Christchurch, Shallow Soils, Soil Class C

 

 

 

 

Recent updates

x%

 
Last updated: 24/09/15
 

TIMELINE

 

Timeline placeholder

 

LAST THREE MONTHS

 

• Project completed on budget and a final report was issued on 21/8/15. A further revised copy of the report was submitted due to typographical revisions and was submitted on 9/9/15.

 

 

NEXT THREE MONTHS

 

•  N/A

 

 

CURRENT OBSTACLES

• N/A

 

MITIGATION

• N/A

 

Recommended Seismic Coefficients for use in Pseudo-Static Analysis

 

North Island 1: Auckland, Hamilton & New Plymouth, North Island 2: Wellington and Palmerston North and South Island 1: Christchurch.

 

          

 

 

 

 

 

 

 

 

  

 

  

Proudly Supported By

To read more about our supporters please select their logo

 

Our Major Sponsors


 


 


 


Christchurch Website Design