Numerical Simulation of Soil Structure Interaction in Pile-supported Integral Bridges

June 11, 2020

Example #1. Integral bridge on piled bank seats 


Limit equilibrium methods- Depth of soil affected by abutment movement can be identified without soil-structure  interaction analysis
- Thermal movement ≤ 40 mm;
- Skew ≤ 30°


PD 6694-1:2011 9.4.4 Horizontal soil pressures on end screen and abutments that accommodate thermal movements by translation without rotation


SSI 001SSI 003

SSI 004


3 Methods to consider soil properties in midas Civil


(1) Pile springs – user-defined p-y curves 


SSI 005

(2) Pile springs – built-in p-y curves


SSI 006

(3) Pile springs – Method of subgrade reaction (used in this example)


SSI 007


Applying Temperature Loads and Results


SSI 008

SSI 009


Apply Earth Pressure based on PB6694-1


SSI 010

SSI 011


Envelope Results by Load Combination


SSI 012

SSI 013



Example #2. Integral bridge with full height abutments supported on a single row of piles


Soil–structure interaction- Depth of soil affected by abutment movement cannot be easily identified unless a soil-structure interaction analysis is performed
- Thermal movement > 40 mm;
- Skew > 30°
- Over-consolidated back-fill material
- Layered soils


PD 6694-1:2011 9.4.5 Horizontal earth pressures on full height frame abutments on piles and embedded wall abutments (soil– structure interaction analysis)


SSI 016


Soil structure interaction model can be generated with midas GTS NX. In order to consider the variable elastic modulus, we can imply import the materiel properties from Excel into GTS NX and assign them to each soil layers.



SSI 017

SSI 018

SSI 019

Construction stage analysis with 5 stages considering structure and back-fill soil construction with temperature loads has been performed. The stress profile from soil is obtained and compared with earth pressure applied to abutment to obtain H'(depth of soil influenced by the abutment movement) and d'(the moment of the structure at a depth H'/2 due to an expansion or contraction of the end of deck). Update Soil Shear Modulus, R_FG, and young's modulus in GTS NX model file and update the results again. By doing this iterative analysis again, we can obtain the converged results.


SSI 020

SSI 021

SSI 022

Watch the full webinar video


Subscribe S.O.S Newsletter

About the Author
Pere Alfaras | Principal Bridge Engineer | Arcadis UK

Alfaras has more than 12 years of experience in bridge and structural design. He has also been a renowned lecturer at UPC/Barcelona Tech for 5 years and his main focus was on Finite Element Methods.

Download Download the Webinar
Presentation file

midas Civil project tutorial of the Numerical Simulation of
Soil Structure Interaction in Pile-supported Integral Bridges

Read all