Literature Review of Design Standards for Creep and Shrinkage for Integral Abutment Bridge

By Gaurav Ajay Agrawal, Amde M. Amde

A scholarly paper submitted in partial requirement for fulfillment of MS degree

Following is the abstract of the paper-

Abstract- An integral abutment bridge is a bridge without any expansion and contraction joints in the superstructure and the deck is directly connected to abutments or piers which are directly connected to piles. Eliminating joints doesn’t allow inflow of water and dust and these hazardous chemical materials to flow to substructure which was deteriorating the substructure and thus has reduced lots of maintenance costs of the agencies. But eliminating joints created problems for resisting loads like creep and shrinkage. These create unwanted stresses and deflections. Furthermore, the agency codes like AASHTO LRFD or ACI 209 do not give any guidelines for the design of these loads. Thus, this paper discusses a literature review of design recommendations of creep and shrinkage on an integral abutment bridge. The paper discusses that the significant effect creep and shrinkage have on superstructure, redistribution of stresses and moments, the importance of using a type of backfill soil to reduce creep.

Summary of the paper-

Integral Abutment Bridge ( IAB) eliminates substructure deterioration problem by eliminating joints. The absence of joints creates problems to resist secondary loads and stresses. Secondary loads include creep and shrinkage. Gaurav conducted a literature review of 5 literature pieces regarding that and wrote a paper and defended the paper in front of a supervisory committee of Dr. Chung C. Fu and Dr. Amde M. Amde.

After thorough literature, Gaurav found that-

1) There is redistribution of moments once creep and shrinkage act.

2) Pile curvature is also affected by superstructure creep and shrinkage.

3) Shrinkage causes deck contraction.

4) Codes like AASHTO and ACI do not provide specific guidelines for IAB design.

5) Girder deflection due to creep and shrinkage is greater then deflection due to instantaneous loadings with a factor ranging from 1 to 5 in different studies and different types of bridges.

After a thorough literature review, Gaurav concluded that-

1) AASHTO model for creep and shrinkage can be used for IAB creep and shrinkage design.

2) The same conclusion for ACI 209 code as well but with a modification that humidity correction formula needs to provide more humidity ranges rather than just 40% limit as real humidity of bridges in the US is around 70-80%.

3) Backfill soil type affects superstructure creep and using dense soil is recommended for less creep.

4) Redistribution of stresses creates residual stresses and thus transformed section analysis can be used for analysis.

5) Creep and Shrinkage cause stress reversal and adverse effects on the structure design.

Some pictures and their references used in the paper-

Time-dependent change in bending moment at interior support(Munuswamy, 2004)

This picture shows that continuous IAB moment is comparable to normal continuous bridge moment.

Time-dependent changes in stresses for AASHTO model(Munuswamy, 2004)

In this picture, huge stress, strain, and deflection jump are observed at 61 days and 181 days and stress reversal as well for prestressed IAB.

Tendency of computed and measured Pile Curvature(Huang, French, & Shield, 2004)

In this picture, pile curvature measured is in agreement with computed values

Residual stresses due to Shrinkage (Eriksen, et al., 2012)

Abutment displacement for 75 years of data for varying soil condition (Muhammad, Abdullah, & Yassin, 2015)

Displacement for various soils with and without creep can be seen in this picture

2D analysis Results for shrinkage strains(Frosch & Lovell, 2011)

This picture shows shrinkage causes contraction in the deck.

Note: The following is the list of 5 literature pieces used for the review in this paper. Also, all the above figure are taken from them and used for purely educational purposes only-

· Creep and Shrinkage Effects on Integral Abutment Bridges by Sivakumar Munuswamy, 2004

· Behavior of Concrete Integral Abutment Bridges by Jimin Huang, Catherine E. French, Carol K. Shield, 2004

· Economic and durable design of composite bridges with integral abutments (INTAB+) by Feldmann, Naumes and Pak 2012

· Long-Term Response Prediction of Integral Abutment Bridge Under Time-Dependent Effect by Muhammed, Abdullah, Yassin 2015

· Long Term Behavior of Integral Abutment Bridge by Frosch and Lovell 2011