Ductility of Welded Steel Columns

Abstract and project information last updated: 12 March 2013. Project updates are dated below.

A large steel column with small square sensors and wires attached is at center, with spots of blue adhesive along it.

Credit: Steven Fulmer

Pictured is an instrumented test set-up that represents an example of Optotrak Motion Sensing System Instrumentation. The test is part of a collaborative research project between AUTC and North Carolina State University that is a continuation of an ongoing project that investigated bridge and marine structure design practices.

AUTC
Project
Number
410001
Principal
Investigator
Mervyn Kowalsky (NCSU)
kowalsky@ncsu.edu
Funding
Agency

US Department of Transportation (RITA)

Alaska Department of Transportation & Public Facilities

Project
Budget
307660
Start
Date
1 July 2010
Estimated
End Date
31 December 2012

Abstract

This research, a joint effort between AUTC and North Carolina State University, is a continuation of an ngoing project that investigated bridge and marine structure design practices, aiming to identify improved connection design approaches to produce the necessary ductility and energy absorbing capacities required for satisfactory designs in Alaska. Through earlier testing, researchers not only proved what methods were inadequate (such as the current practice of fillet-welding the cap beam to the pile as well as an alternative welding methods) but also confirmed that a new method of using a plastic hinge-relocating concept was more successful. This method utilized a round steel column capital in which the top portion welded to the cap beam is thicker than the bottom thinner portion welded to the pile. The approach successfully reduced the inelastic demands of the cap beam weld, and forced the inelastic action to occur in the pile itself. Current research includes optimizing the new design to improve displacement capacity and ductility in bridge and marine structure design, as well as investigating additional connection designs proposed by ADOT&PF engineers. The research will result in a series of design recommendations consistent with the various levels of seismicity found within Alaska. The primary benefit will be the improved design and performance of steel bridges and marine structures containing similar connections.

Final Report

Seismic Performance of Steel Pipe Pile to Cap Beam Moment Resisting Connections
19 Feb 2013

Seismic Performance of Steel Pipe Pile to Cap Beam Moment Resisting Connections
Steven J. Fulmer, Mervyn J. Kowalsky, James M. Nau
410001.Kowlasky.FINAL_.pdf

Related Project Activity

3 June 2011

Ductility of Welded Steel Column Test 2 Summary Report

by billy.connor

Steel Bent Phase 2 – Test 2 Report

The test 2 specimen consisted of a composite connection configuration utilizing shear stud connectors placed on the outside the pile section which was inserted into a larger stub pile section that contained a matching pattern of shear studs. The annular space formed between the two components was filled with flowable grout allowing for composite action to develop the moment connection by transferring forces from the pile to the cap beam via the stub pile, while avoiding inelasticity in critical welded regions. The results of experimental testing showed the connection capable of successfully developing a flexural hinging mode of failure in the form of pile wall local buckling at the intended region.

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