The National Academies

NCHRP IDEA 20-30/IDEA 227 [Active (IDEA)]

Adjustable Cross-frames for the Erection of Steel Girder Bridges

  Project Data
Funds: $135,000
Staff Responsibility: Inam Jawed
Research Agency: University of Notre Dame
Principal Investigator: Ashley Thrall
Effective Date: 1/1/2021
Fiscal Year: 2020

This project will develop novel, cost-effective adjustable cross-frames for curved and highly skewed steel girder bridges that will enable necessary geometry adjustments in adjacent girders for fit-up while providing a single, permanent cross-frame. Work in Stage 1 will focus on conceptual design of the novel adjustable cross-frames as well as understanding bounds on desired adjustability and developing detailed control sequences. Bounds on what adjustability is needed and whether minor or major adjustment is warranted will be determined. High-fidelity finite element (FE) numerical analyses of 4-5 prototype structures during erection will be performed to determine bounds on girder twist and deflection. Conceptual design will be performed to develop forms for adjustable cross-frames to meet necessary geometric adjustments. For each adjustable cross-frames form, models developed in the earlier task will be used to understand forces developed through jacking and track relative motions of each girder of the prototype structures during adjustment. A control sequence will then be developed for each form. In Stage 2, concepts developed in Stage 1will be numerically evaluated relative to one another and to conventional rigid cross-frames for the prototype structures. A scaled prototype of the most promising design will be built, evaluated, and demonstrated. Research will culminate in recommendations on adjustable cross-frames, including bounds on its applicability.

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