Date of Graduation

5-2020

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Degree Level

Graduate

Department

Civil Engineering

Advisor/Mentor

Heymsfield, Ernest

Committee Member

Murray, Cameron D.

Second Committee Member

Prinz, Gary S.

Keywords

concrete shrinkage; concrete creep; ARDOT; Gara Model; concrete stresses

Abstract

Early age bridge deck cracking is a common problem throughout the United States. Early age cracking develops shortly after the deck is poured. It reduces the serviceability and lifespan of bridges. Early age cracking can be typically attributed to either of two factors, 1) construction practices, and 2) shrinkage. The Arkansas Department of Transportation (ARDOT) has experienced early age bridge deck cracking. ARDOT currently specifies a sequence deck pour on most of their bridges; however, contractors prefer continuous deck pours because of ease and construction time. During the period of this TRC1903 research project, ARDOT has only approved a few continuous pours for relatively short bridges, 180 to 190 ft. long. Concrete cracking occurs when concrete tensile stresses exceed the concrete’s tensile strength. Therefore, early age bridge deck cracking is evaluated in this thesis be monitoring induced concrete tensile stresses and comparing these values with the concrete’s concurrent tensile strength. Bridge site visits at bridges constructed using a continuous deck pour process were conducted to study deck cracking patterns in newly constructed bridges and identify deck sections that were experiencing cracking. In addition to a visual approach for identifying sections experiencing cracking, a numerical method was used. Finite element bridge models were created using ABAQUS to compare numerical modeling results to field recorded results attained from a bridge instrumented with strain gauges cast inside the concrete deck. Additional numerical models were made to verify the modeling techniques used by the author by validating calculated stresses with numerical models in the literature. The Finite element models were specifically developed to model the bridge deck construction process. Therefore, time dependent loads and material properties were considered in the numerical model. Concrete material time dependency was estimated using the Eurocode specifications (CEN., 1992). In addition, concrete stresses were calculated in this thesis using the Eurocode modular ratio approach.

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