Civil Engineering / İnşaat Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/13

Browse

Filters

2007 - 200922010 - 20121

Settings

Access Right: Open AccessAuthor: search.filters.author.Helwig, Todd A.

Search Results

Now showing 1 - 3 of 3
  • Article
    Citation - WoS: 10
    Citation - Scopus: 13
    Buckling Behavior of Steel Bridge I-Girders Braced by Permanent Metal Deck Forms
    (American Society of Civil Engineers (ASCE), 2012) Eğilmez, Oğuz Özgür; Helwig, Todd A.; Herman, Reagan
    Permanent metal deck forms (PMDFs) are often used in the bridge industry to support wet concrete and other loads during construction. Although metal formwork in the building industry is routinely relied on for stability bracing, the forms are not permitted for bracing in the bridge industry, despite the large in-plane stiffness. The forms in bridge applications are typically supported on cold-formed angles, which allow the contractor to adjust the form elevation to account for changes in flange thickness and differential camber between adjacent girders. Although the support angles are beneficial toward the constructability of the bridge, they lead to eccentric connections that substantially reduce the in-plane stiffness of the PMDF systems, which is one of the reasons the forms are not relied on for bracing in bridge applications. This paper documents the results of an investigation focused on improving the bracing potential of bridge deck forms. Modifications to the connection details were developed to improve the stiffness and strength of the forming system. Research included buckling tests on a 15-m (50-ft) long, twin-girder system with PMDFs for bracing. In addition, twin-girder tests were also used to validate computer models of the bracing systems that were used for parametric finite-element analytical studies. The buckling test results demonstrated that modified connection details make PMDF systems a viable bracing alternative in steel bridges, which can significantly reduce the number of cross-frames or diaphragms required for stability bracing of steel bridge I-girders during construction.
  • Article
    Citation - WoS: 6
    Citation - Scopus: 7
    Lateral Stiffness of Steel Bridge I-Girders Braced by Metal Deck Forms
    (American Society of Civil Engineers (ASCE), 2009) Eğilmez, Oğuz Özgür; Herman, Reagan S.; Helwig, Todd A.
    The lateral-torsional buckling capacity of steel bridge girders is often increased by incorporating bracing along the girder length. Permanent metal deck forms (PMDF) that are used to support the wet concrete deck during bridge construction are a likely source of stability bracing; however, their bracing performance is greatly limited by flexibility in the connections currently used with the formwork. This paper outlines results from a research study that assessed and improved the bracing potential of metal deck forms used in bridge applications. The research study included shear tests of PMDF panels, and also lateral displacement and buckling tests of twin girder systems braced with PMDF. This paper will provide key results from the shear panel tests and then focus on the lateral displacement tests. Parametric investigations of PMDF bracing behavior were conducted using finite-element analyses and the results from the lateral displacement tests served a critical role in calibrating the finite element models. This paper documents key results from lateral load tests of 17 girder-PMDF systems using a variety of bracing details and PMDF thickness values. © 2009 ASCE
  • Article
    Citation - WoS: 10
    Citation - Scopus: 15
    Stiffness and Strength of Metal Bridge Deck Forms
    (American Society of Civil Engineers (ASCE), 2007) Eğilmez, Oğuz Özgür; Helwig, Todd A.; Jetann, Charles A.; Lowery, Richard
    Light gauge metal sheeting is often utilized in the building and bridge industries for concrete formwork. Although the in-plane stiffness and strength of the metal forms are commonly relied upon for stability bracing in buildings, the forms are generally not considered for bracing in steel bridge construction. The primary difference between the forming systems in the two industries is the method of connection between the forms and girders. In bridge construction, an eccentric support angle is incorporated into the connection details to achieve a uniform slab thickness along the girder length. While the eccentric connection is a benefit for slab construction, the flexible connection limits the amount of bracing provided by the forms. This paper presents results from the first phase of a research study investigating the bracing behavior of metal bridge deck forms. Shear diaphragm tests were conducted to determine the shear stiffness and strength of bridge deck forms, and modified connection details were developed that substantially improve the bracing behavior of the forms. The measured stiffness and strength of diaphragms with the modified connection often met or exceeded the values of diaphragms with conventional noneccentric connections. The experimental results for the diaphragms with the modified connection details dramatically improve the potential for bracing of steel bridge girders by metal deck forms.