Inelastic Design of Continuous-Span Composite Plate Girder Bridges by LRFD Method

비탄성 설계법에 의한 플레이트 거더 연속교의 LRFD 설계

  • 조은영 (명지대학교 토목환경공학과 구조연구실) ;
  • 신동구 (명지대학교 토목환경공학과)
  • Received : 2008.04.02
  • Accepted : 2008.06.30
  • Published : 2008.08.10

Abstract

The inelastic design of the three-span continuous composite plate girder with consideration of moment redistribution over the interior pier is performed using the LRFD method. The design of the girder section, based on the inelastic method, is compared with that by the conventional elastic design. The length of the center span for the three-span continuous bridge ranges from 40m to 70m and the relative ratio of the span length is assumed to be 4:5:4. Although the AASHTO- LRFD specifications are applied in the design of the composite girder, the recently proposed new design live load is used. After determining the maximum positive and negative sections by the elastic design for various limit states, the amount of moment redistributed to the maximum positive moment section is calculated. With the increased design moment due to moment redistribution from the interior pier, the maximum positive section designed by the elastic method is checked for the strength limit state and the service limit state. The maximum negative moment section is redesigned by reducing the size of the steel girder relative to the section designed by the elastic method and the new section is checked for the service limit state. Based on the design results for the five bridges considered in this study, it is estimated that about 23% of steel can be saved in the interior pier section if it is designed by the inelastic method compared with that designed by the elastic method.

Acknowledgement

Supported by : 교량설계핵심기술연구단

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