Doctoral Dissertations

Author

Xinbao Yang

Abstract

"This dissertation, consisting of six technical papers, presents the results of research on the theme of developing engineering and the construction specifications for externally bonded FRP composites. For particular, the work focuses on three critical aspects of the performance of FRP systems: fiber misalignment, comer radius, and lap splice length. Based on both experimental and theoretical investigations, the main contribution of this work is the development of recommendations on fiber misalignment limit, minimum comer radius, lap splice length to be used as guidance in the construction practice of FRP strengthening of concrete structures.

The first three papers focus on the strength and stiffness degradation of CFRP laminates from fiber misalignment. It was concluded that misalignment affects strength more than stiffness. In practice, when all fibers in a laminate can be regarded as through fibers, it is recommended to use a reduction factor for strength and no reduction factor for stiffness to account for fiber misalignment. Findings from concrete beams strengthened with misaligned CFRP laminates verified these recommendations.

The fourth and fifth papers investigate the effect of comer radius on the mechanical properties of CFRP laminates wrapped around a rectangular cross section. A unique reusable test device was fabricated to determine fiber stress and radial stress of CFRP laminates with different comer radii. Comparison performed with finite element analyses shows that the test method and the reusable device were viable and the stress concentration needs to be considered in FRP laminate wrapped comers. A minimum of 1.0 in. comer radius was recommended for practice.

The sixth paper summarizes the research on the lap splice length of FRP laminates under static and repeated loads. Although a lap splice length of 1.5 in. is sufficient for CFRP laminates to develop the ultimate static tensile strength, a minimum of 4.0 in. is recommended in order to account for repeated loads"--Abstract, page iv.

Advisor(s)

Nanni, Antonio
Chen, Genda

Committee Member(s)

Cheng, Franklin Y.
Belarbi, Abdeldjelil
Dharani, Lokeswarappa R.

Department(s)

Civil, Architectural and Environmental Engineering

Degree Name

Ph. D. in Civil Engineering

Comments

The financial support from the Federal Highway Administration (FHWA) and the University Transportation Center based at UMR are gratefully acknowledged.

The Federal Highway Administration is gratefully acknowledged for financially supporting this research under contract DTFH 61-00X-00017. The research was undertaken in the Center for Infrastructure Engineering Studies at University of Missouri--Rolla.

Publisher

University of Missouri--Rolla

Publication Date

Fall 2001

Journal article titles appearing in thesis/dissertation

  • Strength and Modulus Degradation of CFRP Laminates from Fiber Misalignment
  • Concrete Beams Strengthened with Misaligned CFRP Laminates
  • Effect of Fiber Misalignment on FRP Laminates and Strengthened Concrete Beams
  • Effect of Comer Radius on the Performance of Externally Bonded FRP Reinforcement
  • Stresses in FRP Laminates Wrapped Around Corners
  • LAP Splice Length and Fatigue Performance of FRP Laminates

Effect of Fiber Misalignment on FRP Laminates and Strengthened Concrete Beams

Pagination

xviii, 166 pages

Note about bibliography

Includes bibliographical references.

Rights

© 2001 Xinbao Yang, All rights reserved.

Document Type

Dissertation - Restricted Access

File Type

text

Language

English

Thesis Number

T 8010

Print OCLC #

49998507

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