Fiber Reinforced Polymer (FRP) steel bars experience significant cyclic loading in structural applications, with stress variations typically ranging from 0.4 to 0.6 of ultimate strength and exposure to environmental factors that can accelerate material degradation. Field measurements show that conventional steel reinforcement can experience fatigue failure after 10⁶ cycles under these conditions, particularly at critical connection points and areas of stress concentration.

The fundamental challenge lies in developing composite structures that maintain high tensile strength while achieving superior fatigue resistance through optimized fiber orientation and matrix bonding.

This page brings together solutions from recent research—including targeted carbon fiber sheet reinforcement, dual-orientation fiber systems with selective sizing compatibility, and pre-tensioned FRP reinforcement with controlled prestressing. These and other approaches focus on practical implementation strategies that enhance both durability and structural performance under cyclic loading conditions.

1. Fiber-Reinforced Composites with Advanced Fiber Integration for Enhanced Mechanical Properties

SAVEETHA INSTITUTE OF MEDICAL AND TECHNICAL SCIENCES, 2025

Fiber-reinforced composites (FRCs) with enhanced mechanical properties that meet modern engineering demands through optimized fiber reinforcement. The invention focuses on developing FRCs with improved performance characteristics, particularly in applications requiring enhanced durability, sustainability, and recyclability.

2. Sandwich Panel System with Rigid Diaphragms and Composite Layer for Steel Box Girders

XIAN JIAOTONG UNIVERSITY, XINGTAI ROAD & BRIDGE CONSTRUCTION GROUP CO LTD, 西安交通大学, 2023

A sandwich panel system for steel box girder bridges that combines the benefits of composite deck construction with improved fatigue resistance. The system comprises a sandwich panel comprising an upper panel, lower panel, and a composite sandwich layer, with the upper and lower panels connected by rigid diaphragms. The composite sandwich layer is bonded between the diaphragms and the upper and lower panels, providing a strong and durable structural component. The diaphragms serve as a critical component in maintaining structural integrity during dynamic loading, while the composite sandwich layer enhances the panel's overall fatigue performance.

CN218291555U-patent-drawing

3. Fiber-Reinforced Composite with Dual Orientation and Selective Sizing Compatibility

Owens Corning Intellectual Capital, LLC, OWENS CORNING CAPITAL LLC, 2022

Fiber-reinforced composite materials with enhanced fatigue performance through optimized fiber orientation. The materials incorporate fabrics with specific fiber orientations where the reinforcing fibers' sizing compounds are compatible with the resin matrix, while the non-parallel fibers' sizing compounds are incompatible. This dual orientation approach enables improved bonding between the resin and fibers, leading to reduced fiber breakage and enhanced fatigue resistance in wind turbine blades.

4. Fiber Composite Beam with Longitudinally Aligned Internal Reinforcing Ribs

ZOOMLION HEAVY INDUSTRY SCIENCE & TECHNOLOGY CO LTD, 中联重科股份有限公司, 2022

A fiber composite beam structure for boom sections that enhances fatigue life through optimized reinforcement patterns. The beam comprises a hollow main body with strategically placed reinforcing ribs that extend along its longitudinal axis. These ribs are positioned on the inner surface of the main body, spaced apart in the circumferential direction, and are spaced in the circumferential direction. The beam's hollow main body maintains structural integrity while the ribs provide critical load-bearing support, significantly improving the beam's fatigue life compared to conventional designs.

CN215479347U-patent-drawing

5. BFRP-Steel Pipe Combined Chord Truss with Fiber-Reinforced Polymer Winding Layers

Shenyang University, SHENYANG UNIVERSITY, 2021

A corrosion-resistant, lightweight, high-strength BFRP-steel pipe combined chord truss that combines the structural integrity of a steel truss with the durability of composite materials. The truss comprises an upper chord, lower chord, and multiple web members, with each component featuring a fiber-reinforced polymer (FRP) winding layer structure perpendicular to the steel tube axis. The upper chord and lower chord employ parallel fiber adhesion layers, while the web members utilize a perpendicular fiber structure. This design provides superior stress performance and corrosion resistance, while maintaining the structural integrity of the truss.

CN215054554U-patent-drawing

6. Composite Steel and Fiber-Reinforced Polymer Stirrups with Ribbed FRP Layer and Fiber Cloth Wrapping

NANTONG PREFABRICATED BUILDINGS AND INTELLIGENT STRUCTURES INSTITUTE, Intelligent Fiber Composite Reinforcement Nantong Co., Ltd., 南通装配式建筑与智能结构研究院, 2020

Composite steel FRP stirrup with integrated reinforcement and corrosion protection. The stirrup comprises a steel reinforcing bar wrapped with a fiber-reinforced polymer (FRP) layer, with the FRP layer featuring ribs and fiber cloth wrapping. This integrated design combines the structural integrity of steel with the corrosion-resistant properties of FRP, enabling the creation of durable stirrups that can withstand harsh environments without compromising performance.

7. FRP Steel Pressure Bar with Composite Layered Structure and Integrated Pre-Tightening Block

Hunan Institute of Science and Technology, HUNAN INSTITUTE OF SCIENCE AND TECHNOLOGY, 2018

A novel FRP steel pressure bar featuring enhanced fatigue resistance through a unique composite structure. The bar comprises a bottom end portion, a top end connected with a gasket, and a top end connected with a lower end portion. The top end of the lower end portion is connected with an upper end seat, and the top end of the upper end seat is connected with an upper end portion. The inner cavity of the upper end portion is provided with a carbon steel layer, and the inner side of the carbon steel layer is covered with an aluminum alloy layer. A second FRP layer is applied on the aluminum alloy layer, and a pre-tightening block is embedded in the joint between the upper end seat and the upper end portion. Solder legs are welded to the left and right sides of the pre-tightening block, and the soldering feet are positioned away from the pre-tightening block. A plug is welded to one side of the block, and a cavity is mounted on the inner cavity of the upper end portion. A locking sleeve is mounted on the inner cavity of the upper end seat and the card seat, with side rods positioned between the sleeve and the soldering legs. This configuration enables the bar to maintain structural integrity under cyclic loading

CN208072773U-patent-drawing

8. Composite Rib with Steel Wire and Basalt Fiber Filament Agglomeration and Spiral Coating

ZHENGZHOU DENGDIAN CBF CO LTD, 2018

A basalt fiber reinforced composite rib that addresses the limitations of traditional steel bars. The rib combines steel wires with basalt fiber bundles, arranged in agglomerated filaments. The outer layer of these filaments is spirally coated, forming a composite rib with enhanced mechanical properties compared to conventional steel bars. The coated layer provides improved corrosion resistance and durability while maintaining the structural integrity of the composite material.

CN108130983A-patent-drawing

9. Method for Extending Steel Beam Fatigue Life Using Targeted Carbon Fiber Sheet Reinforcement

China Metallurgical Construction Research Institute Co., Ltd., MCC CENTRAL RESEARCH INSTITUTE OF BUILDING AND CONSTRUCTION CO LTD, 2017

A method for extending the fatigue life of steel beams through targeted reinforcement. The method employs carbon fiber sheets bonded to the web's top flange surface, with the sheets strategically positioned to cover specific areas of high fatigue potential. The carbon fiber sheets are applied through a controlled application process, ensuring precise alignment and distribution across the beam's critical sections. This targeted reinforcement approach enables comprehensive protection against fatigue failure by addressing critical stress concentrations.

10. Pre-Tensioned FRP Reinforcement System for Structural Beams and Plates with Controlled Prestressing

Nanjing Tech University, NANJING TECH UNIVERSITY, 2017

A pre-tensioned FRP reinforced beam, plate, or composite structure that enhances seismic performance and fatigue life through controlled prestressing. The beam, plate, or composite structure comprises a pre-tensioned FRP reinforcement system that is applied to a concrete beam plate, wood beam board, wood-composite beam plate, steel beam plate, or steel-concrete composite beam plate. The prestressing system is designed to provide significant stiffness enhancement while maintaining the structural integrity of the beam, plate, or composite, thereby improving seismic response and reducing the risk of premature failure during seismic events.

CN206245775U-patent-drawing

11. Composite Bar with Fiber-Reinforced Polymer Wrapping Layer Integrating Reinforcing Bar

ZHIXING FIBER COMPOSITE REINFORCEMENT NANTONG CO LTD, Intelligent Fiber Composite Reinforcement Nantong Co., Ltd., 2017

A composite bar comprising a reinforcing bar and a wrapping layer, where the wrapping layer is made of a fiber-reinforced polymer. The composite bar provides exceptional strength, modulus, corrosion resistance, and elongation properties, making it a superior replacement for traditional steel and wire components in construction and bridge structures. The wrapping layer integrates the reinforcing bar and wrapping material into a single, continuous structure, eliminating the need for separate components. This design enables precise control over fiber orientation, wrapping configuration, and material properties, resulting in optimized performance and reduced material waste.

12. Steel-Glass Fiber Composite Rib with Radial Arrangement and Spiral Wound Resin Bonding

Wuhan University of Technology, WUHAN UNIVERSITY OF TECHNOLOGY, 2017

Radially arranged steel-glass fiber composite rib for reinforced concrete structures with enhanced ductility and improved load-bearing capacity. The rib is produced by processing a steel sheet through pultrusion followed by fiber winding, sandblasting, and heat curing. The composite rib features a steel core with continuous glass fiber reinforcement, which is bonded to the steel core using a resin. The rib is then formed through a spiral winding process, resulting in a composite rib with improved fiber alignment and resin bonding. The rib's unique design enables enhanced ductility compared to traditional steel-glass fiber composite ribs, while maintaining high tensile strength and corrosion resistance.

13. Pultruded Bar with Dual Fiber Reinforcement Structure Incorporating Interlaced Bulky Fibers

YOUKUN LONG, 2016

Pultruded bar with enhanced mechanical properties through optimized fiber reinforcement distribution. The bar combines a smooth, glass fiber-reinforced matrix with a puffed structure containing bulky fibers that interlace with the matrix. This dual reinforcement approach significantly improves lateral strength while maintaining the bar's smooth surface finish. The puffed fibers enhance the bar's overall mechanical performance, particularly under repeated bending loads, while maintaining its aesthetic appearance.

14. Composite FRP Tendons with Carbon Fiber Winding and Thermosetting Resin-Embedded Bars

UNIV ZHENGZHOU, 2016

Composite FRP tendons for engineering structures that enhance durability and performance in corrosive environments. The new tendons feature a unique construction where carbon fiber bundles are wound around thermosetting resin-embedded FRP bars. The resin is cured during the carbon fiber application process, creating a reinforced composite structure with enhanced mechanical properties, including improved elastic modulus and shear strength compared to conventional FRP reinforcement. The composite structure maintains its strength and deformation capacity even after exposure to corrosive environments, while maintaining the necessary bonding characteristics for structural integrity.

15. Composite Component with Integrated Reinforcement Areas Using Differential Fiber Strength and Orientation

ENRICHMENT TECHNOLOGY COMPANY LTD, 2015

A composite component with integrated reinforcement areas that absorb loads during operation while maintaining structural integrity. The component comprises a composite area with normal areas containing first fibers and reinforcement areas containing second fibers, where the second fibers have a higher strength than the first fibers. The reinforcement areas are strategically positioned to distribute loads effectively, with the second fibers oriented in the direction of force application. This design enables efficient load absorption while maintaining the structural integrity of the composite material.

US2015314557A1-patent-drawing

Get Full Report

Access our comprehensive collection of 15 documents related to this technology