Most of the bridges in the North America were built before the earthquake design procedures were developed and implemented. The contemporary seismic design practices of RC structures encourage the use of adequate means to prevent premature failure of members subject to inelastic cyclic loading. Recent earthquakes have repeatedly highlighted the vulnerabilities of the corroded and old RC bridges to seismic deformation demands.
The term seismic retrofitting refers to structural upgradation designed to enhance the resistance of an existing concrete member to seismic loads. The analysis and evaluation of a structure highlights the shortcomings which prevent the structure from performing and fulfilling established seismic standards. The rehabilitation process is then designed to upgrade a structure in terms of seismic response.
When bridges are evaluated, it is defined whether or not the bridge is functional and does its intended job. If a bridge structure cannot handle weight, traffic volume and speed or lacks in terms of safety, it is considered as structurally deficient. The implementation of corrosion control systems and seismic rehabilitation can extend the service life of a bridge.
The use of fiber reinforced polymer (FRP) is becoming increasingly common in the development of new concrete structures. However, reinforcement corrosion and structurally deficient structures represent one of the longstanding structural challenges. The composite materials (FRP) are high-performance materials that can be used for seismic rehabilitation of reinforced concrete bridge columns. The favorable properties of composite materials and appropriate seismic strengthening practices can enable a bridge to withstand heavy earthquakes. This is why seismic rehabilitation of old bridges is largely performed using FRP materials.
Related: The Application of FRP Composites in Bridge Structures
Why FRP composites for seismic rehabilitation?
Seismic vulnerabilities of bridge structures constructed prior to 1970 have become evident following the major earthquakes. This put extra strain on the construction industry to upgrade deficient bridges which comprise a major portion of civil infrastructure in North America. Following are some of the factors that justify the use of FRP composite in bridge rehabilitation applications:
- High strength-to-weight ratio
- High stiffness-to-weight ratio
- The ease of production, handling, and installation of FRP wraps
- Minimal disruption to traffic
- Corrosion resistance of FRP protects the inner reinforcement against further corrosion
- FRPs do not reduce the clear height of a bridge
- Reduced maintenance cost
- The properties of FRP can be tailored for unique applications
The concrete infrastructure has been adversely affected by corrosion and weathering over the past three decades. Highway concrete bridges, in particular, experience premature structural decay as a result of heavy seismic activities and steel reinforcement corrosion. Because of enormous rehabilitation cost, FRP materials are being increasingly used in new bridge applications.
Tuf-Bar is an innovative producer and seller of GFRP fiberglass rebar in North America where we design and manufacture sustainable construction materials that can be used for both new and rehabilitation applications. Our products include fiberglass rebar, concrete anchors, rock bolts, and form ties. Visit our site to explore how advanced composites can help you build durable RC structures.