Acoustic Inspection of Coated Steel Bar in Reinforced Concrete Structure

Bridges with reinforcement corrosion problems are now under careful inspection in Taiwan. Costly maintenance programs are underway and raising serious safety concern. There are various engineering solutions to salt-induced corrosion. Among them epoxy-coated reinforcing bars, commonly referred to as rebar, are frequently used in marine environment and other areas due to its durability, reasonable cost, and convenience. However, coated rebar has lower bond strength and is less ductile than uncoated rebar. Thus it could result in larger crack width during pull-out tests [1,2]. The bond strength between coated steel bars and covered concrete results from the adhesion at the steel-concrete boundary, the factional force, and the interlocking force provided by the raised ribs at the steel bar surface. The interlocking force is much stronger than the other two, while the factional force occurs only if the adhesion vanishes after delamination or disbonding starts

A Critical Review on the Structural Health Monitoring Methods of the Composite Wind Turbine Blades

With increasing turbine size, monitoring of blades becomes increasingly im-portant, in order to prevent catastrophic damages and unnecessary mainte-nance, minimize the downtime and labor cost and improving the safety is-sues and reliability. The present work provides a review and classification of various structural health monitoring (SHM) methods as strain measurement utilizing optical fiber sensors and Fiber Bragg Gratings (FBG’s), active/ pas-sive acoustic emission method, vibration‒based method, thermal imaging method and ultrasonic methods, based on the recent investigations and prom-ising novel techniques. Since accuracy, comprehensiveness and cost-effectiveness are the fundamental parameters in selecting the SHM method, a systematically summarized investigation encompassing methods capabilities/ limitations and sensors types, is needed. Furthermore, the damages which are included in the present work are fiber breakage, matrix cracking, delamina-tion, fiber debonding, crack opening at leading/ trailing edge and ice accre-tion. Taking into account the types of the sensors relevant to different SHM methods, the advantages/ capabilities and disadvantages/ limitations of repre-sented methods are nominated and analyzed

Reinforced and Prestressed Concrete Using HPFRCC Matrices

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/84685/1/naaman_HPFRCC2_96.pd