Experimental Study on the In-situ Stress Measurement of Reinforced Concrete Structure by the Ring-Hole Method with FBG Sensor

Abstract

Reinforced concrete structure is widely used in civil infrastructure engineering. In order to ensure the service safe of those infrastructure, periodic inspection and evaluation is necessary. Stress is an important indicator of existing structural evaluation. How to determine the in-situ stress of reinforced concrete structures is basic work of structural safety assessment, restoration and repair. Currently the accurate in-situ stress of the pre-stressed concrete structures is very difficultly obtained. This paper present a new ring-hole method with FBG sensors to measure the in-situ stress for a reinforced concrete structure, which based on stress release. The depth of ring-hole, the elasticity modulus of core-like concrete and the comparison of different sensors are studied by two reinforced concrete specimen test. The experimental results show that: (1) The method can effectively and accurately measure the in-situ stress of the concrete structure with the maximum relative error being 8.66%; (2) The stress of concrete will be completely released when the drilling hole depth up to 30mm for 100mm diameter; (3) FBG sensor is more stable than the traditional electrical measurement method.