For a reliable and efficient design of fiber reinforced polymer (FRP) wrapping reinforcement, an accurate stress–strain prediction of reinforced concrete (RC) columns confined with FRP composites is essential. The stress–strain characteristics of FRP-confined concrete have been extensively studied, testing small-scale cylindrical specimens. In this paper, the stress–strain response of axially loaded large-scale columns confined with FRP wrapping reinforcement is investigated. The effective circumferential FRP failure strain and the effect of increasing confining action on the stress–strain behavior of RC columns confined with FRP are examined. Different models for the prediction of the stress–strain behavior of FRP-confined concrete have been reviewed. The existing stress–strain models are applied to predict the stress–strain response of the experimental results presented in this study. A comparison between the experimental results and those predicted by the existing models are presented. Few of the avail...

The comparatively weak performance of fiber-reinforced polymer (FRP) strengthened members under fire exposure is a primary factor hindering the application of FRP strengthening in buildings in which fire risk is not negligible. As part of a larger ongoing study investigating the behavior of FRP strengthening systems under fire exposure, an investigation was set up to examine and document the performance of six full-scale near-surface mounted (NSM) FRP-reinforced concrete beams exposed to 1 h of fire. All the specimens were preloaded to the service load of the strengthened member. Tests results indicated that, if appropriately insulated, the NSM FRP-strengthened beams can achieve a satisfactory fire endurance of 1 h as per fire resistance test specifications. Moreover, this paper also presents a study on the residual performance of fire-tested beams. Results of this study suggest that if the insulation system is able to maintain the adhesive temperature at relatively low value (tadhesive≤1.6tg for ...

The use of optical fiber sensors for monitoring civil engineering structures is increasing continuously. One of the most frequently applied sensor types is the so-called Bragg sensor, which is primarily used to measure structural deformations. Due to some inherent advantages these sensors are ideally suited for long-term monitoring purposes. This paper describes the development of a load cell, based on Bragg sensors, to measure the forces in the ground anchors of a quay wall. After a short introduction on structural monitoring and the principles of a Bragg sensor, the concept of the load cell is discussed. Three ground anchors of a quay wall in Evergem, Belgium have been instrumented. After calibration in the laboratory, the load cells have been used to measure the prestressing forces imposed on the anchors. The results show that the developed instrumentation is very well suited for this purpose. For more than one year, the anchor forces have been monitored at regular points in time. This indicates a depe...

Leakage in underground structures, especially tunnels, may cause seepage erosion in the surrounding soil, which in turn leads to ground subsidence, posing a great threat to urban safety. The current literature mainly focuses on seepage erosion in the sand but lacks a systematic study on the development process of seepage erosion induced by tunnel leakage in different strata. To investigate the different seepage erosion modes induced by tunnel leakage in different stratum types, a series of reduced-scale model tests were carried out. A coupled fluid–solid numerical model was further established to analyze the fine-scale characteristics of different seepage erosion modes. The results show that (1) the soil seepage erosion modes can be divided into three categories: no soil cave, unstable soil cave, and stable soil cave; (2) the adopted coupled fluid–solid numerical model based on DEM, which takes into account the degradation of clay during seepage erosion, can effectively simulate the erosion process of soil with different seepage erosion modes; (3) the phenomena of the three erosion modes are different in the process of erosion development; and (4) the micro-mechanisms of the three seepage erosion modes are different, which are manifested in the erosion range, soil arching effect, and displacement.