References of "Cai, Gaochuang 50030586"
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See detailProperties and mechanisms of self-sensing carbon nanofibers/epoxy composites for structural health monitoring
Wang, Y.L; Wang, Y.; Wan, B.L et al

in Composite Structures (2018), 200

In this paper, carbon nanofibers (CNFs) with high aspect ratio were dispersed into epoxy matrix via mechanical stirring and ultrasonic treatment to fabricate self-sensing CNFs/epoxy composites. The ... [more ▼]

In this paper, carbon nanofibers (CNFs) with high aspect ratio were dispersed into epoxy matrix via mechanical stirring and ultrasonic treatment to fabricate self-sensing CNFs/epoxy composites. The mechanical, electrical and piezoresistive properties of the nanocomposites filled with different contents of CNFs were investigated. Based on the tunneling conduction and percolation conduction theories, the mechanisms of piezoresistive property of the nanocomposites were also explored. The experimental results show that adding CNFs can effectively enhance the compressive strengths and elastic moduli of the composites. The percolation threshold of the CNFs/epoxy composites is 0.186 vol% according to the modified General Effective Media Equation. Moreover, the stable and sensitive piezoresistive response of CNFs/epoxy composites was observed under monotonic and cyclic loadings. It can be demonstrated that adding CNFs into epoxy-based composites provides an innovative means of self-sensing, and the high sensitivity and stable piezoresistivity endow the CNFs/epoxy composites with considerable potentials as efficient compressive strain sensors for structural health monitoring of civil infrastructures. [less ▲]

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See detailStrain and Damage Self-Sensing of BFRP Laminates Fabricated with CNFs/Epoxy Composites under Tension
Wang, Y.L; Wang, Y.S.; Wan, B.L. et al

in Composites. Part A, Applied Science and Manufacturing (2018)

This study investigated the strain and damage self-sensing capabilities of basalt fiber reinforced polymer (BFRP) laminates fabricated with carbon nanofibers (CNFs)/epoxy composites subjected to tensile ... [more ▼]

This study investigated the strain and damage self-sensing capabilities of basalt fiber reinforced polymer (BFRP) laminates fabricated with carbon nanofibers (CNFs)/epoxy composites subjected to tensile loadings. The conduction mechanisms based on the tunnel conduction and percolation conduction theories as well as the damage evolution were also explored. A compensation circuit with a half-bridge configuration was proposed. The results indicated the resistivity of the CNFs/BFRP laminates and CNFs/epoxy composites exhibited similar change rule, indicating that the conductive networks of CNFs/BFRP laminates were governed by CNFs/epoxy composites. With the increase of strain under monotonic tensile loading, the electrical resistance response could be classified into three stages corresponding to different damage modes. This confirmed CNFs/BFRP laminates have excellent self-sensing abilities to monitor their internal damages. Moreover, stable and repeatable strain self-sensing capacity of the CNFs/BFRP laminates was verified under cyclic tensile loading because the electrical resistance varied synchronously with the applied strain. [less ▲]

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See detailStrain monitoring of concrete components using embedded carbon nanofibers/epoxy sensors
Wang, Y.L.; Wang, Y.S.; Han, B.G. et al

in Construction and Building Materials (2018)

In this study, embedded strain sensors based on the principle of piezoresistivity were fabricated by epoxy-based composites filled with different contents of carbon nanofibers (CNFs). The piezoresistive ... [more ▼]

In this study, embedded strain sensors based on the principle of piezoresistivity were fabricated by epoxy-based composites filled with different contents of carbon nanofibers (CNFs). The piezoresistive performances and relevant parameters including gauge factor, linearity, repeatability and hysteresis of these sensors were investigated. A compensation circuit was proposed to eliminate the influence of temperature on sensing signals of the sensors. The CNFs/epoxy sensors were embedded into concrete cylinders to monitor their compressive strains under monotonic and cyclic loadings, thereby assessing practical applications of the CNFs/epoxy sensors as strain sensors for monitoring concrete structures. The results indicate that the sensors containing 0.58 vol% of CNFs, which have a gauge factor of 37.1, a linearity of 5.5%, a repeatability of 3.8% and a hysteresis of 6.3%, exhibited better piezoresistive performance compared to those containing 0.29 vol% of CNFs. The calibration and monitoring curves exhibited a consistent variation trend when the cylinders embedded with sensors were subjected to monotonic and cyclic loadings. This demonstrates that the CNFs/epoxy sensors have considerable potential to be used as embedded strain sensors for structural health monitoring of concrete structures. [less ▲]

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See detailIn Situ Strain and Damage Monitoring of GFRP Laminates Incorporating Carbon Nanofibers under Tension
Wang, Yanlei; Wang, Y.S.; Han, B.G. et al

in Polymers (2018)

In this study, conductive carbon nanofibers (CNFs) were dispersed into epoxy resin and then infused into glass fiber fabric to fabricate CNF/glass fiber-reinforced polymer (GFRP) laminates. The electrical ... [more ▼]

In this study, conductive carbon nanofibers (CNFs) were dispersed into epoxy resin and then infused into glass fiber fabric to fabricate CNF/glass fiber-reinforced polymer (GFRP) laminates. The electrical resistance and strain of CNF/GFRP laminates were measured simultaneously during tensile loadings to investigate the in situ strain and damage monitoring capability of CNF/GFRP laminates. The damage evolution and conduction mechanisms of the laminates were also presented. The results indicated that the percolation threshold of CNFs content for CNF/GFRP laminates was 0.86 wt % based on a typical power law. The resistance response during monotonic tensile loading could be classified into three stages corresponding to different damage mechanisms, which demonstrated a good ability of in situ damage monitoring of the CNF/GFRP laminates. In addition, the capacity of in situ strain monitoring of the laminates during small strain stages was also confirmed according to the synchronous and reversible resistance responses to strain under constant cyclic tensile loading. Moreover, the analysis of the resistance responses during incremental amplitude cyclic tensile loading with the maximum strain of 1.5% suggested that in situ strain and damage monitoring of the CNF/GFRP laminates were feasible and stable. [less ▲]

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See detailBasic mechanical behaviours and deterioration mechanism of RC beams under chloride-sulphate environment
Wang, J.H; Cai, Gaochuang UL; Wu, Q.

in Construction and Building Materials (2018)

This paper investigates the basic mechanical behaviour of reinforced concrete (RC) beams using chloride corrosion-damaged steel reinforcements and subjected to sulphate ions environment. To this end, ten ... [more ▼]

This paper investigates the basic mechanical behaviour of reinforced concrete (RC) beams using chloride corrosion-damaged steel reinforcements and subjected to sulphate ions environment. To this end, ten RC beams were studied which contained 5% sodium chloride and implemented by a series of drying-immersion cycling (15% sodium sulphate immersion solution). Test results indicated that the flexural capacity, ductility, and stiffness of the beams were improved at early stage of the corrosion. This was attributed to the fact that concrete strength and steel-concrete interfacial bond were enhanced. The former is for the filling effects of micro-expansive Ettringite and gypsum sulphate, while the latter is due to the slight surface corrosion pits of steel bars at the stage. However, the mechanical properties of the beams decreased subsequently for the deteriorations in the concrete strength due to excessive expansion of Ettringite and gypsum sulphate, and the degradation of self-property of reinforcement and its interface bond with the concrete. Based on the study, the deterioration mechanism of RC beams under chloride-sulphate environment was discussed and its main determining factors at different stages were analysed. [less ▲]

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See detailHysteretic behaviour of steel fibre RC coupled shear walls under cyclic loads: Experimental study and modelling
Zhao, J.; Cai, Gaochuang UL; Si Larbi, Amir et al

in Engineering Structures (2018)

This paper presents the hysteretic behaviour of three 1/3-scale three-storey steel fibre reinforced concrete (SFRC) coupled shear walls (CSWs) under cyclic loads. The deformation, ductility, energy ... [more ▼]

This paper presents the hysteretic behaviour of three 1/3-scale three-storey steel fibre reinforced concrete (SFRC) coupled shear walls (CSWs) under cyclic loads. The deformation, ductility, energy dissipation, stiffness and crack propagation of the specimens are also discussed and analysed. The results show steel fibre improves the ductility and energy dissipation capacity, and restrains the crack propagation of the CSWs, and delays the degradation of their lateral stiffness and force. Based on the experiments, a simple trilinear model is developed to simulate the skeleton curve of lateral force–displacement of the SFRC CSWs. Through analysing several typical cycles of the hysteretic of these CSWs, the feature points of the proposed hysteretic model are defined which subsequently is used to evaluate the complete hysteretic behaviour of the CSWs. Using existing experimental data and this study, several representative experimental hysteretic cycles are compared with the proposed model. The result indicates a good agreement is reached between the model and experimental results. [less ▲]

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See detailApplication of Variance Analyses Comparison in Seismic Damage Assessment of Masonry Buildings Using Three Simplified Indexes
Su, Qiwang; Cai, Gaochuang UL; Degee, Herve

in Mathematical Problems in Engineering (2017)

The reasonable assessment of potential damage type of masonry structures in seismic-prone zone is very significant to strengthen existing masonry structures and guide the construction of the new building ... [more ▼]

The reasonable assessment of potential damage type of masonry structures in seismic-prone zone is very significant to strengthen existing masonry structures and guide the construction of the new building. The primary objective of the study is to propose and determine a reasonable assessment index to predict the damage type of masonry structures in different seismic intensity zones using the survey results of the 2008 Wenchuan earthquake and variance analyses comparison methods. Three potential theory assessment indexes are considered in the evaluation of damage of masonry structures, including wall density index , strength index , and combined index . In order to compare the feasibility of the three indexes, One-way analysis of variance and Scheffé’s method were used for in-depth discussion. Based on the proposed assessment indexes, further analyses and recommendations were provided. Results show the combined index has a high potential to predict the damage levels of masonry structures. Based on the study, several recommendations were provided for the masonry structures in seismic-prone zones. [less ▲]

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See detailUltimate strengths of FRC rectangular columns subjected to simulated seismic loading: Experimental database and new models
Cai, Gaochuang UL; Degee, Herve

in Archives of Civil and Mechanical Engineering (2017)

While there are many experimental investigations focusing on seismic behaviour of fibre reinforced concrete (FRC) columns, the studies regarding the accuracies and conservativeness of existing seismic ... [more ▼]

While there are many experimental investigations focusing on seismic behaviour of fibre reinforced concrete (FRC) columns, the studies regarding the accuracies and conservativeness of existing seismic strength models of FRC columns are limited. This paper presents a seismic research database of 322 FRC columns obtained from a comprehensive literature investigation. The characteristic of the database and the effects of main variables on the seismic strengths of FRC columns are analyzed in detail, the accuracies of existing strength models of FRC column are also examined as well. In addition, using the database, considering the effects of fibre and other structural factors on FRC columns, Priestley et al. shear and CFB-FIP moment models are modified respectively. Results show that the two proposed strength models both present better evaluation than other models. On the other hand, a detailed method for assessing the potential failure mode of FRC column subjected to seismic loads is also suggested using the two strength models. The comparative results verify the feasibilities and accuracies of the assessment method in FRC columns. [less ▲]

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See detailDeterioration of Basic Properties of the Materials in FRP-Strengthening RC Structures under Ultraviolet Exposure
Zhao, Jun; Cai, Gaochuang UL; Cui, Lu et al

in Polymers (2017)

This paper presents an experimental study of the basic properties of the main materials found in reinforced concrete (RC) structures strengthened by fibre reinforced polymer (FRP) sheets with scope to ... [more ▼]

This paper presents an experimental study of the basic properties of the main materials found in reinforced concrete (RC) structures strengthened by fibre reinforced polymer (FRP) sheets with scope to investigate the effect of ultraviolet (UV) exposure on the degradation of FRP, resin adhesive materials and concrete. The comparison studies focused on the physical change and mechanical properties of FRP sheet, and resin adhesive materials and concrete before and after UV exposure. However, the degradation mechanisms of the materials under UV exposure were not analyzed. The results show that the ultimate tensile strength and modulus of FRP sheets decrease with UV exposure time and the main degradation of FRP-strengthened RC structures is dependent on the degradation of resin adhesive materials. The increase in the number of FRP layers cannot help to reduce the effect of UV exposure on the performance of these materials. However, it was verified that carbon FRP materials have a relatively stable strength and elastic modulus, and the improvement of the compression strength of concrete was also observed after UV exposure. [less ▲]

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See detailSimplified density indexes of walls and tie-columns for confined masonry buildings in seismic zones
Cai, Gaochuang UL; Su, Q.W; Tsavdaridis, K.D. et al

in Journal of Earthquake Engineering (2017)

This paper discusses and quantifies the minimum requirements of walls and tie-columns in confined masonry (CM) buildings located in earthquake-prone regions. A research database including 238 damaged CM ... [more ▼]

This paper discusses and quantifies the minimum requirements of walls and tie-columns in confined masonry (CM) buildings located in earthquake-prone regions. A research database including 238 damaged CM buildings obtained from the 2008 Wenchuan earthquake survey is established and comprehensively examined. The requirements of masonry walls in CM buildings are discussed, and a simplified tie-column density index is proposed for evaluating the potential damage of the structures. Besides, the minimum requirements of reinforced concrete tie-columns and their maximum allowable spacing in CM buildings at different seismic intensity zones are discussed. [less ▲]

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See detailEffect of Infills on Seismic Performance of Reinforced Concrete Frame structures—A Full-Scale Experimental Study
Cai, Gaochuang UL; Su, Q.W.

in Journal of Earthquake Engineering (2017)

The wall collapse-initiated disaster in infilled reinforced concrete (RC) frame structures has been increasingly concerned by research community recently. This paper studies the seismic performances of a ... [more ▼]

The wall collapse-initiated disaster in infilled reinforced concrete (RC) frame structures has been increasingly concerned by research community recently. This paper studies the seismic performances of a bare RC frame and three RC frames infilled by different lightweight materials in full scale under cyclic loads, including hollow bricks, gypsum blocks, and autoclaved lightweight concrete panels. The main studied performances include lateral resistance capacity, stiffness, wall damage, ductility, and energy dissipation capacity of the frames. Based on the experimental results and literature research, this paper discusses ideal infill materials for RC frame structures and skeleton curve of the frames. [less ▲]

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