The stiffness and strength degradation of timber concrete composite slab deck under repeated loading

• Main Author: Yeo, Kevin Jit Tong
• Format: Thesis
• Language: English; English; English
• Published: 2021
• Subjects: T Technology (General); TA401-492 Materials of engineering and construction. Mechanics of materials
• Online Access: http://eprints.uthm.edu.my/6440/1/24p%20KEVIN%20YEO%20JIT%20TONG.pdf; http://eprints.uthm.edu.my/6440/2/KEVIN%20YEO%20JIT%20TONG%20COPYRIGHT%20DECLARATION.pdf; http://eprints.uthm.edu.my/6440/3/KEVIN%20YEO%20JIT%20TONG%20WATERMARK.pdf; http://eprints.uthm.edu.my/6440/

TCC (timber-concrete composite) is usually utilised in bridges and flooring system where they are subjected to repeated loadings during their service life, which amplifies the occurrence of fatigue. The American Society of Civil Engineers (ASCE) committee on Fatigue Fracture and Reliability states that fatigue is related to about 80 percent of structural failures among bridges. The occurrence of fatigue produces a damaging effect on the concrete, timber, and interlayer shear connectors, which ultimately causes the degradation of strength and softening of the TCC structure. However, there is still limited information available on the fatigue behaviour of TCC structures especially its effect at SLS (serviceability-limit state) and ULS (ultimatelimit state). This research was conducted to observe the fatigue behaviour of TCC structural pedestrian bridges or flooring system, in terms of stiffness and strength degradation by applying repeated loadings to the TCC specimens since the TCC is not a homogeneous structure. The research also included testing the strength properties of the Malaysian tropical timber, (Koompasiamalaccensis), which was utilised for the timber component of the TCC specimens, according to the ASTM D198 standard procedures. From this research, no significant changes of the effective stiffness and connection stiffness were observed when the TCC structures were subjected to repeated loadings at SLS (low amplitude) but the degradation process occurred instantaneously when the TCC structures were subjected to repeated loading at ULS (high amplitude). This is because the timber component, concrete component and shear connectors all have varying maximum load capacity and the repeated loading at ULS is very close to the failure load of the concrete component and shear connectors. The generated S-N graph, strain profile and post-mortem analysis provide a summarisation and explanation of the fatigue life behaviour of the TCC specimens while the Finite Element Modelling (FEM) validates the experimental results.