Characterising the Static and Impact Load Resistance of One-Way RC Slabs Strengthened by NSM CFRP Rods

  • Alaa Al Nussairi

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


This study aims to enhance the blast resistance of reinforced concrete slabs which are commonly encountered in modern buildings. The focus is on preventing their collapse by increasing their ductility and energy dissipation by strengthening them with near surface mounted (NSM) carbon fibre reinforced polymer (CFRP) rods.

Laboratory experiments were conducted to study the entire responses of one-way RC slabs with and without NSM CFRP strengthening with different loading rates (quasi-static and impact load). The quasi-static tests showed that strengthening both faces of the slab contributes to increasing the load capacity and ductility of the slab. In addition, the dissipated energy of the control slab was doubled in the strengthened slab. In the impact tests, the dissipated energy enhanced by a factor of 2.1 when only the compression face of the slab was strengthened by 7 CFRP bars. Also, applying the external strengthening technique led to a change in the crack pattern from one opened crack to multiple cracks in the tension face.

Analytical and numerical models were also provided in this study to simulate the static and impact responses of the one-way NSM CFRP RC slabs. The analytical model was developed by modifying the traditional nonlinear layered analysis to incorporate CFRP bars and the various strain rate values. The modification in the nonlinear layered method comprised deriving and including the effect of the crack patterns on the entire response of the slabs, and combining a single-degree-of-freedom (SDOF) method to estimate the maximum response of the slab under blast and impact loads. The commercial software Abaqus was utilized in the numerical analysis. Results from both these models show a good agreement with the experimental results in terms of the entire load-deflection behaviour for both quasi-static and impact tests.

The developed models were used to investigate the effects of the potential relevant factors on the entire response of the NSM CFRP system. The results show that the dissipated energy achieved by strengthening both faces of the slab depends on the ratio of the strengthening in each face, and the optimum dissipated energy was obtained when the CFRP in the tension face was allowed to rupture by increasing the CFRP strengthening ratio in the compression face if the shear resistance is controlled. The results also showed that the enhancing factor of the energy dissipation was almost strain rate independent.
Date of Award6 Nov 2018
Original languageEnglish
Awarding Institution
  • University of Bristol
SupervisorJitendra Agarwal (Supervisor), John H G Macdonald (Supervisor) & Wendel Sebastian (Supervisor)

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