Loading...

Experimental Study of Lightweight and Normal-Weight Concrete under Impact Loads: The Influence of Prestressing and Fiber Reinforcement

Afshani, Zeinab | 2025

3 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 58777 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Rahimzadeh Rofooei, Fayaz
  7. Abstract:
  8. Given the increasing use of lightweight concrete in the construction industry, particularly in precast elements, evaluating its performance under dynamic loads such as impact is of high importance. This study presents an experimental and numerical investigation into the behavior of slabs made from lightweight and normal-weight concrete under low-velocity impact loads, and evaluates the effectiveness of two strengthening techniques: prestressing and the addition of steel fibers. In the experimental phase, fifteen concrete slabs with identical dimensions were designed and fabricated. The main variables included the concrete type (lightweight and normal-weight), the reinforcement method (conventionally reinforced, prestressed with two different stress levels, and reinforced with steel fibers at two different volume fractions), and the impact energy level (two different drop heights). The specimens were subjected to a drop-weight test, and their dynamic responses, including impact force, slab acceleration and displacement, and rebar strain, were recorded. In the numerical phase, a nonlinear finite element model was developed using LS-DYNA software to simulate the experimental results. The results indicated that, compared to their normal-weight counterparts, lightweight concrete slabs exhibited greater vulnerability to impact, with failure being predominantly local (punching), despite absorbing more energy. In contrast, overall (flexural) failure was dominant in the normal-weight concrete slabs. Both strengthening methods significantly improved the impact performance of the slabs. Prestressing was highly effective in reducing overall (flexural) failure, leading to the greatest reduction in total structural damage. The addition of steel fibers also dramatically prevented local failure and maintained the slab's integrity after impact. Furthermore, the investigation revealed that both strengthening techniques were more effective on lightweight concrete slabs, highlighting their high potential to compensate for the inherent weaknesses of this material. Finally, the developed numerical model showed excellent agreement with the experimental results, and its accuracy and validity for future parametric studies were confirmed. This research demonstrates that prestressing and the addition of steel fibers are effective strategies for enhancing the safety of lightweight concrete structures against impact loads
  9. Keywords:
  10. Concrete Slabs ; Impact Loads ; Prestressing ; Fiber Reinforced Concrete ; Experimental Studies ; Finite Element Modeling ; Light Concrete

 Digital Object List

 Bookmark

No TOC