Saeed Ahmari

Constitutive Modeling and Testing of Interface between Backfill Soil and Fiber-Reinforced Polymer

AbstractGeomaterials behave differently under different types of loadings, such as compression, shear, or tension; they exhibit weaker response in tension. To increase the tensile and shear strengths of the soil, different methods of reinforcement, such as geosynthetics, have been used in earth structures such as retaining walls, earth dams, and slopes. The use of geosynthetics has attracted the attention of engineers and researchers in recent years. However, there are some significant problems associated with geosynthetics, such as low tensile strength, creep, and for some applications, a low stiffness modulus. In this research, a geocomposite (GC), made of carbon fiber–reinforced polymer (CFRP), is proposed and studied. The interface properties of the CFRP and backfill soil are investigated experimentally using a cyclic multidegree-of-freedom (CYMDOF) device. Then an elastic–plastic constitutive model, the hierarchical single surface (HISS), is used to characterize the behavior of the interface between ...

Impact location and load identification through inverse analysis with bounded uncertain measurements

The growing demand for real-time damage assessment necessitates development of an efficient inverse analysis algorithm with consideration of practical issues such as uncertainty in measurement. A mathematical model-based inverse analysis scheme is proposed to identify impact locations and reconstruct impact load time history of a simply supported plate through multiple levels of analysis. The proximity of the impact location is first determined by the triangulation method and the impact location is then refined by minimization of an objective function through the particle swarm optimization method (PSO). Loss of data due to filtration is addressed in a further level by performing an interval analysis based on extreme measurement errors. The outcome of the analyses is a mean impact location, a load time history, and a range of likely deviations. The extreme deviation in impact location is shown by bounding lines, which form a rectangle. The deviation in load time history is also shown by upper and lower bounding sinusoidal curves. The results of the analyses indicate that the proposed method can effectively locate the impact point and reconstruct the load time history even with the existence of noise in the measured response.

Strength Evaluation and Energy-Dissipation Behavior of Fiber-Reinforced Polymer Concrete

There is a growing demand in finding a replacement for ordinary Portland cement (OPC) because of inherent weakness in mechanical properties and durability of the OPC. In this study, polymer concrete (PC) is investigated as a potential replacement for OPC-based concrete. PC contains a mixture of epoxy resin and aggregates for which the epoxy resin serves as the cementing agent. Processes of forming PC and FRPC (fiber-reinforced polymer concrete) have been developed and are presented in detail. Behavior of PC and FRPC under compressive, tensile, and impact loadings are determined through experiments. The studies are conducted in three phases with objectives of optimizing the bulk density and strength of the medium. Our experimental results indicate that the PC and FRPC specimens exhibit significantly higher compressive and tensile strength and impact toughness as compared to OPC. However, FRPC specimens have higher tensile strength and toughness relative to PC specimens, but the two sets are comparable in compressive strength. Furthermore, PC, as well as FRPC, have a faster curing rate as compared to OPC (less than 5 days for full curing).

Feasibility Study of Compressed Air Energy Storage using Steel Pipe Piles

Because of the intermittent nature of renewable energy such as solar and wind energy, an energy storage system is needed to maximize the utilization efficiency of renewable energy. Of the different methods for energy storage, compressed air energy storage (CAES) is a promising one for storage of renewable energy. CAES can be divided into two general categories: large scale storage and small scale storage. The large scale storage includes salt caverns, hard rock caverns and deep aquifers, which require special geological formations that may not be available at a desired location. The small scale storage includes flexible bags under water, steel tanks above or below ground surface and pipelines above or below ground surface, which are flexible and can be used at different locations. In this paper, we briefly reviewed the different methods for CAES and studied the feasibility of using steel pipe piles for small scale CAES of renewable energy. The results indicate that steel pipe piles are a viable means for small scale CAES.

The properties and durability of alkali-activated masonry units

Clay bricks and concrete blocks are two widely used masonry units (MU). Because both contain high embodied energy and have large carbon footprint, much research has been conducted on developing sustainable alternatives such as geopolymer masonry units (GMU) for them. This chapter first reviews the production of GMU from different types of wastes and then discusses the physical and mechanical properties and durability of GMU based on different types of wastes. Finally, some suggestions for future work on GMU are presented.

Behavior of polymer concrete beam/pile confined with CFRP sleeves

ABSTRACT This research investigates the flexural behavior of a polymer concrete beam/pile encased with carbon fiber sleeve. The mechanical properties of carbon fiber sleeves in tension and cement and polymer concrete in compression were determined. Polymer concrete beams were tested in flexure to determine the bending moment capacity. Then, the test results were compared to the theoretical model results. Finally, a parametric study was conducted to determine the influence of beam/pile parameters on the capacity of the element. Based on the investigation, carbon fiber sleeve filled with polymer concrete exhibits outstanding structural performance including ductility and bending capacity.

The properties and durability of mine tailings-based geopolymeric masonry blocks

The growing concerns about global warming and diminishing natural resources have led to research on developing innovative methods for producing green and sustainable construction materials. Utilization of mine tailings (MT) to produce geopolymer masonry blocks is a novel way to meet the emerging needs. The major challenge with the utilization of MT as construction material is their reactivity and phase composition, which can be addressed by improving geopolymerization through different methods such as preactivation by heating, addition of highly reactive materials, utilization of appropriate activator and curing temperature, and addition of calcium to the mixture. This chapter describes the physical and mechanical properties of MT-based geopolymer masonry blocks. The durability of MT-based geopolymer in aggressive environments and the effectiveness of immobilization of contaminants in the original MT after geopolymerization are also discussed.