Abstract Purpose. This study aims to evaluate the slope stability of open pit comprising massive and jointed rock mass. Methods. Mohr-Coulomb yield function (MC) with shear strength reduction technique (SSRT) are incorporated in finite element analysis (FEA) and four different slopes with varying geometry and geological structural features with an ultimate slope angle of 34° are analyzed using the two-dimensional FEA Program RS2D. The first slope comprises blocky rock mass; the second slope has a network of joints parallel to slope face; the third slope has a parallel joint networks dip out the slope face, and the last slope has a cross-joints network. Findings. The critical strength reduction factor (CSRF) indicates whether the slope face is stable (if CSRF ≥ 1) or not. The minimum CSRF of 0.53 (e.g. compared to 0.55 for parallel joints dip out to the slope face, 0.58 for joints parallel to slope face and 0.65 with no joint existed) is obtained with cross-joints network existed. The CSRF (e.g., CSRF = 0.49) reduces when the MC slip criterion is adopted with the jointed rock mass. Originality. This study attempts new stability indicator namely critical strength reduction factor (CSRF) embedded in shear strength reduction technique (SSRT), based on finite element (FEM) to assess the slope of open pit with respect to presence of geological discontinuities. Practical implications. The slope stability of rock mass is significant to design parameters in open pit mines. Unexpected instability is eventually costly, hazardous to personnel/machinery, disrupted to the mining operation and time-consuming. Therefore, this study Provides a methodology for the application of shear strength reduction technique (SSRT) when evaluating the slope stability of open pit mines with respect to existence of geological features. As a result, the mine planners and engineers will be able to know a head of time when and where necessary support is needed.

This paper presents a three-dimensional Finite Element Analysis (3D FEA) on reinforced concrete beams tested experimentally by other researcher for investigating the effectiveness of hybrid reinforcement (FRP bars and steel bars) as a main reinforcement to enhance the flexural behavior of concrete beams. To provide a new model which can simulate the performance of concrete beam reinforced with steel and FRP bars accurately, all of the beam components were included in the model and element which composing the model and mesh size were chosen carefully. The user-programmable features in ANSYS 13.0 were used for model analysis. The developed model showed a good agreement with the corresponding experimental result. A parametric study is carried out to investigate the influence of FRP to steel reinforcement ratio, FRP bars type, Location of FRP and steel bars and concrete strength in the behavior of hybrid FRP-RC beams.

Because of the shortcomings of the externally bonded system that mainly consists of epoxy and FRP sheets, the fabric-reinforced cementitious matrix, (FRCM) represents a viable solution in the strengthening of reinforced concrete beams. The FRCM layers consist of fabric mesh embedded in an inorganic stabilized cementitious mortar. Many experimental studies examined the impact of strengthening of RC beams with the FRCM layers, but the numerical investigations are limited. This study is therefore aimed at introducing a numerical study investigating the behavior of RC beams reinforced with FRCM layer. The main goal of this paper is to verify the FEM results with the experimental results that are available in the previous study [1], and to provide a parametric study. The investigated beams in this paper are 150 mm × 250 mm× 3000 mm with two reinforcement ratios. One, two, and three-layers of PBO, (P-Phenylene Benzobis Oxazole) FRCM were investigated as strengthening of the simulated beams were strengthened with. The numerical validation included load-deflection curve, load –strain of both concrete and PBO- FRCM, strain distribution, cracks series and failure mode. The built model gave an accurately prediction of the attitude of the investigated beams. The results also indicated that the rise in the reinforcement ratio or the amount of FRCM layers contributed to improving behavior under both ultimate and serviceability limit states.

A literature fast survey shows that the topic of strengthening concrete columns with fiber-reinforced polymer (FRP) composites has not been sufficiently covered in the available textbooks. Most of the previously published textbooks, which discussed the FRP-confined or strengthened concrete columns (see Fig. 6.1), focused on the behavior and design of circular cross-sections under concentric or eccentric axial loading. The majority of the textbooks focused on confined plain concrete columns. To the best of the author’s knowledge, none of the published textbooks sufficiently studied the available stress–strain models that describe the behavior of the FRP-confined concrete. This chapter presents the following additional contributions to the existing published textbooks about FRP composites as external reinforcements for reinforced concrete (RC) columns: (1) a comprehensive discussion on the stress–strain behavior and modeling of FRP-confined concrete circular and rectangular/square cross-columns, (2) enhancing the ductility of the RC columns using external FRP jacketing, (3) effects of exposure to short and long-term environmental conditions on the behavior of FRP composites used to strengthen the existing columns, (4) ductility design methods of FRP-confined RC columns, and (5) evaluation of the performance of FRP-confined columns considering a damage-controllable mechanical model proposed for the FRP-RC structures.

Fiber-reinforced polymer (FRP) sheets have been increasingly used to reinforce and repair tunnel linings and the slabs of viaducts owing to their advantages. In these FRP-strengthened structures, both in-plane shear stress and out-of-plane normal stress are imposed on the interface between the FRP sheets and concrete. Concrete spalls from the concrete surface owing to different failure mechanisms. To study the bonding and debonding mechanism behind spalling failure, a punching–peeling test against the spalling of concrete pieces is an important tool. In this chapter, the peeling behavior and the spalling resistance of FRP sheets externally bonded to concrete plates and beams are introduced, based on available experimental and analytical investigations. An extremely useful analytical technique for this problem is also introduced in this chapter.

One of the major strengthening applications of fiber-reinforced polymer (FRP) composites is as additional web reinforcement (of various forms) for enhancing the shear resistance of reinforced concrete (RC) beams. Because linear FRP differs from nonlinear steel reinforcement, the design theory of FRP-strengthened RC members exhibits unique characteristics, particularly for shear capacity design. Research on FRP shear strengthening has been limited compared to that on FRP flexural strengthening of RC beams. Nonetheless, the substantial available research has established a general understanding of structural behavior and has inspired several strength models, which are based on experimental observations and the corresponding theoretical assumptions. In this chapter, a comprehensive review of existing shear and torsional strength models is presented. In addition, different failure mechanisms and factors influencing strengthening performance are presented briefly using finite element modeling. A prediction model of shear capacity developed based on numerical analyses is also proposed.

Using fiber-reinforced polymer (FRP) composites to increase the flexural strength of existing structures has gained wide acceptance in recent years. Using high-strength and high-quality adhesives, FRP laminates are externally bonded to the structure that has to be strengthened. Many experimental investigations and practical applications have been performed, thereby demonstrating that the strengthening effects can be reflected in a wide range of aspects, such as the enhancement of the structural stiffness, load-carrying capacity, ductility, and corrosion resistance. In this chapter, a clear understanding of the different failure mechanisms and influencing factors on the flexural performance of FRP-strengthened structures under monotonic and fatigue loads is developed. Based on a series of in-depth studies on the flexural performance of FRP-strengthened concrete structures, a rational methodology is established for the flexural design of FRP-strengthened concrete structures. Some attempts are also made to enhance the structural performance for FRP flexural strengthening. In addition, a series of special field applications for typical FRP flexural strengthening are introduced.

The constituent materials of fiber-reinforced polymer (FRP) composites include resins (matrix materials) and fibers (reinforcing materials). The fibers in the FRP composites may consist of carbon, aramid, glass, basalt, poly-p-phenylene-benzobisoxazole, or other types of polyethylene fibers. This chapter presents a comprehensive review of the basic mechanical properties and behaviors (e.g., tensile strength, stiffness, and strain capacity) of different types of continuous FRP sheets, based on the standard tensile test method. Moreover, the enhancement of their mechanical properties by adopting the concept of hybridization is also addressed. In addition, the effects of environmental conditions, such as low or high temperatures and freezing and thawing cycles, on the mechanical properties of FRP composites are analyzed and discussed. Furthermore, time-dependent behaviors, such as fatigue and creep behaviors, are comprehensively evaluated. Finally, the FRP bonding technique for concrete and steel structures, their installation procedure, and strengthening strategy are briefly described.

In this chapter, the uniaxial tensile tests of fiber-reinforced polymer (FRP)-strengthened tensile members are introduced to explain the tension stiffening effect. Based on experimental observations, an analytical method considering bond stress–slip relationships for steel bar and continuous fiber sheets (or FRP sheets) is presented.

External bonding of fiber-reinforced polymer (FRP) laminates (plates or sheets) for strengthening or retrofitting concrete structures is a bond-critical application. In FRP bonding systems, the performance of the FRP–concrete or steel interface in providing an effective stress transfer is crucial. The attachment of FRP laminates to a concrete substrate can result in interfacial failure modes apart from the conventional flexural failure. In addition, these shifts in failure modes can alter the strength and ductility of the strengthened system. Therefore the fracture theory is introduced in this chapter to discuss the FRP–concrete interface properties. Several studies have presented various failure modes observed in retrofitted civil-engineering structures. Among these, the crack-induced debonding failure mode is the most common in FRP flexural or shear-strengthened concrete members. This is extremely important in the strengthening of concrete members with externally bonded FRP laminates. According to interfacial stress analysis, the interfacial problem may be idealized and studied as an FRP–concrete joint with FRP laminates bonded to the concrete surface and subjected to tension. In this chapter, the bond behavior of similar idealized FRP–concrete joints and design proposals for similar joints are discussed comprehensively.