The strengthening of reinforced concrete structures using advanced fiber reinforced polymer (FRP) composites is a very popular practice because they are light and highly resistant to corrosion. In particular, the behavior of FRP-reinforced concrete structures is a topic that attracted lot of interest in recent years. However, the application of FRP-reinforced concrete structures requires an extensive development of reliable design equations.This study focuses on the behavior of beams reinforced with different reinforcement ratios of glass fiber reinforced polymer (GFRP) bars and concrete strength. Displacement, strains, and crack width were measured to study the behavior of beams. The results of the investigation can be summarized as follows:(1) Deflections and strains of concrete beams reinforced with GFRP re-bars are generally larger than those reinforced with steel bars; (2) the strength of the concrete has a negligible effect on crack spacing and crack width; (3) and the FRP over-reinforced concrete beams in this study are safe for design in terms of deformability.
This experimental investigation was conducted to examine the behaviour of eight one-third scale columns made of high-strength concrete. The columns were subjected to a constant axial load corresponding to 30% of the column axial load capacity and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research are the volumetric ratio of transverse reinforcement (ρs = 1·58, 2·25%), tie configuration (Type H, Type C, Type D) and tie yield strength (fyh = 548·8 and 779·1 MPa). Test results show that the flexural strength of all the columns exceeds calculated flexural capacities based on the equivalent concrete stress block used in the current design code. Columns with 42% higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-02 showed ductile behaviour. With an axial load of 3% of the axial load capacity, it is recommended that the yield strength of transverse reinforcement be held equal to or below 548·8 MPa. Relationships between the calculated damage index and the observed damage such as initial crack, spalling of concrete, buckling of longitudinal bar, and crushing of concrete are proposed.
The strength of reinforced concrete members may vary from the calculated or the nominal strength due to variations in the material strength and dimensions of the element. Statistical descriptions of the variabilities in loads and strengths are required in all studies pertaining to the safety of reinforced concrete members.Therefore, this paper recommends a number of values for the coefficient of variation of concrete, reinforcement, dimension and load to be used in the probability analysis. Also, this study analyzes reinforced concrete members using the Advanced First Order Second Moment (AFOSM) method using the statistical characterization of variables. This study shows that Bayes' theorem is an effective tool for updating prior probabilities when the value of a random parameter is known. Finally, the results in this paper contribute to the limit state reliabilities implied in the current design of reinforced concrete elements.
Recently the Permanent Uni-wall System (PUS) has been developed which improved the disadvantage of the Cast-In-Place Concrete Pile (CIP) and could be used as permanent retaining wall. In this study, joints between PUS and floor systems were developed. From analyses of the characteristics of design and construction of PUS, shear friction reinforcements with couplers were adopted for shear design of the joints. Twelve types of joints were developed which were classified according to the types of floor structures, wale, and piles of PUS. Two typical joints were tested and the joints showed satisfactory behaviors on the points of shear strength, stiffness, and serviceability. Especially the shear strengths were much higher than the design strengths due to the shear keys which were by-products in splicing shear reinforcements. However, the shear strength of the joint is recommended to be designed by only shear friction reinforcement because shear key is not reliable and too brittle.
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