Papers by Keyword: Reinforced Concrete (RC)

Abstract: An innovative approach to the material science has demonstrated that photocatalytic activity may be conferred to cement-based construction materials, such as concrete, mortars, paints, etc. Photocatalyst is needed for a cleaner environment and a better quality of life that leads to thoughts of a more eco-compatable use of light. Addition of photocatalytic materials to the RC structure during its construction phase could reduce the corrosion problem of RC materials. This material hinders calcium oxide to form acidic compound. In this study, cement-based mixed photocatalytic material has been presented, which would adjustable with RC material for enhancing oxidization process and reducing corrosion problem.

Abstract: In order to research the calculation method of shear capacity for fire-damaged reinforced concrete (RC) beams, the reason of drop of shear capacity was analyzed from material properties and transfer mechanisms of RC beams after fire. Formulas of shear capacity were suggested for fire-damaged RC beams. Based on test analysis, the values of reduction factors of shear capacity were proposed under concentrated load. The results show that suggested calculation method is capable of predicting shear capacity of fire-damaged RC beams exactly. The values of reduction factors of shear capacity need further experiments research.

Abstract: A finite element model for square reinforced concrete stub column under overall fire and axial compression is developed. The temperature of columns subjected to simulated heating and cooling standard fire and the maximal temperature field were determined. The creep of steel bars, bond slip between steel bars and concrete, transformation of material properties were considered in the force analysis. The deformation under overall fire and the load bearing capacity of the column with initial load after fire are provided.

Abstract: In this paper the theoretical model of reinforced concrete frame structure is established to numerically simulate and analyze its overall morphology with the finite element analysis method. The calculation results shows that at the bottom of the structure the stress and deformation is much larger than other parts with the action of constant load, live load and wind load. And with modal analysis and buckling analysis natural frequency and vibration mode are obtained to avoid resonance and predict the buckling load.

Abstract: In order to obtain shrinkage and creep of HPC used in Sutong continuous rigid-frame bridge, shrinkage and creep of plain concrete and RC are investigated under natural environment over two years. Reinforcement ratio 0.76% is close to that of the middle span. Loading stress of creep test is about 15MPa, which is near the maximum stress of the bridge. Four loading ages, 7d, 14d, 21d and 28d, were used to simulate different loading ages in construction. The curves of creep and shrinkage were fitted from test values. The results show the test values of creep and shrinkage were less than the current Chinese bridge code JTG D62-2004, and the creep and shrinkage of RC is less than plain concrete. If the reinforcement ratio is low, reinforcement exerts less influence on creep and shrinkage, and the influence of reinforcement can be neglected in engineering application. Reinforcement can effectively reduce creep and shrinkage if the reinforcement ratio is high.

Abstract: Frame connections imminently need to be strengthened for deficient seismic-resistance in early time. The paper presents research results of strengthening connections through concrete jacketing, bonding steel plate, prestressing, wrapped steel and FRP by scholars in home and abroad, contrasts their strengthening effect and gives the future research aspect.

Abstract: In order to study the influence of the crack-depth ratio on reinforced concrete fracture parameters and the resistance of the reinforcing bar to crack propagation in concrete, the fracture tests were carried on by using four groups three-point bending specimens with initial crack-depth ratios of 0.2, 0.3, 0.4 and 0.5 in this paper. An analytical model was presented to calculate fracture toughness of reinforced concrete by analyzing crack propagation process of the three-point bending beams. The formula of calculating effective crack length of reinforced concrete was established. The research results show that the double-K criterion can be used for describing crack propagation process of reinforced concrete by introducing fracture toughness, which is suitable for reinforced concrete. Initiation fracture toughness and unstable fracture toughness of reinforced concrete slowly increase with the increase of crack-depth ratio, which is different from the properties of ordinary concrete. The reinforced can improve the ductility of concrete obviously and inhibit the rate of crack propagation well.

Abstract: In this paper, the writer analyzed a three-ply reinforced concrete frame structure with specially shaped columns through compiling a program by finite elements program of ANSYS. The results of simulated approached to experimental dates by comparison them. Which mean that use ANSYS program simulated ductility performance of reinforced concrete frame structure with specially shaped columns under reversed cyclic load is feasible. The simulation reflected the ductility of reinforced concrete frame structure, in which from load-on till destruction is perfectly.

Abstract: The aim of the work is to investigate the method of modeling of the UWB GPR for reinforced concrete quality test. Several very important techniques which are ideal for UWB GPR, such as Higher-Order Finite-Difference Time-Domain (HOFDTD), absorbing boundary conditions of Convolution Perfectly Matched Layer (CPML), SGS, signal of pulse train modulated by pseudo random codes and etc. are discussed. Numerical experimental results clearly show that the methods described in this article is much better than traditional ones, and prospecting depth and horizontal vertical resolution of the UWB GPR based on the techniques above all are superior to that of normal GPR. It must receive very good results to use the UWB GPR for reinforced concrete quality inspection in projects.

Abstract: In this study, a push down analysis was performed for reinforced concrete (RC) frame building with collapsed column at lower floor by shock due to abnormal load in order to find progressive collapse process of building. The nonlinear flexural behavior of each structural element was defined from sectional analysis by using X-tract program. For push-down analysis of frame structure, Zeus-NL program was used. Main parameters in the analysis are location of damaged column and story of building. As a result, the deflection at the time of collapse of internal column was lower than one at the time of collapse of external column. In the frame structure with severely damaged column at lower floor, the higher the story was, the smaller the change of moment in beams at upper floors was. And, deflections of beams were found to appear evenly. This can be judged to be caused by a beam's suspension action.