Advanced Materials Research Vols. 255-260

Abstract: Four steel-to-concrete connections with adhesive anchor groups under reversed cyclic loading have been tested. The results showed that anchor steel could reach yield strength before connection failure, generating small shell-shaped concrete cone in the surface of block and the ultimate capacity was governed by strength of anchor. Seismic characteristics of hysteresis curve, rigidity regression, ductility and energy-dissipation were used to draw conclusions that the connections would behave in a ductile manner without significant loss of loading capacity after peak value and visible deformation could develop until failure occurred. Increased embedment depth and added amount of anchors were helpful to improve seismic performance of connections. Only the outer row of most stressed anchors in the tension zone were needed to meet the elliptical interaction of tension and shear capacity requirement during the design process of anchor groups under combined shear and moment loading. In seismic design of steel-to-concrete connections, the predicted capacity by a reduction factor of 0.8 was advised and the comparison of calculated versus observed capacity presented limited variance.

Abstract: The paper proposed design proposal that is combination of solar energy with water source heat pump for heating in the winter at the climate features of the Northwest,And analyzes Major problems and Energy saving property in the use of solar and heat pump design. In the northwest region,there are abundant solar energy resources ,the study will has very important significance to ease the energy shortage and t use renewable energy .

Abstract: This paper presents the utility of Artificial Neural Networks and Regression analysis for the stream flow modeling in Swat River at five discharge gauge station. As an appropriate intelligent model is identified, Artificial Neural Networks (ANNs) is evaluated by comparing it to regression analysis and the available field data. ANNs namely feed forward back propagation neural network (FFBPNN) and regression analysis are introduced and implemented. The research study successfully compared the performance of the ANN and regression models that validated the utility of the two modeling techniques as effective applications to stream flow forecasting.

Abstract: In this paper, improvement of mechanical properties of unreinforced masonry walls based on the laboratory test results is discussed. Various masonry specimens have been tested by Portable Structural Testing Equipment (PSTE). Masonry prisms have been reinforced with indigenous materials (wire mesh and bamboo) and confined with reinforced concrete elements. The tensile strength, shear strength and lateral resistance of masonry walls increases up to 5.4, 2.73 and 5.65 times respectively by using plaster, wire mesh, bamboo and confinement. The Indigenous materials used in this research work are cheap and easily available as compared to FRP and other materials. Analysis for lateral resistance of masonry walls has been made by using different relationships.

Abstract: This paper presents the shake table test of a one-forth scaled model, representing a typical Pakistani three stories confined brick masonry building. The model was constructed following complete model similitude and subjected to a series of sinusoidal base motions of increasing amplitude at a constant frequency equivalent to the predominant frequency of JMA Kobe-1995 earthquake record. The dynamic test data was processed and analyzed to generate the force-deformation curve, ductility ratio and response modification factor of the system. A shear-dominated failure mode was observed. As expected, the ground storey was found to suffer more damage than the other two stories. Out-of-plane failure of walls and crushing of concrete in confining elements were also noted in the final test runs. Based on the damage mechanism and force-deformation characteristics, various performance levels are suggested.

Abstract: A total of 32 circular-section concrete columns confined by CFRP sheet were tested in uniaxial compression involved in different preload ratio, concrete strength and CFRP plies. The failure characteristic and mechanics behavior of confined concrete columns were presented, and the descending of the peak stress and strain of confined concrete due to preload were analyzed. The experimental results indicated that the confinement effect of CFRP was influenced by preload ratio observably. The second stiffness, the peak stress and strain declined with preload ratio ascending, and the extent developed with the enhancement of CFRP ply.

Abstract: The damages to reinforced concrete structures subjected high temperature of fire mainly include the followings: high temperature make the microstructure of concrete be loose and porous, the strength of concrete and steel reduce greatly.The alkaline hydration products of cement was decomposed under the high temperature, which would destroy the alkaline environment of concrete around steel and cause the steel corrosion. In this paper, the machanism of realkalization technique is present. Moreover, method of mercury intrusion pore measurement, SEM analysis and investigation on pH Value of concrete pore solutions experiment were carried out to study the durability repairing efficiency of realkalization technique.

Abstract: The multi-story masonry buildings with reinforced concrete frames on ground floors collapse more easily than pure frames when bottom frames exposed to fire, for reasons that fire load of its ground floors is relatively large, and the ratio of dead load to the total loads is also large, deformations of joists caused by fire produce adverse effect on arch mechanism of masonry. For the purpose of loading temperature on steel bars and concrete for fire resistance analysis of reinforced concrete structures in ABAQUS, separated loading method is proposed firstly in this article. The Hill yield criterion for compression and the Rankine yield criterion for tension are adopted to establish anisotropic elasto-plastic material model for masonry. The process simulation from temperature rises to buildings collapse is realized. A parametric study is conducted to investigate the effects on fire resistance of the bottom frames when the bottom floors exposed to fire due to the change in effective load ratio, section size and reinforcement ratio. The study shows that the failure mode of the bottom frames exposed to fire is mainly due to columns collapse. Bottom fames designed with seismic class I and II have relatively more safety storage than non-seismic designed bottom frames to resist the fire load effect, and they can satisfy time limits of fire resistance.

Abstract: With the development of commercial concrete, the problem of crack has become a difficulty puzzling the engineers. From the view of design ,this paper discussed specially on the problem of residential building’s crack, analysed some faulty and incomplete acts which will cause cracks ,and presented some corresponding control measures.

Abstract: The focus of this study is to analyse the stress distribution of corrugated web girder subjected to out-plane bending. Welded joining is considered in this study to connect the corrugated web and beam flange. As stress concentration is very critical for the prediction of fatigue life of the structure, this study provides preliminary results for further fatigue assessment of box-section girder bridge with such structural details. A finite element analysis based study has been conducted to trace the stress distribution along the corrugated web with varying thickness and cope hole details. The comparison with related simplified expression and typical stress concentration behaviours are outlined in this paper. Comments are given for the further consideration of presented stress characteristics in the fatigue design.