Advanced Materials Research Vols. 446-449

Abstract: The strength characteristic of discontinuity is one of the most important mechanical characteristics of rock mass, and its strength dominates the strength and deformation of joint rock mass. The underground water has an important influence on the strength of discontinuity. In this paper, the strength theory of joint rock mass was summarized and analyzed; further, two kinds of failure mode of joint rock mass which are joint shear failure and rock shear failure were proof. Considering the impact of underground water, the effective stress principle was introduced, and base on it, the joint shear failure strength rule of the saturated rock mass was built. When the influence of underground water on joint strength is studied, the shear strength formula has important theoretical and realistic significance.

Abstract: In this paper double-layer space grids structure with rectangular shape is assumed as equivalent sandwich plate, and has been analyzed by the non-traditional theory of plate with three generalized displacements, in which shearing deformation is considered. Based upon the split rigidity method, static analysis and natural vibration analysis of double-layer space grids structure has been studied. The formulas for calculating internal forces, displacement as well as fundamental frequency are given out. The comparison with finite element method and equivalent sandwich plate method shows that split rigidity method is not only simpler than other simplified methods but also of high accuracy.

Abstract: Numerical simulation and fracture analysis were performed on conventional joint of H-style beam-square steel tubular column based on suggested elliptical yield model. The modified coefficient of elliptical fracture model was obtained by equivalently calculating the effects of residual stress and flaws. Using the elliptical fracture model with equivalently calculating the effects of residual stress and disfigurement for evaluation, the parameters of slot holes and horizontal haunch at beam flanges on failure mode of joints of H-style steel beam-square steel tubular column were studied by finite element method. The results indicate that the plastic rotation of joints of H-style beam-square steel tubular column with slot holes and horizontal haunch at beam flanges reach 0.03rad and meet with the requirement of the interim guidelines FEMA, and the loading capacity decrease within 15% compared with that of the conventional joint.

Abstract: In this paper the nature of bond stresses are studied for different regions of reinforced concrete elements subjected to flexure and shear, various literature articles on the subject are reviewed and the seismic effect for bond and development length is discussed.

Abstract: Abstract: the cracking of semi-rigid material may be believed for fatigue damage, temperature and dry shinkage, from above the analysis, and based on the disease prevention of the semi-rigid pavement, some treatment measures have been devoted, this study results for the semi-rigid material can provide a better technical support.

Abstract: On the basis of previous experimental research, the nonlinear finite element analysis of the out-of-plane beam-wall joint is made with nonlinear bond-slip constitutive relations between steel and concrete. The force mechanism of concealed beam in the joint is studied in detail, and parametric analysis is carried out for height of concealed beam. Results of experiment and nonlinear analysis proved that: concealed beam is the important guarantee for mechanical behavior of the out-of-plane beam-wall joint. In addition, the torsional capacity and height of concealed beam are the main factors influencing on moment transfer behavior of the joint.

Abstract: This paper produced four frame joints strengthened by self-compacting concrete and one unstrengthened joint for comparison. Take MTS servo loading system of static test for the frame joints under secondary load，to study the influence of different interface treatments for the seimic performance. The interface of the four strengthened joints respectively using roughening and grooving with different grooving density. The results of the damage process, strain of the old steel and new steel, the load -displacement hysteresis loops was analyzed，and it was found that the cooperational performance of the old concrete and new concrete was good when using self-compacting concrete to strengthen the frame joints with the interface treatments roughening and grooving. Considering the impact of the interface treatment, the ultimate strength, displacement, and displacement ductility coefficient of the reinforced joints etc. were slightly increased. And the the more the grooving density was, the better the strengthening effect was, which could be considered in the design of strengthening as its interface treatment.

Abstract: Through the mix ratio optimization test, the appropriate autoclaved aerated concrete block may be prepared for the production demand, whose technical indexes could satisfy the requirement of national specification. Furthermore, in the light of the research on the property of autoclaved aerated concrete block for this mix ratio, the strength of concrete block would decrease with the increase of total porosity among the pore diameter from 0.5mm to 1.5mm. The autoclaved aerated concrete block possessed the strong capability of absorbing water, so the volume water absorption rate increased quickly at first and then went down furiously, which could make the shrinkage of autoclaved aerated concrete block augment because of the decrease of its water absorption rate.

Abstract: By considering the nonlinearity of material and geometric, the finite element analysis is performed for the circular tubular TK-Joints to demonstrate the stress distribution. plastic-zones and deformation of joints is studied on multi-planer XK steel tubular joints through various geometric parameters by using the nonlinear finite element analysis in this paper. The primary parameters and the influence of these parameters on the ultimate strength are investigated. Based on the bearing capacity formula of K- joint and some reference data, the strength formula for multi-planar XK joints is suggested in view of the effects of multi-staff intersection and multi-axis bearing force. These formulas provide the academic basis for construction design.

Abstract: This research was to reveal the influence of cooling water pipe on temperature field in concrete with different numerical methods. The effect of cooling water was simulated by the finite element methods contained the approximate method and the coupling method. The results showed that the temperatures were calculated by approximate method were lower than the results of coupling method, and the largest difference in temperature was 1.52°C. The temperature gradient changed obviously near the water pipe and the effective cooling length of the water pipe along the radial direction was 0.1m. Moreover, the largest temperature error was 3.95％ in the hydration time of 24h, and away from the water pipe 0.2m through compared the results of two methods. The results would be helpful to research the combine water pipe thermal field on concrete, and predict the temperature cracks in the construction engineering.