Advanced Materials Research Vols. 163-167

Abstract: To further understand displacement based seismic theory of building structures, the seismic performance evaluation using capacity spectrum method related to damping is carried out for the reinforced concrete frame-shear wall model structure of a thermal power main plant. By comparing with time-history analysis results, it can be seen that some problems such as equivalence of multi-degree-of-freedom system and value of equivalent damping ratio in capacity spectrum method remains to be further investigated. Force and displacement response of structures and plastic hinges position of all members could be obtained through nonlinear push-over analysis after determining the top displacement; weak parts and damage pattern of structures could also be easily found out by this method. At last, research shows that dynamic time-history analysis can be replaced by static push-over analysis, which is regarded as an exact seismic performance evaluation method by contrast.

Abstract: Reinforced concrete core walls with good anti-side rigidity and spatial rigidity is used widely in high-rise buildings. Elasto-plastic static analysis of core walls are be realized by the program CANNY based on the theory of fiber model. Compared with the tests, Results from the simulation anlysis match well with those from the tests. The influence of axial compression ratio and height-width ratio on the bearing capacity and deformation of core walls are analyzed systemically. It is shown that the fiber model is available and successful for the numerical simulation of core walls. The axial compression ratio has distinct affect on the elastic and inelastic behavior of RC core walls. The ratio of height to width not only has effect on the bearing capacity and deformation performance, but also changes the failure mode of RC core walls. The numerical results confirmed the accuracy of this analysis procedure in representing the nonlinear behavior of core walls.

Abstract: Seismic performance of a kind of superposed wall, which is composed of two precast panels and the cast- in- place core concrete, was studied in the paper. Two groups of superposed wall units with different edge elements were constructed and tested under quasi- static reversed cyclic loading. The strength, stiffness, ductility, energy dissipation and failure modes of the walls under lateral load were investigated, and the influence of different edge elements to the seismic response of the wall panels was discussed. Moreover, numerical simulation analysis was conducted applying multi- spring (MS) model with the finite element analysis procedure CANNY. Results of the inelastic analysis were compared with the experimental ones to validate the reasonability of the numerical model and evaluate the seismic response of superposed walls further.

Abstract: In order to put forward protective measures and reduce the hazards caused by gas explosion events, it is significantly important to analyze the antiblast properties of the slab. According to the precast slab and poured slab that badly damaged in this two accidents, the antiblast ability of the slabs and explosion overpressure were analyzed. The overpressure differs little but the destruction differs much of the two accidents, so effects of some parameters on the the antiblast ability of the slab were calculated based on multigroup models. The results show that, boundary condition is the primary influence factor, the next is thickness, while the influence of reinforcement ratio is comparatively lower. Based on the calculation results, some protective measures were put forward. The analysis methods and conclusions can offer certain reference to the housing protection design and study.

Abstract: According to frame concrete theory, Concrete was composed of mortar matrix, coarse aggregate, and transition zone between mortar matrix and coarse aggregate. Proper particle grading of fine aggregate can not only save cement, but also increase comprehensive properties of mortar matrix. Uniform design method was used to study the relationships between the grading of fine aggregate and workability, and the relationship with mechanic properties of mortar matrix and concrete. Based on fractal theory, the relationship between fractal dimension and modulus of fineness, and the relationship between fractal dimension and n value in Fuller equation were researched. It concluded that grading of fine aggregate affects the workability and mechanic properties of mortar matrix and concrete, significantly. There was a good linear relation between fractal dimension and n value in Fuller Equation, and fratatal dimension decreased with modulus of fineness increasing.

Abstract: Concrete composite bearing wall system is an innovated composite structure system, which is assembled by load-bearing walls, enclosure walls and thermal protection and insulation layers. Four concrete composite bearing walls were tested quasi-statically under low cyclic lateral loads. The characteristics including failure modes, hysteretic characteristics, ductility and stiffness degradation are investigated. It is shown that the concrete composite bearing walls possess high strength and ductility. In the elastic stage, the prefabricated slabs and frame could work together very well, and the composite walls exhibited enough stiffness against lateral deformation. With increasing horizontal load, the stiffness of the prefabricated slabs tended to decrease, and finally the composite wall system failed by flexural failure of frame structure with dense columns.

Abstract: Rutting is one of the major damage modes in asphalt pavement. Many management departments need to conduct a reasonable assessment of rutting and damage cause analysis to roads. We often use on-site observed means for assessment of road surface rutting. We use methods of on-site core and cutting specimens for laboratory analysis. This paper tell this method of determining the reasons for rutting damage by analyzing the porosity, sub-layer uplift factor, size distribution, whetstone ratio and rutting test results.

Abstract: Diagrid tube structures have advantages on constructing high-rise buildings for its great lateral stiffness, but its seismic design methodology researches are limited. The two-stage design method in Chinese code is not specific enough for the seismic fortification objectives of this kind of structures. It is necessary to propose some specific seismic performance objectives for the key components. Typical CFST diagrid tube-concrete core tube structures are studied by dynamic elastic-plastic time-history analysis using Perform-3D program. The structure plasticity developing process is summarized and the distribution characteristics of seismic fortification lines between tubes are discussed. The influences of main structure lateral stiffness related factors on the plasticity developing process are researched. The key components of structure lateral stiffness and plastic energy dissipation are studied. The seismic performance objectives of the key components are proposed for the three-level seismic fortification objectives.

Abstract: Cracks of concrete structure easily appear in the period of construction and the difference between the inside and outside temperature at early stage and the basic difference of the temperature at later stage are considered as the main factors causing cracks, so the temperature control becomes the key of problem. In view of this problem, this paper puts forward the pipe cooling technology which is usually used in the mass concrete to the thin-walled concrete structure. Under the basic theories of concrete temperature field and numerical algorithm of pipe cooling, the 3-D FEM is adopted to simulate the thermal field of concrete sluice with and without cooling pipe during construction. The results of comparison show that cooling pipe in thin-walled concrete structure can achieve better effect on temperature control, so it should have great reference signification to similar concrete projects in the future.

Abstract: The finite element model of the reinforced beam was established. The results were obtained, such as the structural distortion diagram, the cleavage process diagram, the deflection contour map, the stress contour map to the X axle and the equivalent stress map. The result of the simulation shows that the established reinforced beam bring plastic strain and appear crack under the uniform pressure.