Advanced Materials Research Vols. 368-373

Abstract: Proceeding eigenvalue buckling analysis and geometric nonlinear analysis on schwedler single-layer ellipsoid reticulated shell with analysis software ANSYS, obtain structural buckling mode and ultimate bearing capacity at different short span and different rise-span ratio. Then analyze its impact on static stability of ellipsoid reticulated shell considering load asymmetric distribution and initial defect, conclude stability regular of schwedler single-layer ellipsoid reticulated shell. These study results can provide theoretical basis and technical reference for further studying on static stability of schwedler single-layer ellipsoid reticulated shell and engineering practice.

Abstract: Mechanical analysis for jointed rock mass is very significant in geotechnical engineering. In particular, the mechanical characteristics of jointed rock mass can result in nonlinear response of geotechnical engineering and in consequence mechanical analysis for the engineering is difficult. In order to simulate jointed rock mass, a new equivalent model is proposed for two-dimensional jointed rock mass based on strain energy equivalence principle. Firstly, the equivalent elastic modulus and Poisson's ratio for a horizontal joint in unit square is deduced. Then, the equivalent flexibility matrix for a joint of specified angle in unit square is given. Moreover, the equivalent flexibility matrix for multiple joints, which have different angles in unit square, is obtained. Finally, a numerical simulation is given to verify the model. Compared with other conventional algorithm, the proposed approach has some strong points: it is easy to implement in the finite element program. Furthermore, it provides a new model to compute the deformation of joints and rock and the precision is high.

Abstract: Through the analysis of the collapse reasons of a large steel silo, results show that the main reasons for causing this accident are the design factors, containing horizontal pressure calculation, loads combination, critical stability stress calculation and so on. Temperature stress, storage mode and discharge method, initial imperfections of steel silos are the subordinate reasons and can not be ignored.

Abstract: Characteristics of RCC concrete with greater proportion of magnesium oxide style in domestic are few mentioned, urgently awaits to further study. Through the test of additive magnesium oxide roller compacted concrete's characteristics, to determine the appropriate magnesium oxide style admixture of roller compacted concrete; Accurately calculation the temperature field and stress field of the simulation, the results show the mixed magnesium oxide technology and bury HDPE cooling water pipes measures combining to RCC construction of high-temperature cracking is an effective method of temperature control and crack prevention. It is for the high-temperature environment of RCC dam construction scheme has provided important scientific basis.

Abstract: The cylinder is prone to be damaged due to temperature increasing in vibration control and durability testing process of viscous damper. In order to avoid the overheating generated by long working hours, which resulting in a viscous liquid water evaporation and leading to a abrupt increase in internal pressure inside the cylinder, the CFD software Fluent was used to simulate the durability test process of the oil film, where the heat was easy to generate and suggestion for improving the viscous damper was proposed.

Abstract: In order to study the collapse behaviors due to base sliding of Chinese ancient timber buildings, a simplified model was constructed. The motion equation of the model subjected to horizontal seismic excitation was established, and the maximum relative sliding displacement was derived on a twice filtered Gaussian white noise with mean zero. A formula was given to judge the collapse of base sliding. By comparison of the diameter of column in Song and Qing dynasty with the critical displacement, it is drawn that the maximum slippage can not surpass the radius of the plinth’s top face even when the input excitation reaches 1000gal. The result shows the base-sliding-induced collapse never occurs even when buildings are subjected to super earthquakes.

Abstract: Existing safety study of building fire is mainly based on the ISO834 temperature-time curve, which is a theoretical curve and not fully reflect the influencing factors of fire such as the distribution of fuel and ventilation of the building. Secondly, the reliability analysis of building fire lacks explicit limit state function, especially when the reliability calculation considers the internal force redistribution of the structure. Direct Monte Carlo simulation has no requirement of explicit limit state function, but it needs huge calculation efforts. To solve these two problems, the response surface method is proposed from the view point of numerical simulation and experiment design. Using the fire modeling software CFAST the actual result of temperature and thickness of smoke layer can be obtained. On this basis, the reliability index can be calculated with the response surface method，which can solve the problem of lacking explicit limit state function by regressing multi-variable function based on the inputs and outputs. Uniform design (UD) method can allocate more parameters without greatly increasing the calculation efforts. Using a case the calculation process is explained with. The results show that this method can quickly obtain the reliability index in the premise of less calculation.

Abstract: To research the effect of earthquakes of different magnitudes on continuous rigid frame bridge under cantilever construction method, combined with the newly promulgated seismic design rules of highway bridges in China, finite element model has been built by Midas software by using the response spectrum method and dynamic time history analysis method to analyze cantilever construction method of the various stages of seismic response analysis. The results indicate that the bending moments of root segments of cantilever beams and the bottom sections of piers change greatly. So it should be attached importance to in design.

Abstract: Using the plastic shear deformation of panel zones (PZs) to increase the ductility and seismic energy dissipation of structures is a common practice in most countries specifications. This makes PZs generally yielding before columns and beams, and the shear deformation of PZs is relatively large. In order to explore the elasto-plastic properties of PZs, tests of different types of beam-column connections under monotonic loads were conducted firstly. Focus of tests is to explore the influence factors on elasto-plastic properties of PZs. Then based on test results and existing research data, simplified calculation methods of PZs strength and stiffness in the elastic and elasto-plastic stage were derived, and bilinear relationship expression of PZs moment-rotation was also given. Finally, the simplified calculation method for considering the effects of PZs elasto-plastic shear deformation on story drift of steel frames was presented.

Abstract: In order to research the nonlinear dynamic respond analysis of a new braced steel frame with wedge devices under the action of earthquake, its damping mechanism is analyzed, and the computational model is obtained. Based on the mechanism of multiple resistant lateral system, the explicit nonlinear dynamic analysis and dynamic contact algorithm are adopted to separately analyze the steel frame with no brace, with centric and eccentric brace, and with the new braced wedge block. During the analysis, in order to take the material and geometrical bi-nonlinear into account, the material model is chosen as the bilinear equivalent strength, and the explicit centered difference algorithm is adopted. It can be obtained from structural deformation and energy and so on. The results show that the stiffness of structure decays after plastic deformation in the earthquake effect, and the hysteresis energy consumption and system dumping appear. The nonlinear dynamic response of steel frame is affected by resistant lateral stiffness, plastic deformation, and system damping. The braced steel frame with wedge block regulates the displacement and acceleration response with yield energy dissipation of brace, as it provides resistance lateral stiffness to control the deformation. This kind of structure has strong adaptability to earthquake intensity and good seismic performance.