Advanced Materials Research Vols. 255-260

Abstract: Ductility of concrete-filled steel box columns with binding bars and those without binding bars were discussed based on the experimental study. Two current methods were used to assess the ductility of concrete-filled steel box columns with binding bars and those without binding bars. Results show that binding bars can increase ductility of concrete-filled steel box columns. Ductility of concrete-filled steel box columns with binding bars at closer spacing is considerably better than that of concrete-filled steel box columns without binding bars.

Abstract: The determination of reasonable pile spacing is one of the key technologies in anti-slide pole board wall design. The previous study on soil arch effect merely consider the action of long duration load instead of short-term load (seismic force). Based on the soil arch effect, this paper take account of side slope grade and the influence of seismic force, and analyze the strained condition of soil arch between piles. Through the controlling conditions by soil arch effect, the paper obtain a reasonable formula for calculating pile spacing.Combining with high intensity earthquake, this paper analyze the relation between pile spacing and landslide thrust behind piles,soil cohesion stress and internal frictional angle. Finally, it takes the anti-slide pole board wall project in Chongqing-Lichuan railway for example to analyze and validate , then come to the point that there is a difference between general design and seismic design of anti-slide pole board wall.

Abstract: To solve design and construction problems of Monglian tunnel under high geothermal, based on the change rules of thermal parameters of surrounding rock and lining during excavation period, this paper analyzed the temperature distribution, heat transfer in tunnel and interaction between lining and surrounding rock, then by using numerical simulation, the relationship between temperature field and mechanical characteristics of lining and surrounding rock was discussed. Finally, the methods of using blast furnace cement, utilizing wet spraying concrete construction technology, and making surrounding rock exposure time as short as possible to reduce damages high temperature caused was proposed. The result can provide experience in similar tunnel design and construction.

Abstract: An orthogonal expansion method for earthquake ground motion was introduced in the first part of the paper. In the method, seismic acceleration process is represented as a linear combination of deterministic functions modulated by 10 uncorrelated random variables. In the second part of the paper, the recently developed probability density evolution method (PDEM) is employed to study linear random response of structures subjected to the external excitations. In the PDEM, a completely uncoupled one-dimensional governing partial differential equation, the generalized density evolution equation, is derived first with regard to evolutionary probability density function of the stochastic response for nonlinear structures. The solution of this equation can put out the instantaneous probability density function. So it is natural to combine the PDEM and the orthogonal expansion of seismic ground motion to study the linear random earthquake response. Finally, combining an example of a linear frame structure subjected to non-stationary ground motions, this paper validate the proposed approach and expounds the application of this method.

Abstract: A structural system reliability evaluation approach based on the idea of equivalent extreme-value event and the probability density evolution method is presented. Using the idea of equivalent extreme-value event, for a compound random event as combination of a set of random events, an equivalent extreme-value event could be constructed. So, this makes it possible to transform computation of the probability of the compound random event to a one-dimensional integration of the probability density function of the equivalent extreme-value random variable. In conjunction with the probability density evolution method, which is capable of evaluating the extreme-value distribution of a set of random variables or stochastic processes, the structural system reliability could be evaluated through computing the probability of the equivalent extreme-value event. The proposed approach is discussed in detail on how to construct the equivalent extreme-value event and then implement the procedure numerically. On the other hand, based on the orthogonal expansion method, the stochastic process of earthquake ground motion can be represented as a linear combination of deterministic functions modulated by a set of mutually independent random variables. Combining the above methods, the reliability of structures under earthquake excitations could be successfully evaluated. An example, of which deals with a linear frame structure subjected to non-stationary seismic loading, is illustrated to validate the proposed method.

Abstract: As important junction in lifeline transportation system, bridges are the most seismic vulnerable components. Based on the capacity/demand (C/D) analysis of bridge components, a practical method is established for seismic fragility assessment of long-span cable-stayed bridges. Depending on this approach, the seismic vulnerability assessment of the Wangdong Bridge, a cable-stayed bridge with a main span of 638m in Anhui Province, is conducted, and the feasibility of the approach is verified.

Abstract: In order to understand the rationality of the structural design for one hydropower underground house, based on reasonable selection of loading method for generator pier, and appropriate dealing with volute casing and draft tube water pressure. Take a typical underground house of anlagensektion to build the three-dimensional finite element model, and spectrum method was applied to analyze underground powerhouse anti-seismic characteristic. The seismic response characteristic of powerhouse just under seismic action and static load of normal operation jointly are investigated. The anti-seismic safety property of powerhouse is evaluated. It provides scientific basis for powerhouse dynamic design and operation control that station project.

Abstract: This paper presents a study on seismic resistance of typical single and double storey masonry buildings constructed in the southern districts of Pakhthunkhwa, Pakistan. Two types of bricks; wooden and rice husk burnt bricks, have been investigated in combination with mud and cement-sand mortar. Plane and reinforced specimens have been tested in axial compression and diagonal compression. Analysis of the experimental results show that both single and double storey buildings constructed in the study area with mud mortar and mud plaster are seismically vulnerable. However application of the wire mesh on wall surface subsequently plastered increases the strength significantly and make the structure resistant to the earthquake forces.

Abstract: This paper presents an experimental study on the improvement of unreinforced block masonry buildings against earthquake disasters. Unreinforced concrete block masonry piers have been tested for lateral strength before and after retrofitting. Welded mesh and injection of cement grout techniques have been used for piers retrofitting. The analysis of experimental results demonstrates that proper retrofitting can decrease the risk to concrete block masonry buildings in future scenario earthquakes. Retrofitting increases not only the overall strength of unreinforced masonry piers but also the ductility.

Abstract: Based on the appraisal reports of primary and secondary school in Kunming and the statistical analysis of RC frame structure buildings, evaluation of earthquake resistance capacity was given. Problems affecting functions of the RC frame structure were analyzed to facilitate the reconstruction and fetrofit of this sort of RC frame structure.