Study On The Stair Structures’ Preformances Of Urban Village Residence

Urban village, what is usually saying that the village inside city. As China’s urbanization advancement, the countryside’s transformation is not complete in the city center or the edge of the city in the process of transforming, due to all kinds of subjective and objective reasons. As a result, it forms a living area with the original land and living function mainly in the use of land, and it is the stage production in the process of China’s urbanization.Because of the urban village residences are self-finance and self-built by the villagers, there is no normal design, non--governmental department supervision and management, no normal construction company, no strict quality inspection management when they were built, therefore most of urban village houses have a lot of problems since the beginning of the construction. What is worst, most of the villagers don’t have enough awareness of stair-system security, just think that stair is the belonging structure of a building because of the influence of traditional concepts, therefore, the stair-system structure safety performance of urban villages is worried.Strengthen the urban village multilayer residential stair-system structure safety as the starting point, our group masters the rich and first-hand information under the support of the "Zhengzhou Leading Talents"(201010LJRC186)project, chooses the representative urban villages of Zhengzhou city as research object. I have summarized and classified the common quality problems and earthquake damage by analyzing different structure types and different stair forms, and a shallow analysis have been made about the reasons that cause contribute to them. On the base of that I have made theoretical analysis and numerical simulation inoder to discuss the stair structure performance of different structure forms. Finally, according to the characters of frame-structure, reinforcement measures are put forward, and analyze its validity and rationality. Specific work as follows:1Our group has gone to urban villages of Zhengzhou to do the investigation, through taking photos, making survey, household interview by myself, and has obtained the common stair form, stair-system common quality problems and first-hand information of urban village residential in Zhengzhou.2On the basis of the research, I have sorted the common quality failing of urban village residential stair system (prefabricated stair system and cast-in-place reinforced concrete stairs) in the function, structure, performance and other aspects. From construction materials, structural systems, structural measure, used environment etc, comprehensive analysis structure and non structure factor that generates diseases. Through access to relevant data, I collected the stair system damage images of the Wenchuan earthquake, and sorted the seismic damage in detail and comprehensive.3Summarizing the traditional design method of residential stair system,and pointing out the shortages of traditional design method; according to the traditional method to design stairs, it only designs the separate staircase components and considers the dead weight load and live load, and the stairs without considering transverse loads, the relationship between stairwells and the main structure, not considering the effect of the stairs stiffness on the stiffness of the frame main body structure.4Simplifying the analysis about the lateral stiffnessfor of urban village stairs and the main structure, which gets the relationship of the lateral stiffness between the stair of unit and the main structure under lateral loads. The lateral stiffness of staircase designed by traditional method is greater than the lateral stiffness of the main structure. During the earthquake, more earthquake force are distributed to the stair, which is one of the reasons leading to the stairs damage ahead of the main structure in the earthquakes. At the same time points out the shortages of the simplified analysis method, for the convenience of this analysis method, the ladder platform, ladder board, middle rest column, frame column is approximately equivalent to bar, so it can’t reflect the actual working condition of the stair system under fixed lateral force.Contrasting the analysis results of the frame construction model whether consider the stair under the static load, I get the staircase’s effect on the performance of the framework of the overall structure, at the same time points out the shortages of this kind of analysis method.5To do dynamic characteristics analyses of urban village residential stair’s whole finite element model, and get the effect of the stairs on the main structure performance:the existence of the stairs, taking part in the overall structure work, increasing the stiffness of the structure, increaseing the natural frequency of vibration of the structure, and reducing the natural vibration period of structure.6To do the seismic response analysis of the local finite element model, whole finite element model of urban village residential stair. And get the internal force and change rule of the stair components under earthquake load and obtaine floor displacement and displacement between floors of the finite element models under the action of the earthquake, illustrating the staircase’s effect on the structure performance of body structure through the perspective of numerical...