Simulation And Analysis Of Anti-seismic Performances On Typical Rural Structure In The Middle Reaches Of Yangtze River

Lacking of anti-seismic design,some residential buildings in poor rural areas are prone to be damaged or collapse when the earthquakes occurred.The middle reaches of Yangtze river is characterized by prominent location,complicated topography,masonry structures and high frequency of medium-small earthquakes.In order to enhance and improve the seismic behavior of the rural residential buildings effectively,in the paper,the typical masonry structure in the middle reaches of Yangtze river is selected as the object,and the effects of the different factors on the seismic behavior and collapse resistance of masonry structure,such as different types of wall,floor type,the presence of ring beam and constructional column are studied by using the reasonable numerical simulation method.The main research contents and results are as follows:1.By summarizing the present research results,the existed questions of finite element method and discrete method in simulating the collapse process on masonry structure are pointed out.A coupling method of DDA and FEM is proposed to solve the problems.It is briefly demonstrated that the new method in simulating the collapse process on masonry structure is applicable.2.The general methods of modeling reinforced concrete members and masonry walls in masonry structure are classified and summarized.By combining with the characteristics of typical masonry structure in the middle reaches of Yangtze River,a more suitable model is established,in which the Cullen Moore's law and Newton's second law is ued to simulate the forces between units instead of the useless unit.The rule of preventing penestration of DDA method is used to control of the separation and intrusion process of the blocks.3.Referring to the relevant code and calculation formula,the reasonable material parameters is ditermined in the simulation.Through large amount of trial and algorithm analysis,the contact between different components is treated respectively.The appropriate single-sided contact and tide-break contact are used.The initial stress caused by initial gravity among elastic blocks is eliminated by dynamic relaxation.4.By analyzing and comparing the results of different models under earthquake with different acceleration peak values,it is concluded that,(a)the solid walls and site casting without seismic construction measures of masonry structure can roughly resist the earthquakes with intensity of 7.(b)Under the influences of large earthquake,some weak places,such as the places near the windows and doors in the lower level,will firstly produce inclined cracks.(c)Then the underlying structure will suffer from destruction,eventually it will lead to the damage and collapse of the layer structures.(d)Both the cavity wall with the sleep and sleepness cannot resist the earthquakes with epicentral intensity of 7.(e)Compared with precast slab,cast-inplace floor slab is more conducive to the overall integrity of the structure,to a certain extent,it also can improve the behavior of masonry structure under earthquake.(f)Compared with the masonry structures without seismic construction measures,those with seismic construction measures,the using of ring beam and constructional column can greatly improve the ability of deformation resistance and delay the structure collapse time.According to the analysis,for rural masonry structure in the middle reaches of Yangtze river,solid walls and cast-in-place floor slab are highly recommended.And the correct set of the ring beam and constructional column is necessary as well.The ability of anti-earthquake and collapse resistance of masonry structure will be effectively improved.