Research On The Structural Design And Construction Technology Of Prefabricated Central Cone Sil

The central cone silo is now an ideal form of pre-equalization of bulk materials such as cement storage and raw material homogenization storage as its special structure and good process performance.However,the structural design of the central decompression cone lacks unified standards and clear guidance.In practical engineering,the decompression cone mostly adopts the traditional cast-in-situ structure,which leads to a complex construction process,a long construction period,and its construction quality is also difficult to guarantee,then resulting in frequent silo diseases.With the advantages of shorter construction period,temslab saving,energy saving and environmental protection,prefabricated structure has increasingly become a structural form of national promotion.At present,there is still a lack of relevant research and achievements on the structural design and prefabricated assembly technology of central cone silo at home and abroad.Therefore,this paper takes the central cone silo provided by a design institute as the prototype,then completes the structural design and prefabricated assembly technology research of the central cone silo by ABAQUS finite element software combined with Python script,including the main research contents below:(1)The differences of storage load of four silo standards(ACI 313-16),Australia(AS3774-1996),Europe(EN 1991-4:2006)and China(GB 50077-2017)under central and eccentric loading and unloading were compared.Taking cement storage as an example,the differences of internal force distribution between silo wall and central cone under different loading and unloading conditions were compared.The results show that the circumferential axial forces of silo wall are all tension when central loading and unloading,which is basically controlled by European standard(EN 1991-4:2006),and the vertical axial forces of silo wall are all pressure,which is basically controlled by the Chinese standard.The circumferential and vertical axial forces of the cone are both pressure which are all controlled by the Chinese standard(GB 50077-2017).In eccentric loading and unloading,the circumferential axial force control condition of silo wall under European standard is when r_c=0.6r.The circumferential bending moment and vertical section shear control condition of silo wall are when r_c=0.4r,and the cone internal force control condition is when r_c=0.6r.(2)Taking the common central cone silo in engineering as an example,the structural design work is completed,and the reinforcement differences under Chinese and European standards are compared.The parameters of height-diameter ratio and cone top angle of the silo are analyzed.The results show that:The circumferential and vertical reinforcement control conditions of the silo wall under European standards are large eccentric unloading which is r_c=0.4r.In the range of 10 m from the bottom of the silo wall,the circumferential reinforcement of the silo wall is slightly larger under the Chinese standard,and its large part is controlled by the European standard.The hoop and vertical control reinforcement of the cone are very close under the two standards.The circumferential reinforcement of silo wall increases with the increase of height-diameter ratio,while the cone reinforcement is not sensitive to the change of height-diameter ratio.With the increase of the cone top angle,the circumferential and vertical reinforcements of the cone decrease slightly,but the maximum variation is only 3.2%.(3)Based on the reinforcement results of the integral central cone silo,the design of the cone prefabrication assembly scheme is completed,and the parameter analysis is carried out on the number of split parts of the precast slab,the top angle of the central cone and the inner diameter of the silo.The results show that:The hoisting condition of the precast slab plays a controlling role in the vertical reinforcement of the central cone.With the increase in the number of split parts of the precast slab,the vertical control reinforcement on both sides of the bottom and middle of the precast slab decreases slightly,and the vertical control reinforcement on the top and middle of the precast slab increases significantly.With the increase of the central cone angle,the vertical control reinforcement of each part of the precast slab increases.With the increase of the inner diameter of the silo,the vertical control reinforcement at the top of the precast slab changes little,and the vertical control reinforcement at each part of the precast slab increases.(4)The checking calculation of precast slab hoisting construction stage was completed,and the finite element analysis of the bending performance of the key joints of the prefabricated central cone was carried out.The simplified calculation method of the load of each control section of the joint beam was proposed.and the elastic-plastic analysis of the whole silo with the prefabricated central cone was finished.The results show that:In the precast slab hoisting stage,except that the maximum principal stress of a few elements near the hoisting point and the variable section is close to or slightly exceeds the standard value of the tensile strength of C40 concrete,most regions are in the elastic stage,and the stress of the steel bar is also lower than the yield strength.With the increase of the internal angle and the thickness of the bottom slab,the bending performance of the joint beam gradually decreases.When the thickness of the bottom slab increases to 300 mm and above,the control section transfers from the variable cross section of the precast slab to the middle span.According to the simplified formula,the critical thickness of the bottom slab when the control section transfers is about 330 mm.Under the conditions of central loading and large eccentric unloading,the circumferential and vertical maximum stress of concrete in silo wall and cylinder wall are less than the standard value of C40 concrete strength,and the stress of steel bar is less than the yield strength.Except at the connection between the bottom of precast slab and the bottom of cone ring beam,the maximum principal stress of small part of concrete exceeds the standard value of C40 concrete tensile strength,and the stress of small part of steel bar reaches the yield strength,all the other regions meet the design requirements.