Research On Structural Design Technology Of Large Substation In High Seismic Intensity Area Based On Chinese And American Codes

American codes are widely adopted and accepted internationally,as more and more Chinese enterprises participating in international engineering projects,there is an urgent need for Chinese engineers to have a deep understanding and grasp of American codes,and correctly apply them to practical engineering design.The background of this thesis is a large-scale substation project in high seismic intensity area,the differences in the design of reinforced concrete moment frame structures with Chinese and American codes in high seismic intensity area are compared and analyzed,the key content and scientific application of American codes in practical application are studied,so as to provide reference for Chinese engineering designers to understand American codes.The main research contents and conclusions are as follows:1)Based on the common design codes of concrete structures in China and the United States,the basic contents of the codes are compared and studied,including the strength evaluation criterion and the value of elastic modulus for concrete and rebar,reliability index and reliability design method,dead and live load,wind load,seismic load and load combination,etc.In engineering design,the characteristic value of concrete strength and the value of strength used in design should be distinguished,and the reliability system should be consistent with other relevant contents of design codes,so as to achieve the expected safety level of code;the value of live load on floors in American codes is usually slightly larger than that in Chinese codes,in addition to the live load on floors stipulated in the code,the engineering design should also consider the load of equipment layout,maintenance and operation;the calculation of wind load in American codes is more complicated,and the simplified method can be used to calculate the wind load according to the actual situation;there are great differences between American and Chinese codes in seismic design,to fully recognize and understand these differences is the key to correctly and reasonably apply American codes in practical engineering.2)The modeling calculation and design analysis of engineering examples are carried out by using common structural design software under the conditions of Chinese and American codes,the results show that:in the case that the basic wind speed of American codes is equivalent to that of Chinese codes,the calculation results are different due to the great difference of wind load calculation methods;the response modification coefficient（R）and the overstrength factor（Ω₀）in structures with different ductility have a direct effect on the result of the earthquake action calculation,structures with different ductility have different requirements for seismic measures,which are similar to Anti-Seismic Grade in Chinese codes;the influence of section cracking on stiffness should be considered in the calculation of bearing capacity and story drift of reinforced concrete structure in American Codes;in high seismic intensity area,considering the combination of seismic action,the reinforcement ratio of frame beam calculated by Chinese codes is lower than that calculated by American codes,and the reinforcement ratio of frame column is higher than that calculated by American codes.3)The seismic measures of high ductility reinforced concrete moment frame in Chinese and American codes are analyzed and studied from the aspects of section size,internal force adjustment and reinforcement measures.According to the research:reasonable section size can effectively ensure the restraint of the frame beam on the frame column,so that the joint can effectively transfer the load;the internal force adjustment of the reinforced concrete moment frame includes"strong-column/weak-beam"and"strong-shear/weak-bending",for the high ductility structure,the bearing capacity is adjusted according to the actual reinforcement calculation,and for the structure with low ductility,the bearing capacity is adjusted under the design load;Chinese and American codes have different emphases of seismic measures,but their overall requirements are relatively similar,in engineering design,the requirements of Chinese and American codes can be considered comprehensively,and the most reasonable seismic measures can be selected according to the actual needs.