Study On The Aseismic Force Adjustment Coefficient Of Reinforced Concrete Frame Structures

With the continuous development of China’s construction industry, the designersput forward higher requirements of the multi-story frame building structure. Framestructure is a common structure form of reinforced concrete building, with goodbenefits of clear power transmission, structural layout flexibility, shock resistance andintegrity, has been widely used in various industrial and civil buildings.Most modern frame structure take "strong column-weak beam" frame structureyielding mechanism to ensure a good seismic performance. However, after theearthquake in Wenchuan, scholars have found that most of frame structure failed toachieve "strong column weak beam" requirement in the earthquake zone. To solve thisproblem, this paper combines several representative abroad specification anddocumentation of the relevant provisions to analyze the column moment amplificationcoefficient of the "Design of Concrete Structures"(GB50010-2010), and to determinethe value of adjustment coefficient with several numerical examples.In order to achieve "strong column-weak beam" and postpone frame columnsoccurrence of plastic hinges, Chinese norms improve the column end moments whichare obtained by elastic analysis and portfolio, namely, make the column end momentmultiply a "column-beam moment differential coefficient" which is greater than onebeam end moment. Since the operating is difficult, designers make column calculatedmoment multiply the "column-beam moment differential coefficient" directly to getthe column design moment.In this paper, as the new specification substantial increase the "column-beammoment differential coefficient"(from1.2to1.5in second seismic), which leads to asubstantial increase in column moment without increasingthe column axial force,causing not comply with the laws of mechanics phenomenon, we propose aamendment practice that uses frame column axial force and bending momentsimultaneous amplification method, which is required by "concrete high-rise buildingstructures of order"(JGJ3-2010) on the frame structure. By exploring theimplementation process of axial force and bending moment simultaneousamplification method, find that the "column-beam moment differential coefficient"can multiply the seismic effect directly, rather than multiply static load effectcombination which is prescribed by the specification, to reduce the waste. In this paper, by analyzing and numerical examples, taking the modified approach, whichadopts the axial force and bending moment simultaneous amplification method canachieve the "strong column-weak beam" effect which equally to only amplify momentin existing norms, and make a preliminary study on the value of moment differentialcoefficient.