| Reinforced concrete components are mostly in complex stress state undercombined loading, and there is correlation among the stress.The capacity of RC component under combined load is calculated separately inGB50010-2002, which the stress state of component can’t reflection truly and willlead to an unreasonable design.In order to research the rule about correction of force, some work was carried outas follow:Based on the thought of correlation, experiment date of component under theloading of bending and shear were collected and contradicted with the design methodof code, the code design method can’t reflect the true force state and will introducethe component danger to resist the action of loading. Considering the correlationabout bending and shear,1/4arc model and parabola model were proposed. Besides,the calculation method about1/4arc model is proposed. The correlation of shear andbending is considered in this formula. Results show that the computing model of themodified formula is more accurate and its reliability can meet approximately thedemand of GB50068-2001.In GB50010-2002, the Mu-Nu relevant curve composed of two relevant curves couldn’ttransit well, and the small eccentric curves couldn’t be connected with the axial point, whichcause the calculation results with small eccentric formula near axial compression point to beunsafe. Two unified calculation method are derived to connect pure bending, eccentriccompression and axial compression. The formulas have a definite physical meaning. Throughthe convergence between the small eccentric compression curves and axial compression point,these issues can be solved effectively. By compared the curve of unified formula with that ofcode, which is consistent relatively, the judge of the type of eccentricity can be cancelled andthe calculated reinforcement area can be returned to the unified formula for checking. Theresults show that there is a reinforcement mutation between small eccentricity formula andaxial compression formula of the code. The small eccentric formula near axial compressionpoint is not safe. The reinforcement calculation of the unified formula has a good transitionand can meet the demand of GB50068-2001.Proceeding from the Mu-Nu relevant curve, the force of beam of frame structurewas analysis under the act of earthquake. Beam under rare earthquake may besubjected to axis force and became a member under eccentric compression. Compared to beam-columns,the beam would design safer. Based on this, ensuring the reliabilityindex of beam and increasing the seismic reliability of column to achieve “strongcolumn and weak beam†mechanism, beam hinge mechanism is realized by increasingthe reinforcement of beam.Based on the research about the correlation of bending and shear and thecorrelation of axial and bending, by increasing the part of shear into compression(tension)-bending interaction equation, the paper presents a formula considering theoverall interactions of compression (tension), shear and bending. The formulareasonably reflects the real force state of members and is agreed well with theexperiment data. Finally, strength envelope of the compression (tension)-bendinginteraction equation was drawn according the formula. The strength envelope can beused to obtain the stress state of member easily and evaluate the security of membersunder combined compression (tension), shear and bending. It can be used as acriterion to determine member dissociation in the collapse analysis... |
