Report - PEER - University of California, Berkeley

the relationship between the moment and plastic rotation taken to be bilinear. InJapan, such analyses are commonly adopted in seismic design practices. Since theanalyses were carried out prior to the test, nominal strength values were adopted forthe material strengths. The four cases shown in Table 1 were analyzed. In somecases of analyses, composite action with RC floor slabs was taken into account, andboth the stiffness and strength of composite beams were adjusted using the concept of“effective width.” Using the effective width stipulated in the Japan’s composite slabguideline, the elastic stiffness of the beams was enlarged by 1.8 times, and thepositive moment strength was enlarged by 1.5 times, respectively. In some cases ofanalyses, panel-zone behavior, i.e., the size, flexibility, and yielding of panel-zoneswere also considered. The panel-zone strength was enlarged by 1.3 times the valuescalculated using the design equations. This is also a common practice in Japan toallow for rather significant hardening sustained by panel-zones. In all cases, no strainhardening after reaching the respective strength was considered. This is again acommon seismic design practice in Japan. According to comparison between the testand analysis [Fig. 8(a)], the elastic stiffness and yield strength are very close to eachother; in particular the difference (for both the elastic stiffness and yield strength) isnot greater than 1% for Case 4. This observation indicates that numerical analysescommonly used in seismic design is very reasonable in terms of the prediction of thetwo most important structural properties, i.e., the elastic stiffness an yield strength.Table 1. Analysis cases in pushover analysisAnalysis case Composite action Panel-zone effectCase 1 Not considered Not consideredCase 2 Considered Not consideredCase 3 Not considered ConsideredCase 4 Considered ConsideredForce (kN)1000Force (kN)1000-0.04 0.04Drift angle(rad)-0.04 0.04Drift angle(rad)(a)-1000Case1Case2Case3Case4(b)-1000Figure 8. Comparison between test and numerical analysis: (a) before test;(b) after test.277