【導讀】受彎鋼結點的周期性行為。梁的試樣由變截面梁，翼緣以及縱向的加勁肋組成。測試樣加載軸向荷載和側向位移用以模擬側向荷載對組合梁抗彎系統(tǒng)的影響。結果表明試樣在旋轉角度超過弧度后經歷了從塑性到延性的變化。肋的存在幫助傳遞軸向荷載以及延緩腹板的局部彎曲。尺寸的樣品進行了測試。這些測試打算評價為舊金山展覽中心擴建設計的受彎結點。在滿足設計基本地震等級和最大可能地震等級下的性能。在地震類荷載的作用下，CGMRFS梁的最終彎矩將考慮到可變軸向力的影響。中的軸向力是切向力連續(xù)積累的結果。非線性靜力推出器模型是以典型的單間CGMRF模板為指導。顯示了塑性鉸的荷載-應變行為是通過建筑物地震恢復的。NEHRP指標以廣義曲線的形式逼近的。內力分布圖解見，可見，彈性范圍和非彈性范圍的內力行為基本相同。在四個RBS同時屈服后，發(fā)生在腹板與翼緣端部的豎向的統(tǒng)一屈服將開始形。經測定的梁翼緣屈服應力值等于。切除30%翼緣寬度。以便消除襯墊板條帶來的斷口效應并增加

　　

【正文】 e bottom flange and portion of the web next to the bottom flange as shown in Fig. 14. The length of this buckle extended over the entire length of the RBS. Plastic hinges developed in the RBS with extensive yielding occurring in the beam flanges as well as the web. Fig. 15 shows the crack that initiated along the transition of the RBS to the side wing plate. Ultimate fracture of specimen 1 was caused by a fracture in the bottom flange. This fracture resulted in almost total loss of the beam carrying capacity. Specimen 1 developed rad of plastic rotation and showed no sign of distress at the face of the column as shown in Fig. 15. . Specimens 3 and 4 The response of specimens 3 and 4 is shown in Fig. 16. Initial yielding occured during cycles 7 and 8 at 1_y with significant yielding observed in the bottom flange. Progressing through the loading history, yielding started to propagate along the bottom flange on the RBS. During cycle initiation of web buckling was noted adjacent to the yielded bottom flange. Yielding started to propagate along the top flange of the RBS and some minor yielding along the middle stiffener. During the cycle of a severe web buckle developed along with flange local buckling. The flange and the web local buckling bec ame more pronounced with each successive loading cycle. During the cycle y, the axial load was increased to 3115 KN (700 kips) causing yielding to propagate to middle transverse stiffener. Progressing through the loading history, the flange and the web local buckling became more severe. For both specimens, testing was stopped at this point due to limitations in the test setup. No failures occurred in specimens 3 and 4. However, upon removing specimen 3 to outside the laboratory a hairline crack was observed at the CJP weld of the bottom flange to the column. The maximum forces applied to specimens 3 and 4 were 890 kN (200 kip) and 912 kN (205 kip). The loadcarrying capacity deteriorated by 20% at the end of the tests for negative cycles due to the web and the flange local buckling. This gradual reduction started after about to rad of plastic rotation. The loadcarrying capacity during positive cycles (axial tension applied in the girder) did not deteriorate as evidenced with the slope of the force–displacement envelope for specimen 3 shown in Fig. 17. A photograph of specimen 3 before testing is shown in Fig. 18. Fig. 19 is a Fig. 16. Hysteretic behavior of specimens 3 and 4 in terms of moment at middle RBS versus beam plastic rotation. photograph of specimen 4 taken after the application of rad displacem ent cycles, showing yielding and local buckling at the hinge region. The beam web yielded over its full depth. The most intense yielding was observed in the web bottom portion, between the bottom flange and the middle stiffener. The web top portion also showed yielding, although less severe than within the bottom portion. Yielding was observed in the longitudinal stiffener. No yiel ding was observed in the web of the column in the joint panel zone. The un reduced portion of the beam flanges near the face of the column did not show yielding either. The maximum displacement applied was 174 mm, and the maximum moment at the middle of the RBS was times the plastic mom ent capacity of the beam. The plastic hinge rotation reached was about rad (the hinge is located at a distance from the column surface,where d is the depth of the beam). . Strain distribution around connection The strain distribution across the flanges–outer surface of specimen 3 is shown in Figs. 20 and 21. The readings and the distributions of the strains in specimens 1, 2 and 4 (not presented) showed a similar trend. Also the seque nce of yielding in these specimens is similar to specimen 3. The strain at 51 mm from the column in the top flange–outer surface remained below % during negative cycles. The top flange, at the same location, yielded in pression only. The longitudinal strains along the centerline of the bottom–flange outer face are shown in Figs. 22 and 23 for positive and negative cycles, respectively. From , it is found that the strain on the RBS bees several times larg er than that near the column after cycles at –。 this is responsible for the flange local buckling. Bottom flange local buckling occurred when the average strain in the plate reached the strainhardening value (esh _ ) and the reducedbeam portion of the plate was fully yielded under longitudinal stresses and permitted the development of a full buckled wave. . Cumulative energy dissipated The cumulative energy dissipated by the specimens is shown in Fig. 24. The cumulative energy dissipated was calculated as the sum of the areas enclosed the lateral load–lateral displacement hysteresis loops. Energy dissipation sta rted to increase after cycle 12 at y (Fig. 19). At large drift levels, energy dissipation augments significantly with small changes in drift. Specimen 2 dissipated more energy than specimen 1, which fractured at RBS transition. However, for both specimens the trend is similar up to cycles at q = rad In general, the dissipated energy during negative cycles was times bigger than that for positive cycles in specimens 1 and 2. For specimens 3 and 4 the dissipated energy during negative cycles was 120%, on the average, that of the positive cycles. The bined phenomena of yielding, strain hardening, inplane and out ofplane deformations, and local distortion all occurred soon after the bottom flange RBS yielded. 6. Conclusions Based on the observations made during the tests, and on the analysis of the instrumentation, the following conclusions were developed: 1. The plastic rotation exceeded the 3% radians in all test specimens. 2. Plastification of RBS developed in a stable man