33 2 2011 4 ol. 33 No. 2 Apr. 2011 1002-8412 2011 02-0104-08 1 1 1 2 361003 3. 361009 3 1. 361005 2. GB50023-2009 TU746. 3 A Study on Single-span RC Frame Reinforced with Steel Truss System Yuan Xing-ren 1 Zhang Peng-cheng 1 Lin Shu-zhi 1 2 Liao Wen-bin 3 1. School of Architecture & Civil Engineering Xiamen University Xiamen 361005 China 2. Xiamen Construction and Administration Bureau Xiamen 361003 China 3. Xiamen Zhongfuyuan Architecture Design and Research Institute Xiamen 361003 China Abstract Single-span frame are used in a general way in school buildings. After Wenchuan earthquake all school buildings are raised to B fortification. According to national seismic appraisal criteria GB50023-2009 frame structure is not appropriate for single-span frame B fortification should not be single-span frame structure. With lack of redundant constraints single-span frame structure is a weak seismic system and easily to collapse. Existing buildings need to be strengthened to improve seismic performance. Generally strengthening components is costly and complexly yet ineffectively comparing with other structural methods. Adding brace is a way to change frame system to brace-frame system. In this paper based on a practical engineering the building seismic performance after strengthened with steel braces and some concomitant problems which should arouse engineer s attention are discussed. The research shows that using braces to change structural system can improve seismic performance of buildings practically and cost-effectively. Keywords seismic design single-span frame steel brace seismic strengthening E-mail yxr2020007@ sina. com 1 5. 12 1 2 GB50023-2009 2010-01-20 April 2011
33 2 105 2 2. 1 1 1 Fig. 1 Frame calculation model 1 mm Table 1 Joints displacement mm 2 3 5 6 7-15. 67-11. 60-5. 23 3-2. 04-1. 45-0. 69 2. 2 1 4 6 15. 67mm 2. 04mm 87% K α 2 Fig. 2 Internal force of initial frames ol. 33 No. 2 2011
106 2011 4 3 Fig. 3 Interal force of braced frame 4 T T g 5T g 4 4 Fig. 4 Stiffness distribution of frames 3 u = 4K + 2 1 + α K = 6K + 2αK 3 4 = 1 1 + α + α K = 2K 3 + α 1 2 3 + α 2 1 2 5 6 = 2K 3 + α K = 2 3 + α η 1 = 1 + α 2 3 + α / 6-1 = 2α 3 + α η 2 = 1-2 3 + α / 6 = 4 5 η 1 η 2 α 3 + α 3 4 5 α = 1 η 1 = 0. 5 η 2 = 0. 25 2. 3 4 T 1s X 5 Fig. 5 Seismic coefficient curve α April 2011
33 2 107 2. 4 4 ~ 6 5 6 6 Fig. 6 6 The constitution of frame joint and column reinforcement 7 N φ 5mm 75mm GB50010 α a α a = 40mm 4mm 20r r 1. 0 α a = 0. 9 f a 500mm GB 50017 A a r 7mm 3 3. 1 Ⅱ T g = 0. 35s N 0. 9φ f c0 A c0 + f y0 A s0 + α a f a A a 6 3 ol. 33 No. 2 2011
108 2011 4 Fig 7 7 The arrangement plan of the structure 7 0. 10g 13. 6m 3. 6m C30 C25 HRB335 6 3. 2 7 0. 1g 0. 15g 8 Y Pushover Fig. 8 The plastic hinge location under 8 1 2 8 the Y direction earthquake 1 2 100mm 96mm 5. 3mm 9 a 7 8 9 1 2 Y 0. 15g 7 2 4 10 1 2 9 b 1 /808 1 /2948 1 /2030 3. 3 2 2 1 1 PKPM 2 April 2011
33 2 109 2 1 Table 2 The comparison of reinforcement of the first floor beams and columns 5-5 0. 8-0 17-0-9 4-7-6 0. 4-0. 4 5 1 5-5 0. 8-0 KJL-3 1 8-0-5 4-6-4 0. 4-0. 4 2 5-5 0. 8-0 2 10-0-7 4-6-4 0. 4-0. 4 5-5 0. 8-0 19-0-12 4-9-5 0. 6-0. 4 6 1 5-5 0. 8-0 KJL-4 1 11-0-8 4-9-4 0. 4-0. 4 2 5-5 0. 8-0 2 12-0-9 4-9-4 0. 4-0. 4 5-5 0. 8-0 19-0-12 4-9-5 0. 6-0. 4 7 1 5-5 1. 3-0 KJL-5 1 11-0-8 4-9-4 0. 4-0. 4 2 5-5 1. 5-0 2 12-0-9 4-9-4 0. 4-0. 4 5-5 0. 8-0 17-0-9 4-7-6 0. 4-0. 4 8 1 5-5 1. 0-0 KJL-6 1 8-0-5 4-6-4 0. 4-0. 4 2 5-5 1. 3-1. 0 2 10-0-6 4-6-4 0. 4-0. 4 5-5 0. 8-0 17-0-9 4-7-6 0. 4-0. 4 9 1 5-5 1. 3-0 KJL-7 1 8-0-5 4-6-4 0. 4-0. 4 2 5-5 1. 5-0 2 10-0-6 4-6-4 0. 4-0. 4 5-5 0. 8-0 21-0-12 4-10-6 0. 6-0. 4 10 1 5-5 1. 0-0 KJL-8 1 11-0-7 4-10-4 0. 5-0. 4 2 5-5 1. 3-1. 0 2 14-0-9 4-10-4 0. 5-0. 4 5-5 0. 8-0 7-0-7 4-3-4 0. 4-0. 4 13 1 5-5 1. 3-0 KJL-16 1 6-0-6 4-3-4 0. 4-0. 4 2 5-5 1. 3-0 2 6-0-6 4-3-4 0. 4-0. 4 5-5 0. 8-0 5-0-5 4-3-4 0. 4-0. 4 14 1 7-7 1. 0-1. 0 KJL-17 1 5-0-5 3-2-3 0. 4-0. 4 2 5-5 1. 0-1. 0 2 5-0-5 3-2-3 0. 4-0. 4 15 16 5-5 0. 8-0 1 5-5 1. 0-0 2 5-5 0. 8-0 5-5 0. 8-0 1 5-5 0. 8-0 2 5-5 0. 8-0 cm 2 Asx-Asy Asx-x Asy-y GA-B A B As1-As2-As3 As1 As2 As3 GA-B A B 11 985. 2kN 1 2 1418. 1kN 1406. 8kN 1 39. 7% 12 12. 9mm 1 2 ol. 33 No. 2 2011
110 2011 4 Fig. 9 9 The arrangement of steel braces 10 Y Fig. 10 The story drift in Y-direction 11 Y Fig. 11 The story shear force in Y-direction Fig. 12 12 Y The floor displacement in Y-direction 3. 80mm 5. 6mm 1 70. 54% 3. 4 1 2 2 3. 5 April 2011
33 2 111 13 Fig. 13 13 Flowchart of reinforcement References 1. J. 2008 30 3 84 ~ 87 Lin Shu-zhi. Some Suggestions for Building Strengthening & Building Design after the Wenchuan Earthquake J. Earthquake Resistant Engineering and Retrofitting 2008 30 4 84 ~ 87 in Chinese 2 GB50023-2009 S GB50023-2009 Standard for Building Seismic Appraisal S in Chinese 3. M. 2006 Song Tian-qi. Structural Design of Tall Buildings M. Chongqing Chongqing University Press 2006 in Chinese 4. M. 2003 Shang Shou-ping Zhou Fu-lin. Seismic Design of Building Structures M. Beijing Higher Education Press 2003 in Chinese 5. J. 2005 26 1 91 ~ 96 Fu Jian-ping Zhang Chuan Bai Shao-liang. Quantitative Evaluation of two Shear Transfer Mechanisms in Earthquake-resistant Beam-column Joints J. Journal of Building Structures. 2005 26 1 91 4 ~ 96 in Chinese 6. J. 1999 31 3 40 ~ 45 Bai Yu-fei Liu Chang. Shear Performance Analysis of the Wrapped Steel Joint J. Journal of Harbin University of C. E. & Architecture 1999 31 3 40-45 in Chinese 7 GB50367-2006 S GB50367-2006 Design Code for Strengthening Concrete Structure S in Chinese 1986 ~ ol. 33 No. 2 2011