外挑式場館建筑的動力性能
扶長生，周立浪
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(上海長福工程結(jié)構(gòu)設(shè)計事務(wù)所，上海 200011)［摘要］通過世博會兩個工程實例，建立外挑式場館建筑非耦聯(lián)系統(tǒng)的分布參數(shù)力學(xué)模型。它們的體型空曠而矮胖，質(zhì)量大都分布在主體框架或剪力墻的外側(cè)，具有相當(dāng)大的轉(zhuǎn)動慣量。無阻尼自由振動的分析結(jié)果表明，扭轉(zhuǎn)往往為第一振型。進一步分析和論述了平扭耦聯(lián)系統(tǒng)偏心率和頻率比Ω對地震反應(yīng)的影響。當(dāng)Ω=1時，系統(tǒng)對扭轉(zhuǎn)反應(yīng)相當(dāng)敏感。對于小偏心系統(tǒng)，當(dāng)Ω≤0.75或Ω≥1.25時，扭轉(zhuǎn)效應(yīng)會顯著減小。對外挑式場館建筑，拘泥于限制扭轉(zhuǎn)不為第一振型不一定是完全合適的。它們的抗震性能應(yīng)該從振型、頻率比、位移比、層間位移角等幾個方面進行綜合評價。［關(guān)鍵詞］外挑式場館建筑；扭轉(zhuǎn)振型；偏心率；頻率比Dynamic behavior of stadium-type buildings with cantilever structuresFu Changsheng, Zhou Lilang(Shanghai ChinaFu Structural Design Inc., Shanghai 200011, China)Abstract:On basis of two EXPO engineering projects, the uncoupled model with distributed mass and stiffness is presented for stadium-type buildings with cantilever structures. The results of free vibration analysis show that torsion will be easy to be the first modal shape of the system, which has properties of the low ratio of building height to planar dimensions and the large gyration radius of mass. For the torsion-coupled system, both eccentricity and frequency ratio Ω are important design parameters. For the system with small eccentricity, whether Ω≤0.75 or Ω≥1.25, the seismic torsion responses will be greatly reduced. As the eccentricity being larger, the modal shape will be coupling each other, especially when Ω=1. It is reasonable for the tall buildings to stipulate that the torsional modal shape must not be the first one to reduce the torsion responses, because the first modal shape will be translational, when it is well designed. However, it may not be necessary to control the order of the modal shapes for the stadium-type buildings with outrigger structures. Their dynamic behavior should be estimated by using the design parameters, such as eccentricity, frequency ratio, lateral stiffness, torsion displacement ratio, and so on.Keywords:stadium-type buildings; cantilever structures; torsional modal shape; eccentricity; frequency ratio作者簡介：扶長生(1944-)，男，上海人，教授級高工，董事長，Email:cfstruct@vip.sina.com。參考文獻［1］JGJ3—2002高層建筑混凝土結(jié)構(gòu)技術(shù)規(guī)程［S］.北京：中國建筑工業(yè)出版社，2002.［2］CHOPRA A.K. Dynamics of structures: theory and application of earthquake engineering［M］. N.J.：Prentice-Hall, Englewood Cliffs, 1971.［3］扶長生.抗震設(shè)計中的平扭耦聯(lián)問題［J］.建筑結(jié)構(gòu)學(xué)報，2006,27(2):40-46.［4］TSO W K, DEMPSEY K M. Seismic torsional provisions for dynamic eccentricity［J］. J. of Earthquake Engineering and Structural Dynamics, 1980, 8(3): 275-289.［5］TSO W K. Torsions in multistory buildings［C］//Proc.of the Third International Conference on Tall Buildings, Hongkong & Guangzhou, 1984: 1-7.［6］徐培福，黃吉鋒，韋承基. 高層建筑結(jié)構(gòu)在地震作用下的扭轉(zhuǎn)振動效應(yīng)［J］. 建筑科學(xué), 2000, 16(1): 1-6.［7］NEWMARK N M, ROSENBLUETH E. Fundamentals of earthquake engineering［M］. N.J.：Prentice-Hall, Englewood Cliffs, 1971.［8］陳以一，張大照，薛偉辰，等. 承載開閉鋼屋蓋的預(yù)應(yīng)力混凝土看臺結(jié)構(gòu)抗震性能研究［J］. 土木工程學(xué)報, 2007, 40(8): 22-28.［9］建設(shè)省住宅局建筑指標(biāo)課，日本建筑主事會議. 建筑物の構(gòu)造規(guī)定-建筑基準法施行第3章の解說と運用［M］. 日本建筑セソタ，平成6年.［10］魏璉，王森. 論水平地震作用下對稱和規(guī)則結(jié)構(gòu)的抗扭設(shè)計［J］. 建筑結(jié)構(gòu), 2005, 35(5): 13-17.
