考虑温度历程的补偿收缩混凝土墙应力计算
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摘要
补偿收缩混凝土是解决地下室侧墙混凝土收缩裂缝的有效途径,业已用于大型建筑、超长地下室侧墙混凝土的裂缝控制,但其设计方法还停留在“试验—估算”的经验水平上。这使得补偿收缩混凝土的设计不确定性增加,可靠性降低;工程中一些补偿收缩混凝土达不到预定效果,混凝土依然开裂。这无疑限制了补偿收缩混凝土的推广应用。可见,建立合理的设计计算方法,是补偿收缩混凝土应用的重要课题,具有重要的理论和工程意义。
本文从补偿收缩混凝土的原理出发,介绍了在小限制、中等限制和大限制三类限制条件下的补偿收缩模式,建立了大体积、大截面混凝土冷缩和干缩联合补偿收缩模式。在此基础上,计算了武汉市某地下室侧墙混凝土30d最终变形,计算出膨胀剂在墙体中建立的压应变。
本文以ANSYS为平台,全面系统地实现该工程施工期间补偿收缩混凝土温度场和温度应力的仿真分析计算,研究了钢筋内约束与底板外约束之间的关系、探讨了考虑温度历程的补偿收缩混凝土的膨胀模拟的实现;根据地下室侧墙混凝土温度应力分布及变化规律,对掺入膨胀剂后墙体温度应力仿真结果与经验设计法计算结果进行比较,预测了膨胀剂建立的预压应力及抗裂效应。经合理设计的补偿收缩混凝土,能有效防止侧墙混凝土施工期收缩引起的裂缝,并能有效地预防墙体后期可能出现的干缩裂缝。
本文运用上述仿真分析方法,对地下室侧墙柱(暗柱)间距、柱(暗柱)与墙体刚度比、构造钢筋、浇注长度、墙体厚度和模板六种因素逐一分析,从设计、构造、材料和施工入手,研究地下室侧墙混凝土温度裂缝的预防、控制问题,以供设计、施工人员参考。
Shrinkage compensation concrete (SCC) is an effective way to avoid shrinkage cracks of basement RC wall, which has been popularly used for cracking control in large buildings and extra long structures, but designing methods of SCC are still at the phase of experience and estimation. As a result, the indeterminacy and the reliability of the designing method are reduced and some SCC application in projects falls flat, that would restrict the generalization and application of the SCC undoubtedly. So developing more reasonable calculating method is an important research subject both having great significance in SCC theories and projects.
In this thesis, the principle of SCC would be introduced firstly. Then the thesis gave an introduction of shrinkage compensation patterns with small, moderate and absolute restrictions. Also the combined dry and cold shrinkage compensation patterns of mass concrete and large section concrete were obtained. Based on these theories, the approach of ultimate deformation and compressive strain of a basement SCC wall in Wuhan 30 days after casting was taken as an example.
Taking advantage of software ANSYS, the simulation analysis of the temperature field and the temperature stress field of the basement SCC wall mentioned before during construction period were achieved comprehensively. At the same time the relationship between interior and exterior restraints in this kind of structure and the temperature history effect on expansion simulation of SCC were studied too. Comparing the temperature stress results of simulation analysis with the empirical methods’, the former one can forecast the pre-pressing stress and crack resistant effect of the expansion agent more exactly in accordance with the distribution and variation disciplines of temperature stress in SCC wall. The SCC designed reasonably can prevent not only the shrinkage cracks during construction period effectively, but also the cracks brought by dry shrinkage during working life.
At last, this thesis compared six influencing factors on designing, structure, materials and construction, which are embedded column spacing, embedded column rigidity-wall rigidity ratio, construction bars, casting length, wall thickness and formwork materials. The research conclusions are very useful for temperature cracks preventing and controlling of the basement RC wall in designing and construction.
本文从补偿收缩混凝土的原理出发,介绍了在小限制、中等限制和大限制三类限制条件下的补偿收缩模式,建立了大体积、大截面混凝土冷缩和干缩联合补偿收缩模式。在此基础上,计算了武汉市某地下室侧墙混凝土30d最终变形,计算出膨胀剂在墙体中建立的压应变。
本文以ANSYS为平台,全面系统地实现该工程施工期间补偿收缩混凝土温度场和温度应力的仿真分析计算,研究了钢筋内约束与底板外约束之间的关系、探讨了考虑温度历程的补偿收缩混凝土的膨胀模拟的实现;根据地下室侧墙混凝土温度应力分布及变化规律,对掺入膨胀剂后墙体温度应力仿真结果与经验设计法计算结果进行比较,预测了膨胀剂建立的预压应力及抗裂效应。经合理设计的补偿收缩混凝土,能有效防止侧墙混凝土施工期收缩引起的裂缝,并能有效地预防墙体后期可能出现的干缩裂缝。
本文运用上述仿真分析方法,对地下室侧墙柱(暗柱)间距、柱(暗柱)与墙体刚度比、构造钢筋、浇注长度、墙体厚度和模板六种因素逐一分析,从设计、构造、材料和施工入手,研究地下室侧墙混凝土温度裂缝的预防、控制问题,以供设计、施工人员参考。
Shrinkage compensation concrete (SCC) is an effective way to avoid shrinkage cracks of basement RC wall, which has been popularly used for cracking control in large buildings and extra long structures, but designing methods of SCC are still at the phase of experience and estimation. As a result, the indeterminacy and the reliability of the designing method are reduced and some SCC application in projects falls flat, that would restrict the generalization and application of the SCC undoubtedly. So developing more reasonable calculating method is an important research subject both having great significance in SCC theories and projects.
In this thesis, the principle of SCC would be introduced firstly. Then the thesis gave an introduction of shrinkage compensation patterns with small, moderate and absolute restrictions. Also the combined dry and cold shrinkage compensation patterns of mass concrete and large section concrete were obtained. Based on these theories, the approach of ultimate deformation and compressive strain of a basement SCC wall in Wuhan 30 days after casting was taken as an example.
Taking advantage of software ANSYS, the simulation analysis of the temperature field and the temperature stress field of the basement SCC wall mentioned before during construction period were achieved comprehensively. At the same time the relationship between interior and exterior restraints in this kind of structure and the temperature history effect on expansion simulation of SCC were studied too. Comparing the temperature stress results of simulation analysis with the empirical methods’, the former one can forecast the pre-pressing stress and crack resistant effect of the expansion agent more exactly in accordance with the distribution and variation disciplines of temperature stress in SCC wall. The SCC designed reasonably can prevent not only the shrinkage cracks during construction period effectively, but also the cracks brought by dry shrinkage during working life.
At last, this thesis compared six influencing factors on designing, structure, materials and construction, which are embedded column spacing, embedded column rigidity-wall rigidity ratio, construction bars, casting length, wall thickness and formwork materials. The research conclusions are very useful for temperature cracks preventing and controlling of the basement RC wall in designing and construction.
引文
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[3] Vitharana,Nihal D.. Behavior of reinforced concrete reservoir wall elements under applied and thermally-induced loadings. ACI Structural Journal,1998.95(3): 238-248
[4] Majorana C.E.. Nonlinear analysis of thermal stresses in mass concrete castings. Cement and Concrete Research,1990.20(4):559-578
[5] Franz-Josef Ulm,Paul Acker,Michel Levy. The“Chunnel”Fire. II: Analysis of Concrete Damage. Engineering Mechanics,1999.125(3):283-289
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[11]张子明,郭兴文,杜荣强.水化热引起的大体积混凝土墙应力与开裂分析.河海大学学报,2002.30(5):12-16
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[27]朱伯芳.兼顾当前温度与历史温度效应的氧化镁混凝土双温计算模型.水利水电技术,2003.34(4):16-17
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[32] Ronaldo Luna,Yong Wu. Simulation of Temperature and Stress Fields During RCC Dam Construction. Construction Engineering and Management,2000. 126(5):381-388
[33] Franz-Josef Ulm,Olivier Coussy. What is a‘‘Massive’’Concrete Structure at Early Ages? Some Dimensional Arguments. Engineering Mechanics,2001.127(5): 512-522
[34] Zdenek P. Bazant,Jin-Keun Kim,Sang-Eun Jeon. Cohesive Fracturing and Stresses Caused by Hydration Heat in Massive Concrete Wall. Engineering Mechanics,2003.129(1):21-30
[35] Anna Saetta,Roberto Scotta,Renato Vitaliani. Stress Analysis of Concrete Structures Subjected to Variable Thermal Loads. Structure Engineering,1995. 121(3):446-457
[36] Yan-Zhou Niu,Chuan-Lin Tu,Robert Y. Liang etal. Modeling of Thermo- mechanical Damage of early-age concrete. Structure Engineering , 1995. 121(4):717-726
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[38]祝效华,余志祥.ANSYS高级工程有限元分析范例精选.北京:电子工业出版社,2004.33-43
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[56]李秀才.大体积混凝土开裂机理与仿真研究[硕士学位论文].武汉:武汉理工大学,2004
[2]游宝坤,李乃珍.膨胀剂及其补偿收缩混凝土.北京:中国建筑工业出版社, 2005.51-57
[3] Vitharana,Nihal D.. Behavior of reinforced concrete reservoir wall elements under applied and thermally-induced loadings. ACI Structural Journal,1998.95(3): 238-248
[4] Majorana C.E.. Nonlinear analysis of thermal stresses in mass concrete castings. Cement and Concrete Research,1990.20(4):559-578
[5] Franz-Josef Ulm,Paul Acker,Michel Levy. The“Chunnel”Fire. II: Analysis of Concrete Damage. Engineering Mechanics,1999.125(3):283-289
[6] Wilson E.L.. The Determination of Temperatures within Mass Concrete Structures. Structures and Materials Research,1968.68(4):158-169
[7] Tatro,Stephen B.,Ernest K.. Thermal Considerations for Roller Compacted Concrete. Journal of the American Concrete Institute,1985.82(3):286-299
[8]中华人民共和国国家标准.GB 50010-2002.混凝土结构设计规范.北京:中国建筑工业出版社
[9]林志海,覃维祖,张士海等.混凝土早期应力发展与抗裂性能评价.建筑技术,2003.34(1):34-35
[10]刘海成,宋玉普,吴智敏.考虑温度影响的大体积混凝土应力场分析方法.大连理工大学学报,2005.45(1):121-127
[11]张子明,郭兴文,杜荣强.水化热引起的大体积混凝土墙应力与开裂分析.河海大学学报,2002.30(5):12-16
[12]王润富,陈国荣.温度场和温度应力.北京:科学出版社,2005.46-73
[13]刘兴法.混凝土结构的温度应力分析.北京:人民交通出版社,1991.15-33
[14]朱伯芳.朱伯芳院士文选.北京:中国电力出版社,1997.431-495
[15]闫海华,李东,邹旭晖.某高层地下室剪力墙裂缝的有限元计算与分析.工业建筑,2004.34(12):48-52
[16]陈志明,管大庆.大型地下室墙板混凝土裂缝控制技术.建筑施工,1995. 17(4):10-12
[17]吴中伟,张鸿直.膨胀混凝土.北京:中国铁道出版社,1990.88-105
[18]游宝坤,颜亨吉,韩立林等.硅铝酸盐膨胀剂.中国,中文,ZL91110609,1993.12-20
[19]游宝坤.建筑物裂渗控制新技术.首届全国混凝土膨胀剂学术交流会论文集.北京:中国建材工业出版社,1994.122-148
[20]游宝坤.建筑物裂渗控制新技术.第二届全国混凝土膨胀剂学术交流会论文集.北京:中国建材工业出版社,1998.233-258
[21]游宝坤.混凝土膨胀剂及其应用.第三届全国混凝土膨胀剂学术交流会论文集.北京:中国建材工业出版社,2002.162-179
[22]中华人民共和国国家标准.GB 50119-2003.混凝土外加剂应用技术规范.北京:中国建筑工业出版社
[23]中华人民共和国建材行业标准.JC 476-2001.混凝土膨胀剂.北京:中国建材工业出版社
[24]叶亮.补偿收缩混凝土在受基础约束钢筋混凝土墙中的控裂效能评价[硕士学位论文].杭州:浙江大学,2004
[25]朱伯芳.微膨胀混凝土自身体积变形的增量型计算模型.水利发电, 2003.29(2):20-23
[26]朱伯芳.微膨胀混凝土自生体积变形的计算模型和试验方法.水利学报, 2002.33(12):18-21
[27]朱伯芳.兼顾当前温度与历史温度效应的氧化镁混凝土双温计算模型.水利水电技术,2003.34(4):16-17
[28]张国新.考虑温度过程效应的MgO微膨胀热积模型.水力发电,2002.29(11):28-32
[29]张国新,陈显明,杜丽惠.氧化镁混凝土膨胀的动力学模型.水利水电技术, 2004.35(9):88-91
[30]张国新,陈显明,杜丽惠.掺氧化镁混凝土的膨胀效果分析.水利学报,2005. 36(2):185-189
[31]张国新,金峰,罗小青等.考虑温度历程效应的氧化镁微膨胀混凝土仿真分析模型.水利学报,2002.33(8):29-34
[32] Ronaldo Luna,Yong Wu. Simulation of Temperature and Stress Fields During RCC Dam Construction. Construction Engineering and Management,2000. 126(5):381-388
[33] Franz-Josef Ulm,Olivier Coussy. What is a‘‘Massive’’Concrete Structure at Early Ages? Some Dimensional Arguments. Engineering Mechanics,2001.127(5): 512-522
[34] Zdenek P. Bazant,Jin-Keun Kim,Sang-Eun Jeon. Cohesive Fracturing and Stresses Caused by Hydration Heat in Massive Concrete Wall. Engineering Mechanics,2003.129(1):21-30
[35] Anna Saetta,Roberto Scotta,Renato Vitaliani. Stress Analysis of Concrete Structures Subjected to Variable Thermal Loads. Structure Engineering,1995. 121(3):446-457
[36] Yan-Zhou Niu,Chuan-Lin Tu,Robert Y. Liang etal. Modeling of Thermo- mechanical Damage of early-age concrete. Structure Engineering , 1995. 121(4):717-726
[37]张敏玉,文立华,王卫祥.混凝土浇注过程的数值仿真.低温建筑技术, 2005.(2):32-33
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