【作者】 黄科锋；

【导师】 刘西拉；

【作者基本信息】 上海交通大学 ， 结构工程， 2014， 博士

【摘要】 钢筋混凝土结构在施工阶段实际上是一个部分完成的结构和模板支撑系统构成的“时变结构”。经验表明，随着模板支撑系统的撤换这种结构很可能出现在整个“生命周期”中最不安全的受力状态，从而引发事故。为了控制这种事故的发生，自上个世纪60年代开始国内外做了大量的研究，探索了一些便于施工安全控制的简明的计算方法。美国学者P. Grundy和A. Kabaila提出了简化手算结构分析方法，此后，我国学者刘西拉教授于1985年建立了施工期结构分析的三维有限元法——精化方法。简化方法和精化方法是钢筋混凝土结构施工期荷载传递研究中的两个里程碑式的计算模型。随着现代施工技术的不断提高，钢支撑在钢筋混凝土结构施工中逐渐取代了木支撑得到了越来越广泛的使用。而一些实测研究表明，钢支撑在昼夜温差作用下热胀冷缩对施工期结构荷载传递的影响不能被忽略。为了研究温差对施工期钢筋混凝土结构荷载传递的影响规律，本文作了如下研究工作。首先，在结构模型方面，本文在国内外相关研究的基础上，增加考虑施工日夜环境温差的影响，统一了现有的钢筋混凝土框架，板柱和墙板结构在施工期的结构模型和分析方法，模型考虑了混凝土强度和弹性模量随龄期增长的影响。接着本文使用二维非稳态热传导方程建立了昼夜温差和钢支撑同混凝土结构柱子之间的温差的相互关系，并据此将温度的影响以广义的荷载添加到结构中。同时，本文还在模型中考虑了钢支撑上下木垫块引起支撑整体抗压刚度的影响。其次，本文根据前面的结构模型和温度模型编制了相应的“考虑温度影响的施工过程安全分析”（Safety Analysis during Construction consideringTemperature，SACT）应用软件。SACT能运行于windows2000，window XP，windows7等多个操作系统，可使用Excel2000，Excel2003，Excel2007，Excel2010等多个版本进行数据输入和输出。SACT采用MFC（Microsoft FoundationClasses）应用程序框架编写图形界面，能进行施工操作的逐步模拟和计算。SACT软件在编制过程中体现了模型中所考虑的温差以及钢支撑上下木垫块对施工期荷载传递的影响。通过同现场实测数据的比较验证了SACT计算结果的准确性和适用性。此外，文章还讨论了温差大小对施工期荷载传递的影响，揭示了不同昼夜温差影响下的钢筋混凝土结构施工期荷载传递规律，并建议了临界温差值，当昼夜温差大与临界温差时，温差对荷载传递的影响不应被忽略。最后，本论文还分析讨论了在温度影响下施工周期，钢支撑层数以及支撑刚度（木垫块厚度）对施工期混凝土结构荷载传递的影响，分析并得出了一些相关规律，提出了提高施工安全性的一些改进措施。这些结论对现场施工人员有一定的借鉴意义。更多还原

【Abstract】 The reinforced concrete structure during construction is a time-dependent struc-ture which consists of a partly completed structure and a formwork shore system. Ex-perienceshowsthat，astheformworkshoresystemchanges，thetime-dependentstruc-ture may be under the most vulnerable stress state in its”lifetime” and accidents mayoccur. Since1960researchers all over the world have done a lot of researches andexplored some concise and practical calculation methods for construction safety con-trol. P. Grundy and A. Kabaila proposed a simplifed method which is easy to apply.Later in1985Xila Liu presented a three-dimensional fnite element method for struc-tures during construction—a refned method. The simplifed method and the refnedmethod are two ground-breaking methods for analyzing the load transfer in reinforcedconcrete structures during construction.With the development of construction techniques, steel supports are more andmorewidelyusedandgraduallyreplacingtimberingsupports. Experimentshaveshownthat,theefectofexpansionandcontractionofsteelsupportsontheloadtransferduringconstruction caused by daily temperature variation can not be neglected.In order to study infuences of temperature variation on the load transfer, the mainwork can be summarized as follows.At frst, existing structural analysis methods for reinforced concrete frames, slab- column systems, and wall slab structures are unifed based on related researches. Dur-ing analysis, the two-dimensional unsteady heat conduction equation is used to cal-culate the temperature diference between steel shores and concrete columns causedby daily temperature variation, and the efect of temperature variation is considered asa generalized load acting on structures. During analysis, the efects of wood blocksat both ends of steel shore are also considered while calculating the stifness of steelshores.Then a new software named Safety Analysis during Construction consideringTemperature (SACT) is programmed based on proposed structural model and analysismethods. SACT can run under operation systems such as windows2000, windows XP,and windows7, and multiple versions of Excel such as Excel2000, Excel2003, Excel2007, and Excel2010can be used for data input and output. The graphic interfaceis programmed using MFC application. SACT can simulate and calculate structuresduring construction step-by-step. The efect of temperature variation and the infuenceof wood blocks at both ends of steel shores are all taken into account while calculatingthe load transfer by SACT. The software is proved to be accurate and applicable bycomparing with feld test data.Efects of temperature variation on the load transfer during construction are alsodiscussed in the present paper. The load transfer pattern under the infuence of tem-perature is obtained and the critical temperature variation is proposed. If the ambienttemperaturevariationbetweendayandnightislargerthanthecriticaltemperaturevari-ation, the efects of temperature variation can not be neglected.Finally, efectsoftheconstructionperiod, layersofsteelshoresandthestifnessofsupports (the thickness of wood blocks) on the load transfer during construction underthe infuence of temperature are analyzed as well. Based on these analyses, relatedpatterns have been concluded and improvement measures for construction safety areproposed. These conclusions are signifcant for on-site construction personnel.更多还原