In order to explore this baffling problem and to crack down on it , this article explains initially how the cracks in cast - in - situ concrete floor come from . based on research in many project samples , the cracks - forming reasons come to three aspects : design , construction and materials . this essay is a systematic summary of different forming reasons and their counterpart precautions , an introduction of treating methods for formed cracks and a detailed analysis come along side project samples 为了深入探讨这一困扰工程界的难题，解决这一问题，本文首先对混凝土结构裂缝产生的机理进行了阐述，对大量的工程实例的裂缝进行了调研，并在此基础上，将产生裂缝的原因归纳为：设计、施工和材料等三个方面，对不同原因及其预防措施给予了系统全面的总结，介绍了对已形成裂缝的处理措施，并结合工程实例给予了详细的分析。
As a sub - topic of " cracking mechanism and a whole set of control technique of modern concrete , structure " ( no : 50278031 ) supported by national natural science foundation , this paper studies ail - roundly and systematically temperature crack controlling technique of basement wall of high - rise building and puts forward the solution methods into the theoretical calculation and construction practice 本文作为国家自然科学基金“现代混凝土结构裂缝机理及成套控制技术” (编号： 50278031 )的子题之一，对此问题进行了全面的、系统的研究，从理论计算和施工实践两方面提出了解决方案。
Second , on the basis of the elastic theories , discussed the reason of the temperature stress in the big block reinforced technique and the calculation method of the health diagnosis technique , and how to control the crack of temperature stress is discussed completely and systematically in the paper 其次，本文在弹性理论的基础上，论述了大体积混凝土结构温度应力产生的原因及计算方法，结合实际工程，全面系统地论述了大体积混凝土结构裂缝的健康诊断技术以及如何控制因温度应力产生的裂缝。
The first part of this thesis brings forward the normal procedure of bridge construction crack analysis , briefly makes an argument about the crack control standard at home or abroad , analyses some questions on crack , states the experiment analysis of crack controlling by using steel fibre reinforced concrete ( sfrc ) 本文上篇，提出了桥梁结构裂缝分析的一般步骤，简要地评论了国内外现有裂缝控制准则；探讨了裂缝的有关问题；对裂缝产生的机理进行了分析；阐述了钢纤维混凝土限裂实验研究。
In the process of building and using the mass concrete structures , because of the effect of out - side condition and themselves , some faults will form in the structure , these faults will effect the bearing capability and endurance using nondestructive testing method to test the concrete ' s quality and diagnose its healthy , which has the significant sense in assessing the safety stability and research of the administering diseases this dissertation mostly researched the testing methods in the mass concrete structure , discussed the principles , methods , features , sphere of application of the ultrasonic testing in the mass concrete structure with faults , used dynamic fem to simulate the testing process , discussed when the concrete structure with cracks is under the effect of the pulse , how the elastic waves propagate and what are their changing feature , researched the principles of the first - arriving waves " phase when the cracks " depths are not same , obtained the relation between the inversion point and the cracks " depth , which has the direction sense in the application of projects , the second part of this dissertation is ct , which used the ultrasonic wave running through the tested - substance to get arriving - time of the ultrasonic wave , then inverse the image this dissertation drawed one ct program which can well present the different little cells " ultrasonic wave velocity profiles of the substance , thereby to diagnose the quality of the part of the tested - substance , ct has the better using foreground . 在混凝土结构的施工及使用过程中，由于受其自身及外界各种因素的影响，常常会产生一些缺陷，对结构物的承载能力和耐久性造成严重影响，采用无损检测技术进行质量检测和健康诊断，这对混凝土结构开展安全、稳定性评估以及病害隐患治理研究具有重要意义。本论文主要针对大体积混凝土结构缺陷的检测方法展开研究工作，重点讨论了超声波法检测混凝土结构裂缝的基本原理和方法及其特点、适用范围，运用动力有限元数值模拟其检测过程，探讨了有裂缝缺陷的混凝土结构在脉冲荷载作用下弹性波的传播及其变化特征，研究了不同裂缝深度下首波相位变化规律，得出了反转临界点与裂缝深度之间的关系，这对实际工程应用具有指导意义。声波ct是一种新的无损检测技术，它是利用声波穿透被检测体获取声波接收时间，来进行计算机反演成像的技术。
Because concrete crack will greatly affect the security of concrete penstock in hydropower station , the paper applies the theory of global optimization method to predict the maximum concrete crack width in steel - lined reinforced concrete penstock and bring forward a predicting model based on the theory of artificial neural network ( ann ) 摘要基于人工神经网络的全局优化方法的基本理论，对钢衬钢筋混凝土压力管道外包混凝土结构裂缝预测进行了研究，提出了基于神经网络的管道混凝土裂缝预测模型。
Also , following article is a combination of structure cracks theory and practice ; a thorough analysis of structure cracks , frequently appeared but often omitted problems . thus , this essay is of realistic value to instruct construction and avoid the cracks in cast - in - situ 本文的确定工作将有关工程结构裂缝理论和工作实践相结合，对设计和施工中经常出现的又是常被忽视的工程结构裂缝因素进行了较为透彻的分析，对于编制工程结构抗裂方案、指导施工、避免现浇混凝土楼板裂缝的产生，具有现实的意义。
( 3 ) stress field of cast - in - place slab with large - area has been calculated , the stress rule and the stress characteristics of cast - in - place slab with large - area subjected to all kinds of temperature effect have been summarized . ( 4 ) sensibility of the influence of factors of temperature field and stress field has been analyzed . ( 5 ) the methods to control crack of cast - in - place slab with large - area in several aspects , such as frame design concrete material and construction techniques are summed up 主要进行了以下几个方面的工作： ( 1 )探讨了大面积现浇楼盖结构温度裂缝出现的机理，总结归纳了常见裂缝的种类； ( 2 )对大面积现浇楼盖结构施工期温度场进行了仿真分析； ( 3 )对施工期和正常使用期大面积现浇楼盖结构在温度作用下的内力进行了计算分析，总结归纳了各种温度作用下大面积现浇楼盖结构内力分布规律和特点； ( 4 )对影响大面积现浇楼盖结构温度场和温度应力的因素进行了敏感性分析； ( 5 )从结构设计、混凝土材料、施工工艺等几方面总结大面积现浇楼盖结构裂缝控制的方法； ( 6 )用工程实例验证裂缝控制措施的有效性。
A 1 / 7 - scale model of three - bay , three - span frame - bent r . c . structure is the first and the largest size in the same testing field in china by now . following studies are chiefly conducted in this chapter : the mechanism behavior of the structure under horizontal earthquake load , including the characteristics of seismic force , the deformed performance , yielding sequence , energy dissipation capacity etc . ; the changing rule of the dynamic characteristics and the stiff degrading in different experimental stages ; the location of the weak stories and the seismic capacity of the structure 在试验中主要研究了以下内容：在水平力作用下框排架结构的整体变形能力以及各层的层间变形的大小；框排架结构在不同阶段的动力变化规律；框排架柱的变形和承载能力；错层对结构性能的影响、模型结构裂缝开展过程及塑性铰形成的先后顺序、不同阶段该结构的刚度退化规律及滞回耗能特性等。
Secondly , the producing mechanism of crack in reinforced structure and factors which affect crack have been discussed , in the emphasis , the method is expounded , which applies first releasing then resisting , combination of releasing and resisting . in the method , flexible slit is applied firstly , which can make deformation of structure distributed , and decrease deformation energy , then the tiny expansion concrete and prestressed concrete with unbonded tendons are applied . and in the different phase , the compressive prestress is put on the concrete structure 其次，分析并论述了钢筋混凝土结构裂缝产生的机理和影响因素，着重阐述了“利用先放后抗，抗放结合，综合控制”的方法：即首先利用后浇带，使混凝土结构分段变形，减小超长变形的影响；并采用微膨胀混凝土技术及无粘结预应力混凝土技术，分阶段对混凝土结构施加一定的预压应力，从而减小或完全抵消混凝土结构因混凝土硬化收缩引起的拉应力；再结合一些其他措施，成功实现钢筋混凝土结构的超长无缝设计与施工。
