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91.
混凝土结构(构件)裂缝在混凝土结构中是常见的,混凝土的正常使用状态本身就是带裂缝工作的状态。出现裂缝后,就要分析哪些裂缝是有害裂缝,哪些是无害裂缝,经分析后,才能针对不同的裂缝进行针对处理。结合工作实践,从常见的裂缝产生原因入手。在混凝土裂缝的防治及施工方面注意的问题等方面,作一探讨。 相似文献
92.
通过对几种不同宽跨比整体式钢筋混凝土简支板桥的ANSYS有限元实体分析,总结出了这类板桥纵向贯通裂缝形成的主要原因。提出在整体式钢筋混凝土简支板桥的设计中,在满足纵向配筋要求的同时,必须增加横向配筋的数量来抵抗不得忽视的横向内力,以防止板桥出现纵向贯通裂缝。 相似文献
93.
Contact-induced Damage in Ceramic Coatings on Compliant Substrates: Fracture Mechanics and Design 总被引:2,自引:0,他引:2
Young-Woo Rhee Hae-Won Kim Yan Deng Brian R. Lawn 《Journal of the American Ceramic Society》2001,84(5):1066-1072
Simple explicit relations are presented for the onset of competing fracture modes in ceramic coatings on compliant substrates from Hertzian-like contacts. Special attention is given to a deleterious mode of radial cracking that initiates at the lower coating surface beneath the contact, in addition to traditional cone cracking and quasiplasticity in the near-contact area. The critical load relations are expressed in terms of well-documented material parameters (elastic modulus, toughness, hardness, and strength) and geometrical parameters (coating thickness and sphere radius). Data from selected glass, Al2 O3 and ZrO2 coating materials on polycarbonate substrates are used to demonstrate the validity of the relations. The formulation provides a basis for designing ceramic coatings with optimum damage resistance. 相似文献
94.
Robert Gracie Ted Belytschko 《International journal for numerical methods in engineering》2009,78(3):354-378
A method for the modeling of dislocations and cracks by atomistic/continuum models is described. The methodology combines the extended finite element method with the bridging domain method (BDM). The former is used to model crack surfaces and slip planes in the continuum, whereas the BDM is used to link the atomistic models with the continuum. The BDM is an overlapping domain decomposition method in which the atomistic and continuum energies are blended so that their contributions decay to their boundaries on the overlapping subdomain. Compatibility between the continua and atomistic domains is enforced by a continuous Lagrange multiplier field. The methodology allows for simulations with atomistic resolution near crack fronts and dislocation cores while retaining a continuum model in the remaining part of the domain and so a large reduction in the number of atoms is possible. It is applied to the modeling of cracks and dislocations in graphene sheets. Energies and energy distributions compare very well with direct numerical simulations by strictly atomistic models. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
95.
Wei Chen Doru C. Lupascu Jürgen Rödel Christopher S. Lynch 《Journal of the American Ceramic Society》2001,84(3):593-597
This work describes the measurement of R -curve behavior in ferroelectric ceramics using four-point bend specimens with controlled semielliptical surface cracks. The results are compared for two compositions of lead lanthanum zirconate titanate. One exhibits ferroelastic behavior, the other electrostrictive linear elastic behavior. R -curves are measured in the crack length regime of 0.1 to 0.8 mm. The ferroelastic composition displays a toughness increase from 0.5 to 1.2 MPa·m1/2 . The linear elastic composition displays a flat R -curve. The R -curve behavior is attributed to ferroelastic toughening. 相似文献
96.
对钢筋混凝土现浇板裂缝的种类和特点及产生的原因进行了总结,指出影响裂缝产生的多方面的因素,并提出了防止裂缝的相应措施和加固方法,以期指导实践。 相似文献
97.
Life assessment of structures weakened by interacting cracks represents an important and very challenging problem. Subsequently, the main objective of this paper is to address this problem by developing a new computational technique. It is based on the classical strip-yield model and plasticity-induced crack closure concept. It also utilises the 3D fundamental solution for an edge dislocation. The crack advance scheme adopts the cycle-by-cycle calculations of the effective stress intensity factors and crack increments. The modelling results are validated against an experimental study focusing on fatigue behaviour of two closely spaced collinear cracks in wide plates with different thicknesses. It is confirmed that non-linear effects associated with crack interaction have a significant influence on fatigue life and cannot be disregarded in life and integrity assessments of structural components. 相似文献
98.
地下室剪力墙裂缝问题频发,不仅影响了美观,并且严重影响了地下室结构的受力性能。本文将结合实例,对地下室剪力墙裂缝问题进行了分析,找出了问题并提出了解决方案。 相似文献
99.
100.
以某厂工字形带裂缝的钢吊车梁为研究对象,在对国内外开裂钢吊车梁疲劳损伤进行广泛调查研究的基础上,提出了以提高吊车梁上部区域有效面积和刚度为目的的加固方案.通过吊车梁加固前后200万次疲劳试验,对加固前后裂缝尖端主应力的大小及方向的变化规律进行了研究.研究结果表明:通过增大截面有效面积及刚度可以延长开裂钢吊车梁的疲劳剩余使用寿命,对实际工业厂房中存在开裂的钢吊车梁的加固及维护有很好的指导意义. 相似文献