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DESIGN OF MASONRY STRUCTURES Part 4

Lý thuyết độ bền vật liệu (ví dụ lý thiết đàn hồi - elasticity, lý thuyết chảy - plasticity) cũng thuộc về kết cấu xây dựng. Kết cấu xây dựng là cơ sở cho việc thiết kế công trình trong trạng thới giới hạn độ bền (ultra limit states - ULS) và trạng thái giới hạn sử dụng (serviceability limit states - SLS). | Table 4.7 Values of fvk0 and limiting values offvk for general-purpose mortar EC6 a Masonry unit Mortar vk0 N mm2 Limiting fvk N mm2 Group 1 clay units MIO to M20 M2.5 to M9 Ml to M2 Group 1 units other MIO to M20 than clay and natural M2.5 to M9 stone Ml to M2 Group 1 natural stone M2.5 to M9 units Ml to M2 Group 2a clay units MIO to M20 Group 2a and Group M2.5 to M9 Ml to M2 MIO to M20 2b units other than M2.5 to M9 clay and Group 2b clay units Ml to M2 Group 3 clay units MIO to M20 02 0.1 0.2 0.15 0.1 M2.5 to M9 Ml to M2 TO 1.0 The lesser of longitudinal compressive or ÕTỊ Ton 0.3 02 0.1 No limits other than given by equation 3.4 of EC6 aFor Group 2a and 2b masonry units the longitudinal compressive strength of the units is taken to be the measured strength with Ồ taken to be not greater than 1.0. When the longitudinal compressive strength can be expected to be greater than 0.15 fb by consideration of the pattern of holes tests are not necessary. f Deformation properties of masonry It is stated that the stress-strain relationship for masonry is parabolic in form but may for design purposes be assumed as an approximation to be rectangular or parabolic-rectangular. The latter is a borrowing from reinforced concrete practice and may not be applicable to all kinds of masonry. The modulus of elasticity to be assumed is the secant modulus at the serviceability limit i.e. at one-third of the maximum load. Where the results of tests in accordance with the relevant European standard are not available E under service conditions and for use in structural analysis may be taken as 1000fk. It is further recommended that the E value should be multiplied by a factor of 0.6 when used in determining the serviceability limit state. A reduced E value is also to be adopted in relation to long-term loads. This may be estimated with reference to creep data. In the absence of more precise data the shear modulus may be assumed to be 40 of E. 2004 Taylor Francis g Creep shrinkage and .