Wilding Bastian Valentin, Godio Michele, Beyer Katrin
Laboratory of Earthquake Engineering and Structural Dynamics (EESD), School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), EPFL ENAC IIC EESD, GC B2 495, Station 18, 1015 Lausanne, Switzerland.
Mater Struct. 2020;53(2):40. doi: 10.1617/s11527-020-01464-1. Epub 2020 Apr 15.
When designing unreinforced masonry buildings, the wall stiffness and, consequently, the masonry elastic and shear modulus and are essential parameters. Current codes provide empirical estimates of the masonry elastic modulus and a ratio between the shear and elastic modulus, /. This ratio, commonly taken as 0.4, is not based on scientific evidence and there appears to be no consensus concerning its value and influencing parameters, meaning that current code standards might not accurately portray the shear deformations of masonry elements. To give the choice of the ratio a theoretical foundation, this paper presents closed-form expressions for the ratio of running-bond masonry that capture the effects of finite joint thickness, finite wall thickness and orthotropic block properties. Based on the geometry of blocks and joints as well as their elastic parameters, a validation of the developed expression using 3D finite element analyses shows good performance. For modern masonry typologies with hollow clay bricks, a / ratio of 0.20-0.25 is obtained. For historical masonry typologies, such as dry stacked or mortared stone masonry, as well as solid clay brick masonry, ratios between 0.30 and 0.40 are computed.
在设计无筋砌体建筑时，墙体刚度以及砌体的弹性模量和剪切模量是至关重要的参数。现行规范提供了砌体弹性模量的经验估计值以及剪切模量与弹性模量的比值 / 。这个通常取值为0.4的比值并非基于科学依据，而且对于其数值和影响参数似乎没有达成共识，这意味着现行规范标准可能无法准确描述砌体构件的剪切变形。为了给比值 的选择提供理论基础，本文给出了顺砌砌体比值的封闭形式表达式，该表达式考虑了有限的灰缝厚度、有限的墙体厚度和正交各向异性砌块特性的影响。基于砌块和灰缝的几何形状及其弹性参数，通过三维有限元分析对所推导表达式进行验证，结果显示性能良好。对于采用空心粘土砖的现代砌体类型，得到的 / 比值为0.20 - 0.25。对于历史砌体类型，如干砌或浆砌石砌体以及实心粘土砖砌体，计算得到的比值在0.30至0.40之间。
