Seismic capacity of irregular unreinforced masonry walls with openings

Masonry buildings are often characterized by geometric irregularities. In many cases, such buildings meet global regularity requirements provided by seismic codes, but they are composed by irregular walls with openings. The latter are masonry walls characterized by (i) openings of different sizes, (ii) openings misaligned in the horizontal and/or vertical direction, or (iii) a variable number of openings per story. An irregular layout of openings can induce not only a nonuniform distribution of gravity loads among masonry piers but also unfavorable damage localizations resulting in a premature collapse of the wall and hence a higher seismic vulnerability. This paper is aimed at providing a simplified methodology to assess the effects of irregularities on the in-plane seismic capacity of unreinforced masonry (URM) walls with openings. To this end, a macroelement method was developed and validated through experimental results available in the literature. The proposed methodology was based on the quantification of wall irregularities by means of geometric indices and their effects on seismic capacity of URM walls with openings through both sensitivity and regression analyses. Sensitivity analysis was based on a high number of static pushover analyses and allowed to assess variations in key seismic capacity parameters. Regression analysis let to describe each capacity parameter under varying irregularity index, providing empirical models for seismic assessment of irregular URM walls with openings. The in-plane seismic capacity was found to be significantly affected by wall irregularities, especially in the case of openings with different heights

Experimental seismic performance assessment of asymmetric masonry buildings

This paper presents the experimental validation and analyses of a structural constructive system based on concrete block masonry. The system has been proposed as an innovative solution for the construction of residential buildings. In the present study, an asymmetric configuration for the masonry buildings tested at the shaking table was adopted, being considered two buildings (reinforced and unreinforced). The seismic performance of both buildings is evaluated based on global and relative displacements, global damage patterns and failure mechanisms. Additionally, a comparison of the mechanical performance between the two buildings is also provided. Both structures were tested to "near collapse" condition from which it was found the influence of the geometrical configuration and the presence of steel reinforcement.The reinforced building attained an input acceleration twice the unreinforced building on the weak direction. The structure developed important in-plane and out-of-plane damage mainly at the first level including detachment of units, structural components (wall to wall) and failure of horizontal reinforcement. On the other hand, the damage observed on the unreinforced building was more distributed along the height of the building, is characterized for lower detachment of units but for a clear sliding mechanism at the second level along the cracks at the bed joints.The authors acknowledge to the Portuguese Agency of Innovation (ADI), which financed the present work developed in the scope of the national project ALVEST (no5456), "Development of solutions for structural masonry".info:eu-repo/semantics/publishedVersio

Masonry mechanical properties

Different approaches can be followed for numerical modeling of masonry and historical structures. Depending on the modeling strategy and level of complexity involved, a set of input parameters related to linear and nonlinear properties of units and mortar or masonry is required that, ideally, should be obtained experimentally.- (undefined

Nonlinear Structural Performance of a Historical Brick Masonry Inverted Dome

Traditional domes are obtained by double curvature shells, which can be rotationally formed by any curved geometrical plane figure rotating about a central vertical axis. They are self-supported and stabilized by the force of gravity acting on their weight to hold them in compression. However, the behavior of inverted domes is different since the dome is downward and masonry inverted domes and their structural behaviors in the literature received limited attention. This article presents a nonlinear finite element analysis of historical brick masonry inverted domes under static and seismic loads. The brick masonry inverted dome in the tomb of scholar Ahmed-El Cezeri, town of Cizre, Turkey, constructed in 1508 is selected as an application. First, a detailed literature review on the masonry domes is given and the selected inverted dome is described briefly. 3D solid and continuum finite element models of the inverted masonry dome are obtained from the surveys. An isotropic Concrete Damage Plasticity (CDP) material model adjusted to masonry structures with the same tensile strength assumed along the parallel and meridian directions of the inverted dome is considered. The nonlinear static analyses and a parametric study by changing the mechanical properties of the brick unit of the inverted masonry dome are performed under gravity loads. The acceleration records of vertical and horizontal components of May 1, 2003 Bingol earthquake (Mw = 6.4), Turkey, occurred near the region, are chosen for the nonlinear seismic analyses. Nonlinear step by step seismic analyses of the inverted dome are implemented under the vertical and horizontal components of the earthquake, separately. Static modal and seismic responses of the inverted masonry dome are evaluated using mode shapes, minimum and maximum principal strains and stresses, and damage propagations