Serviceability limit state related to excessive lateral deformations to account for infill walls in the structural model

Abstract

Brazilian Codes NBR 6118 and NBR 15575 provide practical values for interstory drift limits applied to conventional modeling in order to prevent negative effects in masonry infill walls caused by excessive lateral deformability, however these codes do not account for infill walls in the structural model. The inclusion of infill walls in the proposed model allows for a quantitative evaluation of structural stresses in these walls and an assessment of cracking in these elements (sliding shear diagonal tension and diagonal compression cracking). This paper presents the results of simulations of single-story one-bay infilled R/C frames. The main objective is to show how to check the serviceability limit states under lateral loads when the infill walls are included in the modeling. The results of numerical simulations allowed for an evaluation of stresses and the probable cracking pattern in infill walls. The results also allowed an identification of some advantages and limitations of the NBR 6118 practical procedure based on interstory drift limits.

Seismic analysis of reinforced concrete buildings with participating masonry infills

“…In turn, as demonstrated in Doudoumis [24] and Asteris et al [60], the modeling via FEM with finite elements for plane stress and material linear analysis can be useful in different situations, such as the verification of more simplified models, also serving to measure the expressions proposed for determining the equivalent diagonal width. This type of modeling was used more recently in investigations by Silva [2], Alva et al [1], Montandon [50], Alva and Montandon [3], and will be touched upon in Section 4.2.3.…”

“…For a more refined modeling, numerical simulations with two-dimensional finite elements were performed, considering a plane stress (FEM-PS), including the contact problem between participating masonry and concrete frame. The numerical modeling described in this Section is demonstrated with more details in Silva [2], Alva et al [1], Montandon [50] and Alva and Montandon [3].…”

“…These values were estimated based on current Brazilian structural masonry codes, assuming that the maximum possible stress at the wall-frame interface is the masonry shear strength. Figure 4a illustrates one of the models investigated by Alva et al [1] for a single-story infilled frame, with details of the discretization used, the deformed shape and the field of compressive principal strains. Figure 4b illustrates the model used in this paper for the 12-story frame.…”

“…In Brazil, structural designs usually disregard infill masonry walls in the structural model, although their inclusion may provide important information regarding the cracking states of walls due to excessive lateral deflection of buildings -Alva et al [1], Silva [2], Alva and Montandon [3] -and better accuracy in assessments of human comfort and wind dynamic effects in tall buildings. Noteworthy here is that in Brazil there is currently no code in force dealing with infill masonry walls with a structural function in frame buildings.…”

Influência das alvenarias de preenchimento na determinação do período fundamental de edifícios de concreto armado

“…Para edifícios de concreto mais altos, as alvenarias de preenchimento apresentam uma boa contribuição para a rigidez global da estrutura frente às ações horizontais (MONTANDON, 2018). Ao mesmo tempo, a consideração da alvenaria no modelo estrutural pode deflagrar possíveis rupturas da parede (compressão, tração e cisalhamento) em verificações do estado limite de serviço conforme demonstrado nos trabalhos de Alva et al (2015) e Montandon (2018).…”