Igor Araújo, Joel Araújo do Nascimento Neto and Guilherme Aris Parsekian
Igor Araújo, Civil Engineer, Federal University of Rio Grande do Norte, 3000 Senador Salgado Filho Avenue., Natal, RN, Brazil, igorrraraujo@hotmail.com
Joel Araújo do Nascimento Neto, Professor of the Department of Civil Engineering, Federal University of Rio Grande do Norte, 3000 Senador Salgado Filho Avenue., Natal, RN, Brazil, joel.nascimento@gmail.com
Guilherme Aris Parsekian, Associate Professor, Department of Civil Engineering, Federal University of Sao Carlos, Rod. Washington Luiz, km 235, São Carlos, SP, Brazil, parsekian.ufscar@gmail.com.
ABSTRACT
Slender walls and columns have lower capacity to carry loads due to lateral deflections. In order to cover slenderness effects in masonry structures, an additional eccentricity is added to the vertical load eccentricity as presented in BS 5628-1:2005. Capacity reduction factor (CRF) is used to determine the compressive strength of masonry walls and columns in terms of slenderness ratio and eccentricity of load. It can be derived by assuming that the stress is uniformly distributed along the compressive zone. However, the equations to calculate the CRF given in the British Standard (BS 5628-1) for single wythe walls only deals with solid section walls. Then, the CRF of four different hollow cross sections were determined. The local second order effects were considered in the design of the masonry walls following the recommendations given in the British (BS 5628-1:2005) and Brazilian (NBR 15961-1:2011) standards. It was noticed that the required strength increased significantly, meaning that it is important to consider these effects in the design. Large masonry shear walls of the ground floor of an actual multistory building were divided in equal parts and analyzed as individual columns, similarly to the Brazilian Concrete Code (NBR 6118:2014) procedure. The geometry and loading data of the shear walls have been taken from the structural design of the building, which was calculated using the Brazilian software TQS for masonry building design. No modelling was performed, only simplified analysis on mid span cross sections of the wall associated to the largest transverse displacement. It was evaluated the increase in the required compressive strength of the walls when the second order bending moments due to slenderness are taken in account.
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