Analytical and Experimental Study on Slender Structural Masonry Walls

• Grant number: 11/14813-8
• Support Opportunities: Scholarships in Brazil - Master
• Start date: March 01, 2012
• End date: February 28, 2014
• Field of knowledge: Engineering - Civil Engineering - Structural Engineering
• Principal Investigator: Guilherme Aris Parsekian
• Grantee: Guilherme Martins Lopes
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

The compressive strength is the main property of a masonry structure, since the vast majority of structural elements in this type of construction system are subjected to compressive stress predominated. One of the factors to be taken into account in the design of compressed elements is the slenderness of this element. Even today in Brazil uses the concept of slenderness simplified, where the buckling length is determined by an effective height (hef) and the radius of gyration is replaced by a parameter called effective thickness (teff) to calculate minority of resistance factor. This factor has its origin in standards and international building codes very old, dating back to times when these codes dealt with the scaling of the allowable stress method, having been lost and therefore it is unknown effective explanation of their deduction. With the various updates of international standards in structural masonry and the consequent adoption of the method for scaling limits of the States, this factor was abolished. In Brazilian standards, even with the adoption of the method of limit states, this factor remains in force, which leads to a contradiction. Studies on the effect of reduced resistance due to slenderness show that there are large differences in results when comparing the simplified method in NBR with other international standards. These differences probably do not induce the loss of national security structures because the slenderness ratio has been limited to low values, especially in the case of masonry unarmed. Within this context, the objective of this study is to perform theoretical and experimental study to allow an evolution in consideration of slenderness in structural masonry walls, eliminating the rough today and simplistic account of existing standards in Brazil, for an analytical procedure. A large gain can result from technical criteria for adoption of more accurate sizing compression: the Brazilian standardization may effectively be a procedure based on ultimate limit state with accurate determination of the criteria for sizing and standard comparable to international standards; The reductions may be cleared of resistance based on consistent experimental program, conducted with Brazilian materials and in compliance with usual practice of construction adopted in Brazil; Is it possible to perform the scaling of walls with slenderness ratio greater than the current limits, common cases in several buildings, including commercial buildings and industrial lands of the usual high-ceilinged (warehouses, supermarkets, shopping malls, sporting arenas, among others), single-storey housing block with thin and often without locking top, residential buildings with double height; Using the simplified table for determining the effective thickness of walls with stiffeners (source of several design errors in the last two decades) becomes unnecessary; Allow the design of parts subject to perpendicular to its action plan are also subject to axial compression; Improve the design of prestressed slender walls.