Dimension stone design – partial safety factors: a reliability based approach

Abstract

Today's thin stone veneers must be designed to resist, besides their self-weight, high wind pressures and induced seismic forces. They must accommodate hygrometric differential movement, deflection, vibration and creep, etc. When available, code requirements do not provide an accurate or realistic safety factor for the specific type of anchor and or stone used in a project. Global safety factors that are recommended by stone industry associations are imprecise and used as rules of thumb. Limit state design has replaced the older concept of allowable stress design in most forms of civil engineering. As a result, all modern buildings are designed in accordance with a code which is based on limit state theory for all man-made materials, yet there is an astonishing nonexistence of ′natural stone′. In this paper partial factors of safety are proposed depending on the types and on the coefficients of variation of the distributions of resistances. Their values are determined using structural reliability analysis for the load and resistance factor design format according to Eurocode 1990. Aging and stone resistance decay is outside the scope of the article, yet some guidance is provided on the influence of stone durability on stone cladding performance. An application example is used to illustrate both methods, and conclusions are drawn.

Editorial

“…Returning to stone cladding applications, there are two thoughtful papers by Rui S. Camposinhos (2012) and Rui S. Camposinhos and Rui Pedro A. Camposinhos (2012). In the first paper, the author is concerned at the common use of imprecise 'rules of thumb' and 'global safety factors', which he feels are often 'archaic' and less applicable for modern thin cladding systems.…”

Durability of Stone Cladding in Buildings: A Case Study of Marble Slabs Affected by Bowing

“…Empirical design formulas based on geometrical/mechanical characteristics of the stone slabs and fixing/anchorage systems are available [18,23]. Moreover, the evaluation of the wind stability/safety assessment methodology is also defined for stone cladding using serviceability/ultimate limit sates methodology and partial safety factors, which are defined according to the coefficient of variation of stone properties [18,24,25]. In addition, the design of stone slabs should also include numerical simulations in order to evaluate the stress levels induced by the wind action/pressure.…”

Effect of Freeze-Thaw Cycle on Anchor Fracture Load in Carbonate Rocks

“…Gürcan (2014) investigated the breaking loads of marble, limestone and granite samples of different thicknesses to be used in facade cladding. The study by Pires et al (2011) examined the relationship between bending strength and anchorage system when using cladding materials (slate) with anisotropic plane in exterior cladding applications, as well as the importance of the bending behaviors of materials used for exterior cladding exposed to wind and physical impacts (Camposinhos and Camposinhos 2009;Moreiras et al, 2008;Camposinhos 2012). explored the change in bending behaviors of buildings clad with natural stone in relation to changes in humidity and temperature and grain sizes.…”