Design

Design Parameters for Stone, Brick and Terra Cotta Masonry

  1. For many applications and designers, the use of Allowable Stress Design (ASD), is appropriate, and thus the focus of this manual is on that method. It is also known as Working Stress Design (WSD) in parts of North America. The same procedures can be adapted to the Limit State Design (LSD) method or Load Factored Resistance Method  (LFRD) where design consistency is required with other parts of the project.
  2. Bond pull out strength is typically 65PSI (working stress)  on the circumference of the drilled hole. This is based on 4x safety factor based on actual full scale load tests. This may be reduced in very dense, smooth substrates like granite to as low as 30 PSI
  3. Steel is AISI Type 304 stainless with a yield of 29,000 PSI. We use 0.6 as the strength reduction factor for WSD in bending, tension and shear.
  4. Safe bearing strength for shear loads and/or bending stresses from eccentric loads on sound brick masonry is 300 PSI. Bearing area is calculated on one- half the circumference of the hole, not the projection of the hole diameter.
  5. The sum of the interaction formula for combined stresses shall not exceed 1.0
  6. Pull out and bearing strength of the substrate is based on the ACI standard procedure using an appropriate diagonal tensile stress. Pull out strength in terra cotta units is based on a very conservative value and load tests have always proven that failure load is much higher than we calculate.
  7. The anchors system tends to fail in the substrate. The steel anchor body typically does not fail, and the grout element does not fail in crushing or pull -out if the grout installation has been performed in accordance with Cintec requirements. Therefore design should focus primarily on determining the properties of the substrate.