{"id":312,"date":"2022-12-29T15:53:53","date_gmt":"2022-12-29T15:53:53","guid":{"rendered":"https:\/\/ergo-fix.com\/?p=312"},"modified":"2023-01-03T09:18:52","modified_gmt":"2023-01-03T09:18:52","slug":"wind","status":"publish","type":"post","link":"https:\/\/ergo-fix.com\/?p=312","title":{"rendered":"wind"},"content":{"rendered":"

Cladding panel design<\/h4>\n

Minimal rainscreen cladding panel thickness for secure fixing with standard methods and systems is obtained after precise calculations for:<\/p>\n

1. Wind loads and self-weight
\nWhen considering an external multi-layer wall such as a ventilated fa\u00e7ade, wind loads present a complex load pattern. They are a key factor for safe, practical and economically viable design. We will discuss wind load analysis, design and best practices in an upcoming article.<\/p>\n

2. Type of material used
\nDepending on the material of the rainscreen cladding panels, fa\u00e7ade engineers calculate the minimum, optimal thickness. All materials have their unique characteristics, especially \u201cnon-man-made\u201d ones. Properties of the materials, as well as geometrical data are some of the key variables that determine structural reliability.<\/p>\n

In this article, we explore four material types \u2013 two natural (granite and limestone) and two \u201cman-made”(ceramic and fibre-cement) for a panel with dimensions 1200mm\/600mm to determinate relative minimal thickness.<\/p>\n

1) Natural, or \u201cnon-man-made” materials – Limestone & Granite
\nStone is strong enough to resist hygrometric differential movement, deflection, vibration and creep of the support concrete structure, altogether with weathering and deterioration of the cladding stones. Stone safety factors can vary widely because of its natural origin and non-homogeneous structure. In time, stone can change its physical properties due to heating \u2013 freezing cycle and saturation. Therefore, stone standards are more conservative – with high factors and assuming the lowest flexural strength values.<\/p>\n

 <\/p>\n

\"Rainscreen

Rainscreen cladding – Granite<\/p><\/div>\n

 <\/p>\n

\"Rainscreen

Rainscreen cladding – Limestone<\/p><\/div>\n

 <\/p>\n

<\/h5>\n

2) Artificial, or \u201cman-made” materials – Ceramic & Fibre-cement<\/h4>\n

\u2018Man-made\u2019 materials consist of natural stone fragments, clay, cement, fibres such as glass and cellulose. Additional chemicals and water serve to achieve a more consistent mixture. During the heating or drying process, they transform into microscopic bubbles which are visible in the end product. Due to the controlled nature of the manufacturing process, the safety factor is more predictable and substantially lowered.<\/p>\n

\"Rainscreen

Rainscreen cladding – Fibre Ciment<\/p><\/div>\n

 <\/p>\n

\"Rainscreen

Rainscreen cladding – Ceramic<\/p><\/div>\n

Fibre-cement<\/h5>\n

Fibre cement is a modern reinforced material. The base mixture can be of cement, sand, cellulose and water (autoclave) or cement, lime, synthetic fibres and water (air-cured). The mixture is rotated in different cylinders, vacuum processed, pressed to obtain density, as well as the required thickness and, lastly, air-cured or autoclave cured.<\/p>\n

 <\/p>\n

3. Stresses according to applicable standards<\/h4>\n

This case study will consider the combination of panel self-weight and wind loads applied on the corner fa\u00e7ade segment for a building 40 m high in an urban area. Initially, we\u2019ll also look at an optional computational concept for rainscreen cladding panel design.<\/p>\n

1) Bending moment due to wind load on rainscreen cladding panel<\/h5>\n

Considering the characteristic wind pressure, the design bending moment per unit of width in the panel\u2019s mid-span cross-section is given by:<\/p>\n

\"\"<\/p>\n

    \n
  • Span length: l (m)<\/li>\n
  • Characteristic wind pressure: w (kN\/m2)<\/li>\n
  • Partial safety factor for variable actions: \u03b3_f = 1,5 (according to Eurocode)<\/li>\n<\/ul>\n

    Note: A computer program for static analysis can calculate the bending moment more accurately.<\/p>\n

    2) Bending strength of cladding panel<\/h5>\n

    Characteristic bending strength \u201e \u03c3Rk\u201d<\/strong><\/p>\n

    Usually, the expected lower value of material property or product is unfavourable, and the 5% (lower) fractile is then considered as the characteristic value.<\/p>\n

    Design bending strength \u201e \u03c3Rd\u201d<\/strong><\/p>\n

    \"\"<\/p>\n

    Partial safety factor for material: \u03b3_m\u2248 2 (according to DIN 18516 – 3)<\/p>\n

    3) Thickness of the rainscreen cladding panel<\/h5>\n
    \"\"
    \n4) Example calculation of rainscreen cladding panel thicknesses for different types of materials<\/h5>\n

    Cladding panel dimension properties<\/p>\n

    \u25ba Cladding panel length: a = 1,2 m
    \n\u25ba Cladding panel width: b = 0,6 m<\/p>\n

     <\/p>\n

    Wind load<\/strong><\/p>\n

    Project location: Berlin, Germany (according to Eurocode \u2192 terrain IV)<\/p>\n

    Building height: 50 m<\/p>\n

    \u25ba Characteristic wind pressure for corner areas: w = 1,30 kN\/m2<\/p>\n

    Static scheme of rainscreen cladding panel<\/strong><\/p>\n

    \"\"<\/p>\n

     <\/p>\n

    Support restraints<\/span><\/p>\n

    \u25ba Support 1 \u2013 simply supported (Ux = 0; Uy = 0; Uz = 0)<\/p>\n

    \u25ba Support 2 \u2013 simply supported (Uy = 0; Uz = 0)<\/p>\n

    \u25ba Support 3 \u2013 simply supported (Uz = 0)<\/p>\n

    \u25ba Support 4 \u2013 simply supported (Uz = 0)<\/p>\n

     <\/p>\n

    Bending moment<\/strong><\/p>\n

    \"\"<\/p>\n

    Rainscreen cladding – M = 0,307 kN.m\/m<\/p>\n

    Rainscreen cladding panel thickness for different types of materials<\/p>\n

    The rainscreen cladding panel thicknesses shown in the table below are calculated by the derived formula (as explored above):<\/p>\n\n\n\n\n\n\n\n
    Material<\/strong><\/td>\nHardness<\/strong><\/td>\nBending moment M(<\/strong>kN.m\/m<\/strong>)<\/strong><\/td>\nAverage Bending strength (MPA)<\/strong><\/td>\nDesign Bending strength <\/strong>\u03c3Rd<\/sub><\/strong>(<\/strong>MPa<\/strong>)<\/strong><\/td>\nPanel thickness (cm)<\/strong><\/td>\n<\/tr>\n
    Limestone<\/td>\nMedium hard<\/td>\n0,307<\/td>\n2\u00f721<\/td>\n3,8<\/td>\n2,2<\/td>\n<\/tr>\n
    Granite<\/td>\nHard, durable<\/td>\n0,307<\/td>\n3\u00f730<\/td>\n4,6<\/td>\n2,0<\/td>\n<\/tr>\n
    Ceramic<\/td>\nVery hard<\/td>\n0,307<\/td>\nVast range<\/td>\n50<\/td>\n0,6<\/td>\n<\/tr>\n
    Fibre-cement<\/td>\nHard, stable<\/td>\n0,307<\/td>\n22\u00f732<\/td>\n26<\/td>\n0,8<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

     <\/p>\n

    The illustrations below demonstrate the stress distribution on rainscreen cladding panels made of the four materials with the resulting optimal thicknesses (as explored above).<\/p>\n

    \"\"<\/p>\n

     <\/p>\n","protected":false},"excerpt":{"rendered":"

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