Masonry Mechanical Properties

Annex D (informative) of prEN1996-1-2 provides the temperature-stress-strain relationships for AAC, calcium silicate and lightweight aggregate concrete units as shown in Figures 1 to 3, respectively. In these figures, the stress has been normalised by the stress at 20°C. The design data shows that the masonry units generally become less brittle at elevated temperatures, with a prolonged strain corresponding to the maximum compressive stress. It is also interesting to notice that, besides lightweight aggregate concrete unit, the AAC and calcium silicate units even achieved higher compressive strength during heating. However, it is noteworthy that the design data provided by the code refers only to the masonry units. It is generally expected that the design strength of masonry constructions is smaller than individual masonry units.

Figure 1 Normalised Temperature-stress-strain Relationships for AAC Units with Unit Strength 4-6 N/mm2 and Density Range of 900-1200 kg/m3 (EN1996-1-2: 2003)	Figure 2 Normalised Temperature-stress-strain Relationships for Calcium Silicate Units with Unit Strength 12-20 N/mm2 and Density Range of 1600-2000 kg/m3 (EN1996-1-2: 2003)

Figure 3 Normalised Temperature-stress-strain Relationships for Lightweight Aggregate Concrete Units with Unit Strength 4-6 N/mm² and Density Range of 600-1000 kg/m³ (EN1996-1-2: 2003)