Behavior of clay hollow-brick masonry walls during fire. Part 1: Experimental analysis

Understanding the behavior of masonry structures when exposed to fire and predicting their fire-resistance is a major need that has been expressed by brick manufacturers. Whereas clay brick masonry is widely used because of its thermal and sound insulation performance; fire-resistance is certainly its weakness if improper design methods are used. These design methods require prior exhaustive experimental tests, which should not be limited to evaluating standard fire-resistance as a global standard criterion but should also permit a detailed analysis of the thermo-mechanical behavior of masonry walls. In this paper, four wall-tests are presented to illustrate the behavior of clay masonry walls during fire. Selected wall-tests are generically representative of the overall results obtained during a more extended experimental campaign. The experimental results are presented and analyzed with regard to the risk of spalling on the fire-resistance of masonry. The analysis contains a detailed investigation of temperature, deformation and local mechanical degradation phenomena in the tested walls. Finally, the study is concluded by summarizing end-point parameters that significantly control the fire-resistance of clay masonry walls and deserve consideration in any modeling approach. ► Detailed thermo-mechanical investigation is carried out. ► Fire-resistance of thin non-bearing walls is controlled by insulation. ► Load-bearing walls lose stability due to localized spalling. ► Only mechanical degradation at some critical locations seems to be driving spalling.