BUILDING PHYSICS 35 For the protection period tch, the time until the burn-off starts behind the gypsum board planking, the values specified under β0 can be measured, when Rigips RF fire protection boards, Rigidur H gypsum fibre boards or Riduro wooden building slabs are used. Burn-off rate β0 Component description Burn-off rate β0 [mm/min] Wall, 3 or 5 or more than 5 layers, initially protected or unprotected, 30 to 90 min. fire duration 0.75 Ceiling, 3 or 5 or more than 5 layers, initially protected or unprotected, 30 to 90 min. fire duration 0.90 The measuring rules explained in this Section have been confirmed in an official expert report by an accredited testing institution. Burn-off behaviour of CLT BBS components protected by gypsum boards The time when the planking fails, tf, as well as the time when the burnoff of the CLT BBS elements starts behind the protecting planking, tch, are required in order to calculate the burn-off of a structure without the good test results of the company binderholz purely on the basis of the Euro standard EN 1995-1-2 requires. From the time tch, the carbonisation of the CLT BBS begins at a reduced burn-off speed. After this fire phase, the time tf occurs, from which the planking fails by falling off. From this moment in time, the CLT BBS begins to burn off, according to the Eurocode model, at an accelerated speed of 1.30 mm/min. Saint-Gobain Rigips Austria had its products used for fire protection • Rigips RF fire protection board, • Rigidur H gypsum fibre board, • and Riduro wooden building slab evaluated regarding tch and tf on the basis of numerous fire tests. The table shows a summary of the results. Calculation table for the burn-off rate of protected components Wall components Hardwood with direct planking Facing formwork in solid timber construction t 100 2.8 * d – 22.7 2.8 * d – 22.7 t ch 2.8 * d – 14 2.8 * d – 14 t f 2.2 * d + 4 1.73 * d + 30.7 Ceiling components Hardwood with direct planking Suspended ceiling in solid timber construction t 100 2.8 * d – 22.7 2.8 * d – 22.7 t ch 2.8 * d – 14 2.8 * d – 14 t f 2.2 * d + 4 2.43 * d + 0.22 d: Plate thickness of the outer layer in mm and 80% of the thickness of the inner layers if multi-layered t100: Time of overtemperature of 100 K behind the planking tch: Beginning of the burn-off behind the planking in minutes tf: Time of failure behind the planking in minutes Advantages from the binderholz tests on the burn-off behaviour of binderholz CLT BBS The protective effect of the gypsum boards can be assessed up to the time tch for initially protected components. Thereafter, the residual cross section of the binderholz CLT BBS is to be calculated by means of the average burn-off rate explained under the calculation table. This calculation method results in residual cross sections that come closer to the tested values than the conservative model of the Eurocode EN 1995-1-2. Assessment software The assessment program offered free of charge by binderholz contains the tested burn-off rates of CLT BBS. Likewise, the protection times of initially protected components can be entered here. Thus, it is possible to quickly and effectively render proof for the CLT BBS components in the event of a fire and it can be printed out and filed in a transparent manner. For testable structural analysis proof based on the Euro code 5, we can make a free assessment program available to you (see Figure 20) and which can be requested from bbs@binderholz.com. All relevant characteristic product values are saved in this program. Figure 20 – binderholz DC structural analysis program
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