Глибина обвуглення вогнезахищених стійок дерев’яних каркасних стін в умовах пожежі
Date
2019-02-26
Journal Title
Journal ISSN
Volume Title
Publisher
Видавництво Львівської політехніки
Abstract
Сучасні нормативні документи не дають вказівок щодо розрахунку дерев’яних
елементів, що захищені покриттям антипіреном та облицюванням шпунтованими
дерев’яними панелями одночасно. Досліджено вплив такого комбінованого вогнезахисту
на глибину обвуглення стійок дерев’яних каркасних стін в умовах пожежі. Для
дослідних зразків використовували дерев’яну обшивку типу “вагонка” та вогнебіозахисні
розчини, що промислово випускаються в Україні. Дослідження проводили на
середньорозмірних моделях у лабораторних умовах за високотемпературного впливу у
вогневій печі на вогнезахищених та незахищених зразках. Під час експерименту
контролювали температурні показники у конструкції стіни та виміряли глибини
обвуглення перерізів після проведення експерименту. В результаті досліджень було
проаналізовано вплив досліджуваного вогнезахисного розчину на глибину обвуглення
стійок в умовах параметричного вогневого навантаження. Було виконано числовий
аналіз відповідно до національних та європейських норм та проведено порівняння із
експериментальними результатами.
The present standards do not consider cases for timber elements covered with fireresistant penetrating coatings and jointed claddings simultaneously. This article is focused on the influence of such combined fire protection on charring depth of studs in timber frame wall assemblies exposed to fire. A key idea was to investigate rather common in local building types of wall assemblies. Wood panels with rabbet joints as cladding with commercially available fire-coating were used for the frame specimens with loose-fill mineral wool filling. The studs were protected also with timber laths which carried the panels forming an air gap between the cladding and insulation material. Two furnace model scale fire tests were performed in the fire test laboratory of LPNU. Temperature analysis was conducted at control points inside wall assemblies. The calculations according to EN 1995-1-2 are introduced to compare with experimental results. Studies show the impact of investigated coating on the charring rate for studs (150×50 mm), but not for 12 mm wood cladding. Also, using loose-fill mineral wool for insulating tends to char accelerating for the lateral side of studs. The experimental residual cross-section shape considers a faster recession of the wide side surface due to heat transfer through the insulation. Otherwise, timber laths reduce charring of bottom surface exposed to fire. Therefore, residual cross-section shape is different than the predictable traditional form respectively EN. Despite that, this conservative design approach covered experimental data for residual cross-section of unprotected studs. For fire-coating protected studs, experimental results charring depth is smaller against traditional calculations. That reveals the necessity of further improving computational methods. Wood cladding with rabbet joints fell off almost at the same time (unprotected and protected as well). Possible reasons could be insufficient fire-resistant coatings penetrating in the joint area (covering was performed in-situ), air gaps between wood panels due to the geometry tolerance, air gap between the cladding and insulation material (increasing heat transfer after local fall-off), etc. These issues need to be investigated additionally.
The present standards do not consider cases for timber elements covered with fireresistant penetrating coatings and jointed claddings simultaneously. This article is focused on the influence of such combined fire protection on charring depth of studs in timber frame wall assemblies exposed to fire. A key idea was to investigate rather common in local building types of wall assemblies. Wood panels with rabbet joints as cladding with commercially available fire-coating were used for the frame specimens with loose-fill mineral wool filling. The studs were protected also with timber laths which carried the panels forming an air gap between the cladding and insulation material. Two furnace model scale fire tests were performed in the fire test laboratory of LPNU. Temperature analysis was conducted at control points inside wall assemblies. The calculations according to EN 1995-1-2 are introduced to compare with experimental results. Studies show the impact of investigated coating on the charring rate for studs (150×50 mm), but not for 12 mm wood cladding. Also, using loose-fill mineral wool for insulating tends to char accelerating for the lateral side of studs. The experimental residual cross-section shape considers a faster recession of the wide side surface due to heat transfer through the insulation. Otherwise, timber laths reduce charring of bottom surface exposed to fire. Therefore, residual cross-section shape is different than the predictable traditional form respectively EN. Despite that, this conservative design approach covered experimental data for residual cross-section of unprotected studs. For fire-coating protected studs, experimental results charring depth is smaller against traditional calculations. That reveals the necessity of further improving computational methods. Wood cladding with rabbet joints fell off almost at the same time (unprotected and protected as well). Possible reasons could be insufficient fire-resistant coatings penetrating in the joint area (covering was performed in-situ), air gaps between wood panels due to the geometry tolerance, air gap between the cladding and insulation material (increasing heat transfer after local fall-off), etc. These issues need to be investigated additionally.
Description
Keywords
глибина обвуглення, антипірени, стінові конструкції каркасних дерев’яних будинків, пожежа, шпунтовані дерев’яні панелі “вагонка”, стійки, charring depth, fire coating, timber frame wall assemblies, fire, wood panels with rabbet joints, timber studs
Citation
Була С. С. Глибина обвуглення вогнезахищених стійок дерев’яних каркасних стін в умовах пожежі / С. С. Була, Т. М. Шналь // Вісник Національного університету “Львівська політехніка”. Серія: Теорія і практика будівництва. — Львів : Видавництво Львівської політехніки, 2019. — № 912. — С. 3–11.