Earthing shock safety design standards

A Simplified Method for Establishing Safe Available Evacuation Time Based on a Descending Smoke Layer

Communications - Scientific letters of the University of Zilina ◽

10.26552/com.c.2018.2.28-34 ◽

2018 ◽

Vol 20 (2) ◽

pp. 28-34

Author(s):

Jiri Pokorny ◽

Vladimir Mozer ◽

Lenka Malerova ◽

Dagmar Dlouha ◽

Peter Wilkinson

Keyword(s):

Fire Safety ◽

Air Entrainment ◽

New Method ◽

Fire Growth ◽

Design Standards ◽

Evacuation Time ◽

Wide Range ◽

Safety Design ◽

Smoke Layer ◽

Fire Safety Design

Keeping the smoke layer at a safe height is one of the most important tenability criteria in assessment of evacuation from buildings. The basis of this approach is an accurate approximation of the fire and smoke plume, which is formed above the fire source. The major variables affecting smoke filling are the fire growth rate and enclosure geometry, i.e. the floor area and height. This paper deals with the implementation of a new method for establishing safe available evacuation time based on the fundamental principles of smoke generation and flow into the national fire safety design standards in the Czech and Slovak Republic. Some of these calculation methods have also been included in fire safety engineering ISO standards. The devised method is based on the t-squared fire growth model and correlations for smoke production and air entrainment into the rising plume of smoke. Subsequently, the proposed method is validated against a wide range of benchmark scenarios in the two-zone fire model CFAST. The paper compares the differences, comments on their causes and evaluates the applicability of the new method in both countries. The proposed method is not only compatible with the national fire safety design standards, but also allows for a more precise assessment of life safety without the need for overly complicated calculations.

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Ultimate strength of fillet welded connections loaded in plane

Canadian Journal of Civil Engineering ◽

10.1139/l90-008 ◽

1990 ◽

Vol 17 (1) ◽

pp. 55-67 ◽

Cited By ~ 41

Author(s):

Dale F. Lesik ◽

D. J. Laurie Kennedy

Keyword(s):

Ultimate Strength ◽

Statistical Data ◽

Fillet Welds ◽

Test Results ◽

Full Scale Test ◽

Design Standards ◽

Limit States ◽

Safety Design ◽

Current Design ◽

Scale Test

Fillet welded connections are frequently loaded eccentrically in shear with the externally applied load in the same plane as the weld group. While some current design tables are based on ultimate strengths, methods of analysis that incorrectly mix inelastic and elastic approaches are still used. These methods give conservative and variable margins of safety. Design standards generally use a lower-bound approach basing strengths on the longitudinal value neglecting, conservatively, the increase in strength for other directions of loading. The factored resistance of fillet welds, as a function of the direction of loading, is established based on ultimate strength expressions developed herein and using geometric, material variations, and test-to-predicted ratios reported in the literature. Factored resistances of eccentrically loaded fillet weld groups are established. These are basesd on the method of instantaneous centres, ultimate strengths, and the load–deformation expressions developed herein that are functions of the angle of loading. Also, statistical data on geometry, material variations, and the comparison of predicted strengths with the full-scale test results of others are used. Tables of design coefficients giving factored resistances for various eccentrically loaded fillet welded connections are developed. The coefficients, on the average, are essentially the same as those in current design tables. Key words: connections, design tables, eccentric, fillet welds, limit states, ultimate strength.

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