Roof snow loads in Canada

1980 ◽  
Vol 7 (1) ◽  
pp. 1-18 ◽  
Author(s):  
D. A. Taylor
Keyword(s):  
Building Code ◽  
Detailed Design ◽  
Design Information ◽  
Snow Loads

The National Building Code of Canada requires buildings to be designed to carry uniformly and nonuniformly distributed snow loads and the "Commentary on Snow Loads" in Supplement No. 4 to the National Building Code of Canada gives detailed design information. This paper discusses the material given in the 1977 commentary and supplements it with examples and photographs.

scholarly journals Unbalanced snow distributions for the design of arch-shaped roofs in Canada

1980 ◽  
Vol 7 (4) ◽  
pp. 651-656 ◽  
Author(s):  
D. A. Taylor ◽  
W. R. Schriever
Keyword(s):  
Building Code ◽  
Large Radius ◽  
Design Loads ◽  
Snow Loads

This note examines in some detail the design snow loads on simple arches and curved roofs recommended in the 1977 Commentary on Snow Loads of the National Building Code of Canada. Empirical modifications that give more appropriate unbalanced snow loads for large-radius arches and that will alleviate the problems caused by some overconservative aspects of the 1977 design loads are presented. They have been accepted for inclusion in the 1980 commentary.

scholarly journals Liability In Conducting Tests

1998 ◽  
Vol 15 (2) ◽  
Author(s):  
Roy J. Leonard
Keyword(s):  
Data Sheet ◽  
Building Code ◽  
Materials Testing ◽  
Testing Laboratory ◽  
Raw Data ◽  
Design Information ◽  
Laboratory Results ◽  
Forensic Engineering ◽  
Project File ◽  
Building Project

Instead Of Earning A Small Fee On A Building Project, A Materials Testing Laboratory Can Instead Become Involved In Litigation Which Could Cost It And Its Liability Insurers An Amount Many Times The Fee. But More Than This, There Could Also Be An Infinitely Greater Amount Of Time Spent Defending The Firm Than Was Ever Spent In Performing The Tests. In The Majority Of Cases The Tests Are Performed To Either Supply Design Information Or Monitor Compliance With Project Specifications And/Or Building Code Requirements. However, If Problems Develop And Litigation Begins, Then The Project File Information Becomes Evidence Of What Took Place On The Project. In Some Cases, However, The Laboratory Is Employed After Litigation Has Begun, Or The Probability Of A Lawsuit Is High, And The Testing Is Performed To Provide Evidence. In Any Event, The Results Of These Tests Are Taken As Essential Facts Which Will Be Reviewed By The Attorneys And Their Forensic Engineering Experts. Sometimes The Technicians Or Managers Of The Firm Providing These Field Or Laboratory Results Will Be Deposed, And Every Raw Data Sheet, Report And Log In The File May Be Examined In Great Detail By The Various Parties. If One Error Is Found, It May Be Contended That There May Be Other Errors Which Have Not Been Found Yet. If It Develops That Any Errors Or Suspected Errors Were Made, Then The Laboratory May Become Party To The Lawsuit.

scholarly journals A Safety Analysis Method for Control Software in Coordination with FMEA and FTA

Information ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 79
Author(s):  
Masakazu Takahashi ◽  
Yunarso Anang ◽  
Yoshimichi Watanabe
Keyword(s):  
Development Process ◽  
Safety Analysis ◽  
Control Flow ◽  
Preliminary Design ◽  
Control Software ◽  
Safety Level ◽  
Detailed Design ◽  
Design Information ◽  
Flow Diagrams ◽  
The Impact

In this study, we proposed a method to improve the safety level of control software (CSW) by managing the CSW’s design information and safety analysis results, and combining failure mode and effects analysis (FMEA) and fault tree analysis (FTA). Here, the CSW is developed using structured analysis and design methodology. In the upper stage of the CSW’s development process, as the input of the preliminary design information (data flow diagrams (DFDs) and control flow diagrams (CFDs)), the causes of undesirable events of the CSW are clarified by FMEA, and the countermeasures are reflected in the preliminary design information. In the lower stage of the CSW’s development process, as the inputs of the detailed design information (DFDs and CFDs in the lower level) and programs, the causes of the specific undesirable event are clarified by FTA, and the countermeasures are reflected in the detailed design specifications and programs. The processes are repeated until the impact of undesirable events become the acceptable safety level. By applying the proposed method to the CSW installed into a communication control equipment on the space system, we clarified several undesirable events and adopted adequate countermeasures. Consequently, a safer CSW is developed by applying the proposed method.

Load factor calibration for the proposed 2005 edition of the National Building Code of Canada: Statistics of loads and load effects

2003 ◽  
Vol 30 (2) ◽  
pp. 429-439 ◽  
Author(s):  
F M Bartlett ◽  
H P Hong ◽  
W Zhou
Keyword(s):  
Companion Paper ◽  
Reduction Factor ◽  
Building Code ◽  
Wind Loads ◽  
Load Factor ◽  
Live Load ◽  
Dead Load ◽  
Wind Speeds ◽  
Code Calibration ◽  
Snow Loads

The 2005 edition of the National Building Code of Canada (NBCC) will adopt a companion-action format for load combinations and specify wind and snow loads based on their 50 year return period values. This paper summarizes statistics for dead load, live load due to use and occupancy, snow load, and wind load that have been adopted for calibration, and a companion paper presents the calibration itself. A new survey of typical construction tolerances indicates that statistics for dead load widely adopted for building code calibration are adequate unless the dead load is dominated by thin, cast-in-place concrete toppings. Unique statistics for live load due to use and occupancy are derived that pertain specifically to the live load reduction factor equation used in the NBCC. Statistics for snow and wind loads are normalized using the 50 year values that will be specified in the 2005 NBCC. New statistics are determined for the factors that transform wind speeds and ground snow depths into wind and snow loads on structures.Key words: buildings, code calibration, companion action, dead loads, live loads, load combinations, load factors, reliability, safety, snow loads, wind loads.

scholarly journals Snow loads for the design of cylindrical curved roofs in Canada, 1953–1980

1981 ◽  
Vol 8 (1) ◽  
pp. 63-76 ◽  
Author(s):  
D. A. Taylor
Keyword(s):  
Building Code ◽  
Design Loads ◽  
Snow Loads

Since 1975 recommended design loads on cylindrical curved roofs in the Commentaries on Snow Loads in National Building Code documents have undergone significant changes. This paper presents data and some of the background to the changes, and discusses the problems that have arisen with the recommendations published in the 1977 Commentary. The intent is to make recommended design snow distributions and loads as realistic as possible without undue complication. Further improvements are suggested.

Revised ground snow loads for the 1990 National Building Code of Canada

1989 ◽  
Vol 16 (3) ◽  
pp. 267-278 ◽  
Author(s):  
M. J. Newark ◽  
L. E. Welsh ◽  
R. J. Morris ◽  
W. V. Dnes
Keyword(s):  
Method Of Moments ◽  
Snow Depth ◽  
Extreme Value Distribution ◽  
Building Code ◽  
Snow Pack ◽  
Snow Density ◽  
Snow Load ◽  
The Mean ◽  
Snow Loads ◽  
Made In

The last systematic recalculation of ground snow loads in the Supplement to the National Building Code of Canada was made in 1977 and used data up to 1975. Data from three times as many stations are now available and there is also an additional 10 years of record. Using this expanded data base, ground snow loads have been recalculated for the 1990 Supplement.Several changes in methods have been utilized, the most significant of which is the use of an objective technique to estimate ground snow loads at Code (or other) locations. It explicitly incorporates an assumed dependence of the snow load on topographical elevation, and accounts for the magnitude of errors at snow depth observation sites. Other differences include (a) the use of the method of moments to fit the Gumbel extreme value distribution for the purpose of estimating the 30-year return period snow depth; (b) the use of geographically varying snow pack densities; and (c) using probabilistic rain components of the total snow load and estimating this component by use of a snow pack model.Results show an average national decrease of 6.6% in the 1990 loads compared with those in the 1985 Supplement. A regional exception is in the Northwest Territories where the use of a greater snow density has led to an average increase of about 16% in the loads. A reduction in the standard deviation about the mean load suggests a more spatially consistent set of values for the 1990 Supplement. Key words: snow, loads, building, code.

scholarly journals A survey of snow loads on the roofs of arena-type buildings in Canada

1979 ◽  
Vol 6 (1) ◽  
pp. 85-96 ◽  
Author(s):  
D. A. Taylor
Keyword(s):  
Pilot Study ◽  
Building Code ◽  
Case Histories ◽  
Annual Survey ◽  
Snow Loads ◽  
Unbalanced Loads

The paper presents data on snow loads on three shapes of arena-type structures in Canada: the cylindrical arch, and the gable and Hipel roofs. Since there has never been a regular annual survey of snow on arenas, the data were compiled from a 4 year pilot study of snow on Quonset-type buildings, from case histories, and from newspaper clippings.The data indicate that the maxima of the loads recommended for design in Commentary H on snow loads published in Supplement No. 4 to the National Building Code of Canada 1977 can be exceeded.Further, it appears from the data that three loading cases should be considered in the design of curved roofs: uniformly distributed, unbalanced, and symmetrical loads. It is apparent also that the unbalanced loads recommended for gable roofs may be too conservative.

Load factor calibration for the proposed 2005 edition of the National Building Code of Canada: Companion-action load combinations

2003 ◽  
Vol 30 (2) ◽  
pp. 440-448 ◽  
Author(s):  
F M Bartlett ◽  
H P Hong ◽  
W Zhou
Keyword(s):  
Companion Paper ◽  
Building Code ◽  
Wind Loads ◽  
Load Factor ◽  
Live Load ◽  
Dead Load ◽  
Limit States ◽  
Snow Load ◽  
Load Factors ◽  
Snow Loads

The 2005 edition of the National Building Code of Canada (NBCC) will adopt a companion-action format for load combinations and specify wind and snow loads based on their 50 year return period values. This paper presents the calibration of these factors, based on statistics for dead load, live load due to use and occupancy, snow load, and wind load, which are summarized in a companion paper. A target reliability index of approximately 3 for a design life of 50 years was adopted for consistency with the 1995 NBCC. The load combinations and load factors for strength and stability checks recommended for the 2005 NBCC were based on preliminary values from reliability analysis that were subsequently revised slightly to address major inconsistencies with past practice. The recommended load combinations and factors generally give factored load effects similar to those in the 1995 NBCC, but are up to 10% more severe for the combination of dead load plus snow load and are generally less severe for the combination of dead load, snow load, and live load due to use and occupancy. Load factors less than one are recommended for checking serviceability limit states involving specified snow and wind loads. Importance factors for various classifications of structure are also presented. Revisions to the commentaries of the NBCC are recommended that will provide guidance on dead load allowances for architectural and mechanical superimposed dead loads and cast-in-place cover slabs and toppings.Key words: buildings, code calibration, companion action, dead loads, live loads, load combinations, load factors, reliability, safety, snow loads, wind loads.

Snow loads in the 1985 National Building Code of Canada: Curved roofs

1985 ◽  
Vol 12 (3) ◽  
pp. 427-438 ◽  
Author(s):  
Timothy H. R. Kennedy ◽  
D. J. Laurie Kennedy ◽  
James G. MacGregor ◽  
Donald A. Taylor
Keyword(s):  
Shear Force ◽  
Circular Cross Section ◽  
Bending Moment ◽  
Building Code ◽  
Bending Moments ◽  
Snow Load ◽  
Wide Range ◽  
Loading Case ◽  
Snow Loads ◽  
Load Intensity

In the 1985 edition of the National Building Code of Canada (NBCC) the intensity of the specified snow load at any location on a roof is obtained by multiplying the ground snow load for the building locale by a series of factors. These factors reflect the overall reduction in average snow loads on roofs as compared with that on the ground, the effect of exposure to wind, the effect of roof slope, and the effect of drifting, sliding, creep, and drainage.The four loading cases for the design of curved roofs suggested in the Commentary on snow loads accompanying the 1980 NBCC were examined by determining, for roofs of circular cross section, the variation across the span of load intensity, shear force, and bending moment for a wide range of spans, ground snow loads, and roof edge slopes. The purpose of the examination was to fully describe known inconsistencies arising from these loading cases.A new case for drift loading was developed (case III) that, when used with "full" or "uniform" loading and with the unbalanced loading developed for the 1977 NBCC (case II), eliminates or at least reduces the inconsistencies. With this new loading case and the derivation of a formula to define when to switch from loading case II to the new case III the designer now has to consider only one unbalanced loading condition rather than three as before.A simplified method for establishing specified load intensities, shear forces, and bending moments, suitable at least for preliminary design, is also presented. Key words: bending moments, curved roofs, drifts, load intensity, shear force, snow load factors, wind.

scholarly journals Expected Snow Loads on Structures from Incomplete Hydrological Data

1977 ◽  
Vol 19 (81) ◽  
pp. 185-195 ◽  
Author(s):  
J. Martinec
Keyword(s):  
Snow Cover ◽  
Frequency Analysis ◽  
Building Code ◽  
Return Periods ◽  
Snow Load ◽  
Hydrological Data ◽  
Regional Effects ◽  
Direct Measurements ◽  
Snow Loads

Abstract An assessment of snow loads in Switzerland was required for a revision of the building code. Settling curves of snow are used to compute water equivalents of snow if direct measurements are not available. Based on a frequency analysis, relations between the snow load and the altitude are given for various return periods. Problems of regional effects and of converting the snow-cover data to roof loads are outlined.

Sign in / Sign up

Export Citation Format

Share Document