scholarly journals Force reduction factors for the seismic provisions of the National Building Code of Canada

1987 ◽  
Vol 14 (4) ◽  
pp. 447-454 ◽  
Author(s):  
J. H. Rainer
Keyword(s):  
Building Code ◽  
Load Factor ◽  
Limit States ◽  
Load Factors ◽  
Earthquake Resistant Structures ◽  
Structural Configurations ◽  
Force Reduction ◽  
Factor Α ◽  
Reduction Factors

A derivation of force reduction factors for the seismic provisions of the National Building Code of Canada (NBCC), 1985, is presented. This includes the following: classification of seismic actions, applicable limit states, change in load factor, derivation of force reduction factors, and classification of structural configurations. Quantitative comparisons are made between the derived force reduction factors and the response modification factors of the Applied Technology Council and good agreement was found. It is suggested that seismic requirements should be considered as accidental actions with a load factor αQ = 1.0. These results can form the basis for possible modifications to the 1985 NBCC seismic provisions. Key words: earthquake resistant structures, building code, loads, load factors.

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.

Comparison of Recent Parametric Trenched and Partially Embedded/ Spanning Pipelines With DNV-RP-F109 Load Reduction Design Curves

2012 ◽  
Author(s):  
Terry Griffiths ◽  
Wenwen Shen ◽  
Mengmeng Xu ◽  
Jeremy Leggoe
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Reduction Factor ◽  
Load Factor ◽  
Load Reduction ◽  
Load Factors ◽  
Time Histories ◽  
Force Time ◽  
Cfd Analyses ◽  
Reduction Factors

An extensive series of 2D CFD analyses of subsea pipelines with parametrically varying seabed profiles have been performed in the past two years. These cases feature variations on wave and current flow conditions with pipeline partial embedment or spanning which extend beyond the range of conditions which have been published to date. This paper presents a comparison of the reduction factors calculated from this work with DNV-RP-F109 load factors and previous published research. At present, the DNV-RP-F109 partial embedment / trenched pipeline load reduction factors are applied in both absolute stability analysis and also as a reduction factor on hydrodynamic force-time histories used in dynamic stability analysis. The suitability of this load factor reduction for dynamic stability analysis will also be considered. In addition, a limited number of cases have been constructed in 3D which provide some initial insights into the variation of hydrodynamic loads across a pipeline span as a function of finite span length, enabling the validity of applying the 2D DNV load reduction factors across a 3D span to be considered. The 3D cases also consider inclined attack angles, and the effect they have on hydrodynamic forces across a span.

Safety and limit states design for reinforced concrete

1976 ◽  
Vol 3 (4) ◽  
pp. 484-513 ◽  
Author(s):  
J. G. MacGregor
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
American Concrete Institute ◽  
Building Code ◽  
Structural Safety ◽  
Reinforced Concrete Structures ◽  
Limit States ◽  
Load Factors ◽  
New Formula ◽  
State Of Art

This state-of-art paper reviews the concept of limit states design. Following a brief review of statistical definitions the sources of variability in reinforced concrete structures are reviewed. Methods of defining structural safety are reviewed. Following a derivation of the procedures used to compute load and [Formula: see text] factors, a series of [Formula: see text] factors compatible with the 1975 National Building Code of Canada load factors are computed. With the exception of the value for shear the new [Formula: see text] factors are lower than the current American Concrete Institute and Canadian Standards Association values by about the amount of the ratio of load factors in National Building Code of Canada and American Concrete Institute. The computed [Formula: see text] for shear is considerably lower than the corresponding value from the American Concrete Institute Code. An Appendix traces the development of the American Concrete Institute load and [Formula: see text] factors.

Development of loading-truck model and live-load factor for the Canadian Standards Association CSA-S6 code

1987 ◽  
Vol 14 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Akhilesh C. Agarwal ◽  
Moe S. Cheung
Keyword(s):  
Highway Bridges ◽  
Load Level ◽  
Load Factor ◽  
Live Load ◽  
Limit States ◽  
Load Factors ◽  
Loading System ◽  
Using Data ◽  
Council Of Ministers ◽  
Level Loading

Studies have shown that the MS-200 loading model in the Canadian Standards Association standard CAN3-S6-M78 for design of highway bridges no longer represents modern-day heavy trucks in Canada. For the new edition of the CSA-S6 code, based on the limit states philosophy, a new loading-truck model was developed based on the Council of Ministers' loading, which is the legal load limit for interprovincial transportation in Canada. The loading model, designated as the "CS-W loading truck," provides the flexibility to adopt a multiple-level loading system appropriate to various jurisdictions.The live-load factor was determined from a statistical approach using data from a truck survey conducted across Canada in seven provinces. Responses in simple-span bridges were determined by running one or more trucks from the survey across the bridge. Based on this study, a live-load factor of 1.60 was determined and CS-600, with a gross weight of 600 kN, was selected as the standard load level. As well, the validity of the truck model and the live-load factors were checked for continuous-span bridges. Key words: highway bridges, design loads, codes and standards, live-load models, load factors, load surveys, vehicle weight regulations.

Limit states design of concrete slender columns

1987 ◽  
Vol 14 (4) ◽  
pp. 439-446 ◽  
Author(s):  
S. A. Mirza ◽  
J. G. MacGregor
Keyword(s):  
Structural Design ◽  
Current Knowledge ◽  
Building Code ◽  
Limit States ◽  
Resistance Factors ◽  
Development Of Resistance ◽  
Load Factors ◽  
Building Load ◽  
The Moment ◽  
Slender Columns

The limit states design requires the use of load factors and resistance factors to consider the probability of overloading, understrength, or both. Research has been underway in Canada to introduce the probability-based limit states design for concrete structures. Based on the current knowledge of building load statistics, the National Building Code of Canada adopted a set of load factors which are different from those used in the Canadian Standards Association Standard A23.3-M77. This required the development of resistance factors that would be compatible with the load factors specified in the National Building Code of Canada. The research reported herein discusses the development of such resistance factors for use in computing the moment magnification of concrete slender columns. Key words: building codes, load factors, loads (forces), moment magnification, reinforced concrete, resistance, resistance factors, slender columns, stability, structural design.

scholarly journals An Efficient Approach to Obtain Optimal Load Factors for Structural Design

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Juan Bojórquez ◽  
Sonia E. Ruiz
Keyword(s):  
Reinforced Concrete ◽  
Mexico City ◽  
Structural Reliability ◽  
Building Code ◽  
Load Factor ◽  
Optimization Approach ◽  
Load Combination ◽  
Load Factors ◽  
Optimal Load ◽  
Concrete Elements

An efficient optimization approach is described to calibrate load factors used for designing of structures. The load factors are calibrated so that the structural reliability index is as close as possible to a target reliability value. The optimization procedure is applied to find optimal load factors for designing of structures in accordance with the new version of the Mexico City Building Code (RCDF). For this aim, the combination of factors corresponding to dead load plus live load is considered. The optimal combination is based on a parametric numerical analysis of several reinforced concrete elements, which are designed using different load factor values. The Monte Carlo simulation technique is used. The formulation is applied to different failure modes: flexure, shear, torsion, and compression plus bending of short and slender reinforced concrete elements. Finally, the structural reliability corresponding to the optimal load combination proposed here is compared with that corresponding to the load combination recommended by the current Mexico City Building Code.

Effect of guy initial tension on design of guyed antenna towers

1996 ◽  
Vol 23 (2) ◽  
pp. 457-463
Author(s):  
Yohanna M. F. Wahba ◽  
Murty K. S. Madugula ◽  
Gerard R. Monforton
Keyword(s):  
Load Factor ◽  
Case Scenario ◽  
Limit States ◽  
Initial Tension ◽  
Worst Case ◽  
Design Procedures ◽  
Design Engineers ◽  
Load Factors ◽  
Current Design ◽  
Guyed Towers

This study examines the effect of changing the initial guy tension on the design of guyed antenna towers. Six different guyed towers with various heights and loading conditions are used in this study, in which initial guy tensions are changed and the corresponding effect on the forces in the tower components are examined. Also, the methods used in measuring the initial tension are reviewed. On the basis of this study, it is proposed that the initial guy tensions have a load factor different from the value of 1.0 suggested in CSA S37-94. Two additional load combinations are developed from this analysis in order to assist design engineers in determining the worst case scenario for the variation of initial tension in the guys. Results are compared for designs using the current design procedures and the design using the proposed load factors for initial tensions in guy wires. Key words: antenna towers, guyed towers, limit states design, guys, initial tension.

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