scholarly journals Combination of Permanent and Variable Load Is Dependent

2021 ◽  
Vol 11 (10) ◽  
pp. 4434
Author(s):  
Tuomo Poutanen ◽  
Sampsa Pursiainen ◽  
Tim Länsivaara
Keyword(s):  
Structural Design ◽  
Physical Structure ◽  
Variable Load ◽  
Random Load ◽  
Design Work ◽  
Design Load ◽  
Load Combination ◽  
New Findings ◽  
Multiple Structures ◽  
Multiple Load

This study concerns the combination of the permanent and the variable loads in the structural design. The Eurocodes are used as a reference. Three new findings are presented: (1) In each physical structure, and in every load pair of the permanent load and the variable load, the maximum variable load is the service time load, the 50-year load, i.e., the high value of the variable load. Therefore, no load reduction should be applied in the combination. (2) The governing hypothesis is the independent load combination (ILC) with random load pairs and random single loads. However, the load pairs are not independent as normally one variable load occurs simultaneously in multiple structures and in multiple load pairs inducing correlation between the loads, ultimately full correlation, and the dependent load combination (DLC). (3) In the current Eurocodes, the design load combination applies to one load pair only. However, one design load combination virtually always applies to multiple load pairs which demands using the DLC. The authors have explained earlier that the permanent and variable loads should be combined dependently as the ILC contradicts the physics. The new findings support this conclusion. Changing the current codes towards the DLC approach would simplify them and eases their use in the structural design work.

scholarly journals Calculation of Safety Factors of the Eurocodes

2020 ◽  
Vol 11 (1) ◽  
pp. 208
Author(s):  
Tuomo Poutanen ◽  
Tim Länsivaara ◽  
Sampsa Pursiainen ◽  
Jari Mäkinen ◽  
Olli Asp
Keyword(s):  
Safety Factor ◽  
Simple Algorithm ◽  
Convolution Equation ◽  
Current Approach ◽  
Variable Load ◽  
Safety Factors ◽  
Random Load ◽  
Numerical Accuracy ◽  
Load Combination ◽  
Reliability Calculation

This study concerns the safety factor and the reliability calculation for structural codes. The Eurocodes are used as a reference. Safety factor calculation is a demanding task which necessitates using an appropriate root-solving algorithm with a sufficient numerical accuracy. This article introduces a simple algorithm to calculate the safety factors directly, as previously there has been no means to control the accuracy. Presently, the safety factors are defined indirectly through the reliability index. The basic safety factor calculation is presented here in six different equations with the same outcome but differences regarding the numerical calculation, which provides a method to check the accuracy and select a proper equation for the root solver. The safety factor calculation for the permanent and the variable load in the Eurocodes is based on the independent, i.e., random, load combination and single load pairs. The current approach of safety factor calculation applied in the Eurocodes is disclosed here. Simple analytical equations based on the convolution equation are presented. Those can be used instead of the computer programs applied currently.

Design on Four DOF Pneumatic Conveyance Manipulator Based on PLC

2013 ◽  
Vol 319 ◽  
pp. 616-621
Author(s):  
Xiao Mei Wang ◽  
Xiong Zhou ◽  
Meng Tao Yang
Keyword(s):  
Circuit Design ◽  
Structural Design ◽  
Degrees Of Freedom ◽  
Low Cost ◽  
Design Work ◽  
Work Task ◽  
Pneumatic Control ◽  
Plc Control ◽  
Work Cycle ◽  
Pneumatic Conveyance

The design of four degrees of freedom pneumatic conveyance manipulator based on PLC is introduced in the paper. The work task of the manipulator was briefly introduced. The structural design, work cycle, pneumatic control circuit design and PLC control system design are introduced in detail. The manipulator has the advantages of simple in design, stable and reliable act,research and development in low-cost. The design is to provide a reference for other design of economic type manipulators.

LeMill

2011 ◽  
pp. 147-167
Author(s):  
Tarmo Toikkanen ◽  
Jukka Purma ◽  
Teemu Leinonen
Keyword(s):  
Teacher Training ◽  
Open Source ◽  
Design Methods ◽  
Learning Object ◽  
Behavioral Patterns ◽  
Design Work ◽  
Iterative Design ◽  
Open Source Project ◽  
New Findings ◽  
Learning Object Repositories

LeMill is an open source OER repository where the emphasis has been placed on designing a service to meet the actual needs of teachers preparing for classes. The development of LeMill has utilized open, collaborative, and iterative design methods and many features have been refined or redesigned during the process. Emphasis on design work has helped LeMill avoid and fix problems that generally pester OER repositories because of their origins as learning object repositories. The authors recognize that LeMill, as an open source project, has had the rare benefit of a long, structured dissemination phase incorporating actual teacher training. Even when developers and designers try to keep teachers in mind, actual behavioral patterns and needs appear only after the service has been in use. Therefore systems should initially be flexible enough to allow changes resulting from new findings.

Comparative Study on Design of Exposed Penstock Laid on Ground Using Chinese and American Specifications

2014 ◽  
Vol 580-583 ◽  
pp. 2000-2006
Author(s):  
Lei Hu ◽  
He Gao Wu ◽  
Chang Zheng Shi ◽  
Ying Han Xie
Keyword(s):  
Comparative Study ◽  
Wall Thickness ◽  
Structural Design ◽  
Shell Thickness ◽  
Pressure Vessels ◽  
Hydropower Station ◽  
Allowable Stress ◽  
Direct Factor ◽  
Safety Coefficient ◽  
Load Combination

In this paper, differences by using selected three typical specifications—DL/T 5141-2001 (Chinese), ASCE No.79 in the version of 1993(American) and ASCE No.79 in the version of 2012 (American)—in structural design of exposed steel penstock were explored. A practical example about exposed penstock laid on ground applied in hydropower station was also used to analyze specifications clearly. The result shows that the main differences between Chinese and American specifications are allowable stress and load combination. The former is direct factor of calculating exposed penstock shell thickness. Therefore, ASCE No.79 (2012) designs the minimum wall thickness, followed by DL/T 5141-2001 and the last is ASCE No.79 (1993), which is correspondingly contrary to sort by allowable stress. Basically, ASCE No.79 (2012) defines lower safety coefficient for exposed penstock, which is identical with authoritative rules of pressure vessels in the U.S.A and EU. The safety of DL/T 5141-2001 has been proved via rich engineering experience and this specification is recommended for Chinese projects. Besides, ASCE No.79 (2012) is recommended.

Study on Fengdu Second Yangtze River Bridge the Cable Anchorage Structure in a Girder Transfer Mechanism

2011 ◽  
Vol 291-294 ◽  
pp. 2320-2323
Author(s):  
Xie Dong Zhang ◽  
Jin Zhi Wang ◽  
Xiao Dong Wang
Keyword(s):  
Stress Distribution ◽  
Structural Design ◽  
Yangtze River ◽  
Analysis Method ◽  
Analysis Software ◽  
Design Load ◽  
Cable Stayed Bridge ◽  
Plane Analysis ◽  
General Plane ◽  
The Common

The cable anchorage region in a girder is the key part of cable stayed bridge， in which stress distribution is rather complicated. A general plane analysis method is hard to reflect actual stress status. According to the design of Fengdu Second Yangtze River Bridge In this paper, the analysis of the spatial stress distribution of the cable anchorage structure in a girder is carried out in design load by making use of the common analysis software-Midas FEA and spatial finite element method, the verification and assessment of Fengdu Second Yangtze River Bridge Anchor Plate rational structural design is conducted, in order to put forward optimize the design suggestions, to ensure that such structures the realization of economy and reliability.

scholarly journals Biomechanical grounding of the transalveolar osteosynthesis of еdentulous мandible fractures

2021 ◽  
Vol 26 (1) ◽  
pp. 209-217
Author(s):  
N.H. Idashkina ◽  
O.O. Hudarian ◽  
D.V. Chernov ◽  
I.A. Samoilenko
Keyword(s):  
Simulation Modeling ◽  
Three Dimensional ◽  
Calculation Model ◽  
Mandibular Fractures ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Element Analysis ◽  
Design Load ◽  
Load Combination ◽  
3D Computer Simulation

The purpose of the work is improvement of the effectiveness of the mandibular fractures treatment in patients with partial or complete adentia by developing and experimentally testing transalveolar osteosynthesis technique. An experimental study was carried out by 3D computer simulation modeling by the final element analysis to assess the efficiency of mandibular fractures fixation at partial or complete adentia using the Ш-shaped plate, which we developed for the transalveolar osteosynthesis method. Calculations of the immobilized fractures for static (own weight) and dynamic (functional) loads were performed according to the author's method, taking into account pronounced resorptive processes in the bone from the beginning of the reparative reaction to assess the rigidity of fragments fixation during the entire period of the fractures healing. Under the conditions of the same three-dimensional model of the mandible, calculations were performed when the fracture was fixed with ordinary linear titanium osseous plates. It is proved that at functional load the new plate provides a compression effect in the fractures region, as evidenced by the negative displacements in the final elements of the mental region according to the results of design load combination 2- 3. The maximum efforts in the screws of the calculation model with a conventional bone plate were 136.955 N, which is almost ten times more than on the model with a Ш-shaped titanium retainer (12.656 N).

Reliability Calibration of a Waves–Icebergs Interaction Load Combination Factor

2004 ◽  
Author(s):  
Ricardo O. Foschi ◽  
Michael Isaacson ◽  
Norman Allyn
Keyword(s):  
Numerical Analysis ◽  
Offshore Structures ◽  
Combined Effects ◽  
Limit States ◽  
Sea State ◽  
Load Effect ◽  
Design Load ◽  
Load Combination ◽  
Wave Parameters ◽  
Design And Construction

The Canadian Standards Association [1] has developed and published a code for the design and construction of fixed offshore structures. One of the limit states relates to the combined effects of waves and iceberg collision loading. The Code uses a load combination factor to determine the design load effect. The present paper describes a recent study on the appropriateness of the recommended value of the combination factor. The study involves a numerical analysis in which loads have been calculated, at different probability levels, for a range of iceberg and wave parameters, considering waves alone, an iceberg alone, and an iceberg and waves in combination. The paper thereby makes recommendations for the load combination factor as a function of iceberg and sea state parameters.

Probabilistic Risk Assessment for FPSO Topside Structures Under Drop Impact: An Application to Pipeline Protections

2011 ◽  
Author(s):  
YeongAe Heo ◽  
ByungWoo Kim ◽  
Jae-Kwang Eom
Keyword(s):  
Structural Design ◽  
Structural Damage ◽  
Hazard Analysis ◽  
Drop Impact ◽  
Structural Failure ◽  
Risk Calculation ◽  
Design Load ◽  
Fire And Explosion ◽  
Offshore Industry ◽  
Probabilistic Risk

In offshore structural design, it is necessary to evaluate probabilistic risk so that the topside structure has sufficient capacity to resist the effects of accidental loads such as drop impact, helicopter impact, vessel collision, fire, and explosion. Most engineers in the offshore industry, however, have difficulties in estimating a reliable risk value because there are still too many uncertainties in computing the probability of exceeding a target structural damage where the guideline for hazard analysis, which provides design load, is quite well described. Therefore, a framework to compute reasonable probability of structural failure is proposed in this paper. 88 impact scenarios were applied to a pipeline protection system on a topside module of Nexus genetic FPSO in order to perform regression analysis for structural damage. For risk calculation, the hazard analysis in this study is based on the detail engineering report worked by Ramboll Oil & Gas.

Structural Weight Estimations for Novel Configurations

1962 ◽  
Vol 66 (613) ◽  
pp. 15-30 ◽  
Author(s):  
M. E. Burt
Keyword(s):  
Statistical Analysis ◽  
Structural Design ◽  
Minimum Weight ◽  
Optimum Structure ◽  
Weight Estimation ◽  
Design Work ◽  
Detailed Design ◽  
The Past ◽  
Load Carrying ◽  
Actual Design

SummaryThe aims of structure weight estimation are discussed and a review is given of its development in this country during the past fifty years from the simplest of formulae to quite detailed methods. The limitations of formulae derived only from statistical analysis of actual aircraft structures are noted. For aircraft of novel configuration it is essential for the weight of the basic load-carrying structure to be estimated by methods which are based upon the actual design and stressing procedures. The principles of “optimum” or “minimum-weight” structural design are a valuable feature of such methods and are briefly described. Statistical analysis, however, is still important for estimating the substantial weight of the joints, cutouts, transparencies and other features which transform a theoretical optimum structure into a complete and practical one. The problems of several aeroplane and missile configurations of current interest are discussed, and also the extent to which detailed design work is necessary to provide reliable structure weight estimates for such projects.

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