Finding the optimum layout for cable-stayed bridge in conceptual design

2021 ◽  
Author(s):  
Sami Soppela ◽  
Esko Järvenpää
Keyword(s):  
Longitudinal Direction ◽  
Simple Calculation ◽  
Integral Calculus ◽  
Bearing Material ◽  
Load Bearing ◽  
Permanent Load ◽  
Early Design Stages ◽  
Cable Forces ◽  
The Cost ◽  
Cable Stayed Bridges

<p>In the cable-stayed bridges the primary cost components of the load-bearing material, in the longitudinal direction of the bridge, are the cables. The longer the bridge, the higher the share of the costs of the load-bearing material. The quantity of the cables and the cost optimized cable and tower topology can be reliably solved, already in very early design stages, using a simple calculation method proposed in this article. The cables are considered as a curtain structure and the cable forces are calculated for the permanent load balance. The solutions are performed mathematically by using integral calculus based on a force length method and a unit bridge concept. The results provide a good idea of the optimum pylon height for both one-pylon and two-pylon bridges. The optimum pylon height depends on the span ratio and the chosen cable system.</p>

Conceptual Design of balanced Cable-Stayed Bridges

2019 ◽  
Author(s):  
Sami Soppela ◽  
Esko Järvenpää
Keyword(s):  
Longitudinal Direction ◽  
Design Stage ◽  
Span Length ◽  
Early Design Stage ◽  
Cable Stayed Bridge ◽  
Permanent Load ◽  
Live Loads ◽  
Cable Forces ◽  
Optimum Solution ◽  
Cable Stayed Bridges

<p>The cables are the major loadbearing cost components in the longitudinal direction of a cable-stayed bridge. The quantity of the cables reflects directly to the comparative costs of different alternative layouts. The cable forces, calculated for permanent load balance lead to a reliable cable quantity estimation. For a long-term durability it is important that the bridge is in balance for permanent loads. The influence of the live loads can be estimated separately.</p><p>The purpose of this article is to estimate cable quantities in an early design stage when finding the optimum solution for the bridge. A simple solution method is carried out mathematically using vector algebra and the force length method. This article sets a clear path for determining the preliminary cable forces and cable quantities for two-pylon and single-pylon cable-stayed bridges. The variables are the span length relation, pylon height relation to the main span length, optimum cable anchorage distance at the pylon and the permanent load of the deck.</p><p>Also, the cable quantities of single-pylon bridges can be calculated, even for bridges with highly asymmetric spans. It is noted that the single-pylon cable-stayed bridge has remarkably bigger cable quantity than the two- pylon bridge with equal length.</p><p>The results reveal that the optimum cable anchorage distance in the pylon depends on the pylon height. The higher the pylon is, the greater the optimum anchorage distance should be.</p><p>For the durable bridge an optimum layout and a good balance for gravity loads with minimized bending moments are an important design target. The article helps in reaching that target.</p>

A prediction method for cable forces of cable-stayed bridges using fuzzy processing and Bayes estimation

2021 ◽  
Author(s):  
Li Dong ◽  
Bin Xie ◽  
Dongli Sun ◽  
Yizhuo Zhang
Keyword(s):  
Prediction Method ◽  
Practical Method ◽  
Bayes Estimation ◽  
Primary Data ◽  
Force Estimation ◽  
Element Analysis ◽  
Cable Stayed Bridge ◽  
Input Parameters ◽  
Cable Forces ◽  
Cable Stayed Bridges

<p>Cable forces are primary factors influencing the design of a cable-stayed bridge. A fast and practical method for cable force estimation is proposed in this paper. For this purpose, five input parameters representing the main characteristics of a cable-stayed bridge and two output parameters representing the cable forces in two key construction stages are defined. Twenty different representative cable-stayed bridges are selected for further prediction. The cable forces are carefully optimized through finite element analysis. Then, discrete and fuzzy processing is applied in data processing to improve their reliability and practicality. Finally, based on the input parameters of a target bridge, the maximum possible output parameters are calculated by Bayes estimation based on the processed data. The calculation results show that the average prediction error of this method is less than 1% for the twenty bridges themselves, which provide the primary data and less than 3% for an under-construction bridge.</p>

scholarly journals Mechanics of evolutionary digit reduction in fossil horses (Equidae)

2017 ◽  
Vol 284 (1861) ◽  
pp. 20171174 ◽  
Author(s):  
Brianna K. McHorse ◽  
Andrew A. Biewener ◽  
Stephanie E. Pierce
Keyword(s):  
Body Mass ◽  
Bone Geometry ◽  
Continuous Measure ◽  
Positive Allometry ◽  
Load Bearing ◽  
Beam Analysis ◽  
Body Sizes ◽  
Major Trend ◽  
The Cost

Digit reduction is a major trend that characterizes horse evolution, but its causes and consequences have rarely been quantitatively tested. Using beam analysis on fossilized centre metapodials, we tested how locomotor bone stresses changed with digit reduction and increasing body size across the horse lineage. Internal bone geometry was captured from 13 fossil horse genera that covered the breadth of the equid phylogeny and the spectrum of digit reduction and body sizes, from Hyracotherium to Equus . To account for the load-bearing role of side digits, a novel, continuous measure of digit reduction was also established—toe reduction index (TRI). Our results show that without accounting for side digits, three-toed horses as late as Parahippus would have experienced physiologically untenable bone stresses. Conversely, when side digits are modelled as load-bearing, species at the base of the horse radiation through Equus probably maintained a similar safety factor to fracture stress. We conclude that the centre metapodial compensated for evolutionary digit reduction and body mass increases by becoming more resistant to bending through substantial positive allometry in internal geometry. These results lend support to two historical hypotheses: that increasing body mass selected for a single, robust metapodial rather than several smaller ones; and that, as horse limbs became elongated, the cost of inertia from the side toes outweighed their utility for stabilization or load-bearing.

scholarly journals Structural behaviour and design criteria of under-deck cable-stayed bridges and combined cable-stayed bridges. Part 2: Multispan bridges.

2008 ◽  
Vol 35 (9) ◽  
pp. 951-962 ◽  
Author(s):  
A. M. Ruiz-Teran ◽  
A. C. Aparicio
Keyword(s):  
Prestressed Concrete ◽  
Design Criteria ◽  
Live Load ◽  
Structural Behaviour ◽  
Structural Efficiency ◽  
Stay Cables ◽  
Medium Length ◽  
Permanent Load ◽  
Materials Used ◽  
Cable Stayed Bridges

This paper deals with the application of under-deck cable-staying systems and combined cable-staying systems to prestressed concrete road bridges with multiple spans of medium length. Schemes using under-deck cable-staying systems are not suitable for continuous bridges, as they are not efficient under traffic live load and only allow for the compensation of permanent load. However, combined cable-staying systems are very efficient for continuous bridges and enable the design of very slender decks (1/100th of span) where the amount of materials used is halved in comparison with conventional schemes without stay cables. In this paper, the substantial advantages provided by combined cable-staying systems for continuous bridges (such as high structural efficiency, varied construction possibilities, both economic and aesthetical benefits, and landscape integration) are set out. Finally, design criteria are included.

Standard Chain Lever Load Binder

2012 ◽  
Author(s):  
Ralph L. Barnett ◽  
Theodore Liber
Keyword(s):  
Boundary Conditions ◽  
Energy Levels ◽  
Product Liability ◽  
Lateral Force ◽  
Complete Analysis ◽  
Safety Hazards ◽  
Force Components ◽  
Cable Forces ◽  
The Cost ◽  
Alternative Designs

The standard chain lever load binder that is used for truck cargo securement operates on an over-center principle that has been used for over a century on suitcases, tool boxes and camera cases. The safety hazards associated with the uses and misuses of the load binder were identified decades ago and various inventors patented innovations that eliminated or mitigated the safety shortcomings. Furthermore, their ideas were not only effective, they were economical, versatile, and efficient. These patents are now in the public domain and many companies manufacture and/or distribute entire lines of securement that include not only the standard chain lever load binder but most of the alternative designs as well. This case study takes the position that the standard chain lever load binder should be banished. Since the appropriate bodies, after all these years, have not arranged for its demise, this paper appeals to the product liability system for safety relief. Engineering analysis and tests are provided to the legal profession to help them protect us by making the cost advantage of the standard binder too expensive. This paper explores some of the remarkable properties of the standard load binder, e.g., • Load binders develop very large chain tensions and very high levels of recoverable energy. The standard chain lever load binder does not enable the tension and energy levels to be safely maintained or released. • The handle slack on the standard load binder cannot be fine-tuned; consequently, a scenario is frequently encountered where the chain is either too loose or too tight to secure with the binder handle. This is the major motivation for resorting to a “cheater bar.” • A complete analysis of the securement forces acting on the cargo and load binder is seldom possible because the system is a “moving target.” The handle loading is randomly applied by human exertion which changes with handle orientation. The boundary conditions depend not only on the cargo and securement strategy, but on the loading itself. Unknown friction characteristics of the loading affect the distribution of chain forces. • On one side of the load binder the chain tension can always be predicted using only the handle torque. This cable tension is independent of the boundary conditions and any axial handle force components. • When the load binder system is rigid, it gives rise to three singularities. The mechanical advantage is unbounded at the two extreme handle orientations. When the binder is suspended in a taut condition, any lateral force on the binder develops infinite cable forces. • Handle slack has a profound effect on the handle resistance, the resilience, the chain tension, and the latching capability.

New Standard for Assessment of Structural Integrity for Existing Load-Bearing Structures-Norsok N-006

2009 ◽  
Author(s):  
Gunnar Solland ◽  
Inge Lotsberg ◽  
Lars G. Bjo̸rheim ◽  
Gerhard Ersdal ◽  
Vidar-Andre´ Gjerstad ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Regulatory System ◽  
Life Extension ◽  
Design Standards ◽  
Load Bearing ◽  
Fatigue Design ◽  
Design Life ◽  
Advanced Analysis ◽  
The Cost ◽  
Existing Structure

An increasing number of platforms in the Norwegian continental shelf are reaching their design life. For various reasons these platforms will require an assessment of their structural integrity. When performing these assessments the engineer is faced with tasks where little guidance is found in design standards, for several reasons. The two most important being: 1) The analyses that is performed in a typical assessment of existing structure is often applying very advanced techniques and methodology that seldom is used in design of new structures, as the cost of doing advanced analysis is relatively low compared to replacement of an existing structure, but relatively high compared to moderate additions of e.g. steel in the design of a new structure. 2) Design standards are based on theories, methods and experience for structures in a given design life (e.g. fatigue design and corrosion protection design). When this design life is extended, sound methods for ensuring that the structures are still sufficient safe is needed. Such methods will normally be “condition based design”, where inspection, maintenance and repairs are included in the assessment in integrated way. Such methods are not given in normal design standards. For these reasons a new NORSOK standard is developed that gives recommendation on how to deal with the specific aspects that engineers meet when performing assessments of structures in general, but also specifically for assessment for life extension. The standard is named “Standard for Assessment of Structural Integrity for Existing Load-bearing Structures” and is issued as a NORSOK standard and given the number N-006 [1]. The topics that are covered in the standard include: Shut down and unmanning criteria for platforms not meeting ordinary requirements, specific issues for determination of ultimate capacities by use of non-linear methods, cyclic capacity checks, fatigue life extension, requirements to in-service inspection etc. The paper describes the background and the content of the new standard and it presents examples of recommendations given. The role of the new standard in the Norwegian regulatory system is shown.

Monitored structural behavior of a long span cable-stayed bridge under environmental effects

2018 ◽  
Vol 4 (4) ◽  
pp. 137 ◽  
Author(s):  
Alemdar Bayraktar ◽  
Ashraf Ashour ◽  
Halil Karadeniz ◽  
Altok Kurşun ◽  
Arif Erdiş
Keyword(s):  
Air Temperature ◽  
Environmental Effects ◽  
Monitoring Data ◽  
Structural Behavior ◽  
Steel Cable ◽  
Daily Monitoring ◽  
Cable Stayed Bridge ◽  
Long Span ◽  
Cable Forces ◽  
Cable Stayed Bridges

An accurate numerical analysis of the behavior of long-span cable-stayed bridges under environmental effects is a challenge because of complex, uncertain and varying environmental meteorology. This study aims to investigate in-situ experimental structural behavior of long-span steel cable-stayed bridges under environmental effects such as air temperature and wind using the monitoring data. Nissibi cable-stayed bridge with total length of 610m constructed in the city of Adıyaman, Turkey, in 2015 is chosen for this purpose. Structural behaviors of the main structural elements including deck, towers (pylons) and cables of the selected long span cable-stayed bridge under environmental effects such as air temperature and wind are investigated by using daily monitoring data. The daily variations of cable forces, cable accelerations, pylon accelerations and deck accelerations with air temperature and wind speed are compared using the hottest summer (July 31, 2015) and the coldest winter (January 1, 2016) days data.

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