NCHRP 20-07 - Transportation.orgsp.bridges.transportation.org/Documents/2014 SCOBS... · DIN 19704...

NCHRP 20-07 Review of the AASHTO LRFD Movable Highway Bridge

Design Specifications for future updates

Progress Presentation to the AASHTO HSCOBS T-8 Subcommittee

April 23, 2014 Columbus, OH

NCHRP 20-07/348, Review of the AASHTO LRFD Movable Highway Bridge Design Specifications for Future Updates

NCHRP 20-07 Review of the AASHTO LRFD Movable Highway Bridge

Design Specifications for future updates

DISCLAIMER: This investigation is sponsored by TRB under the NCHRP Program. Data reported is work in progress. The contents of

this presentation has not been reviewed by the project panel or NCHRP, nor do they constitute a standard, specification, or

regulation.


Presentation Outline

• Research Objectives

• Research Team

• Research Approach

• Update of Current Status

• Open Discussion


Research Objective

The current specifications need updating to incorporate the LRFD method, based on reliability-based design methodology and to reflect advances in mechanical systems, electrical drives and controls, and traffic/marine safety systems. The objectives of this research are to:

• Develop a stand-alone synthesis of the various types of mechanical

systems and electrical controls and drives currently being used in movable bridges

• Identify the areas of the AASHTO LRFD Movable Bridge Design Specifications that require modification, addition, or deletion to incorporate the LRFD method to reflect advances in structural materials and design, mechanical systems, electrical drives and controls, and traffic/marine safety systems

• Propose recommendations for future research needs


The Research Team


LEGEND Parsons Brinckerhoff (*) Steward Machine Company (SMC) James A. Swanson (JS) John Kirchner (JK) HBM Engineering (HBM) Washington State DOT (WSDOT) – Invited formal acceptance pending Florida DOT (FDOT) – Invited, formal acceptance pending

Research Approach


WE ARE HERE

Task 1 – Literature Review

Current Applicable Design Standards - USA

• AASHTO LRFD Bridge Design Specifications, Customary U.S. Units, 7th Edition, 2014 Reliability-Based for Structural

• AASHTO LRFD Movable Highway Bridge Design Specifications (Specifications), 2nd Edition, 2007, with yearly Interim Revisions through 2012 – Not Reliability-Based for Mechanical and Electrical



Other relevant Movable Bridge Design Standards

• CAN/CSA-S6-06, Canadian Highway Bridge Design Code, Chapter 13 – Movable Bridges, Published 2006, Reliability-Based for Structures Not Reliability-Based for Mechanical and Electrical

• AREMA Manual for Railway Engineering, Volume 2 -Structures, Chapter 15 - Steel Structures, Part 6, Not Reliability-Based



International Design Standards – Reliability-Based

Dutch:

• NEN 6786 Rules for the Design of Movable Bridges

• Published 2001. Full revision to be published September, 2014

German: Published Draft 2012, also 1998 version in English

• DIN 19704 Hydraulic Steel Structures

• Part 1: Criteria for design and calculation

• Part 2: Design and Manufacturing

• Part 3: Electrical Equipment


Machine Translation – NEN 6786


DUTCH Voorschriften voor het ontwerpen van

beweegbare bruggen (VOBB)

ENGLISH Rules for the

Design of Movable Bridges

Machine Translation – Dutch to English NEN 6786 – Rules for the Design of Movable Bridges


Foreword:

• “The technical regulations for movable bridges has not kept pace with the developments such bridges, regarding loads, materials, methods of calculation, etc. during the last decades.”

• “The semi - probabilistic calculation method is introduced in NEN 6786 .”



Chapter 1.0 – Subject Matter and Scope

• “1.1 This standard provides technical provisions for the design of mechanical equipment; electrical installation of all types of movable bridges for road and rail traffic. When applying what has been stated in this standard may, for mechanical equipment and electrical installation of a movable bridge, to be assumed that at least one level of security present.”



COMMENTS 1.0 – Subject Matter and Scope “1.1 Through application of the standard is a minimum

reliability index (f3) is reached:

• Ultimate limit state, where wind normative; f3 = 2.6

• Ultimate limit state, if other loads normative; f3 = 3.6

• Serviceability limit state (not BS 6700:1991); f3 = 0.5 ”

Machine Translation – Dutch to English – NEN 6786


“Movable bridges can be distinguished. Six types a logical format is that the nature of the movement:

• Rotation about a horizontal axis: Bascule Bridge Bang Bridges Draw Bridges Strauss Bridges Certain construction equipment for ferries

• Rotation about a vertical axis: Turn Bridges Crane Bridges

• Horizontal translation: Travelling Ship or float bridges

• Vertical translation: Car lifts

• Rotation about a horizontal axis, Rolbasculebruggen together with a horizontal translation

• Rotation about a horizontal axis, Certain construction equipment for ferries” together with a vertical translation

Machine Translation – German to English DIN 19704 – Hydraulic Steel Structures


“The standard is applicable to the calculation and design of steel hydraulic structures consisting alls Constructions of slahlballs, mechanical engineering and electrical equipment.”

“The standard also applies to … bollard and swimming Sloßschutzeinrichtungen and for canal bridges.”

Machine Translation – German to English DIN 19704 – Hydraulic Steel Structures


• Word search: No hits for “Reliability” or “Probability”

• For Mechanical and Structural calculation:

• Ultimate Limit State

• Limit State of Serviceability

• “9.5.3 Proof of fatigue”

• “For machine parts and their electrical equipment, except the wearing parts (eg, ropes and Sockets in Lasch Celts) is assumed a useful life of 35 years.”

Task 2 – Synthesize the Various Types of 1) Mechanical Systems and 2) Electrical Drives and Controls

Coordinate with:

• NCHRP 14-32: Task 7 – Develop Standardized Descriptions for Inventory and Inspection on Element Level



Types of Movable Bridges:

• Bascule (including rolling-lift)

• Vertical Lift

• Swing

• Other/Specialty/Uncommon Types



• Support

• Balance

• Drive

• Control

• Interlocking

• Navigational Guidance

• Traffic Control


Per Section 2.2.1 of the AASHTO Movable Bridge Inspection, Evaluation and Maintenance Manual, 1998

Functional Systems of Movable Bridges


Preliminary List of Support System Components:

• Bascule Bridges: trunnions, trunnion bearings, live load shoes, and sometimes locks. Tread plates and tracks for rolling-lift.

• Swing Bridges: center bearings, rim bearings, wedges, end lifts, and balance wheels.

• Vertical Lift Bridges: sheaves, sheave shafts (trunnions) and bearings, counterweight ropes, live load shoes, span guides.



Preliminary List of Balance System Components:

• Bascule Bridges: counterweights. Also counterweight linkages for Strauss and Dutch type bascules

• Swing Bridges: counterweights (when applicable)

• Vertical Lift Bridges: counterweights, auxiliary counterweights, and ropes.



Preliminary List of Mechanical Drive System Types

• Gearing: Open or Enclosed

• Hydraulic Cylinder

• Hydraulic Motor

• Wire Rope Drive

• Load Sharing: differential, electric load sharing, hydraulic, non-load sharing

• Movers: electric motor, pneumatic motor, internal combustion, and human powered



Preliminary List of Control System Components:

• Electrical

• Relay Based Controls

• Programmable Logic Controllers

• Direct Digital Control

• Hybrids

• Mechanical

• Buffers


Task 3 – Discuss the Application of Reliability-Based Design to Mechanical, Electrical, and Traffic/Marine Safety Systems for Movable Bridges


Calibration of the Reliability Index (β)

• Goal: Uniformity of Safety & Failure Probability

• Bridge Structures: β= 3.5 (Standard Deviations)

• Probability of 2 in 10,000 for member failure

• Probability of 1 in 1,000,000 for bridge failure

• Compares well with 600,000 bridges in US inventory


For Mechanical, Electrical, and Traffic/Marine Safety Systems

• How to define failure?

• What is a tolerable probability of failure?

• What, historically, have been the causes and consequences of failures?

• What additional (non-historical) failures can be anticipated?

• What is the probability of failure of existing systems, designed per existing AASHTO and International standard? Is this acceptable?


Case Histories – Failure of Mechanical, Electrical, and Traffic/Marine Systems

• Shippingsport, IL (1978) Trunnion fracture

• Hackensack River, NJ (1928) Strauss Counterweight Link

• Evergreen, WA (1980’s) Electrical fault opening

• Hood Canal, WA (2005) PLC fault opening


Case Histories – Failure of Mechanical, Electrical, and Traffic/Marine Systems

• Burlington Canal, ON (1980’s) Electrical fire – bridge closed

• First Ave S, WA (1990’s) Air in Hydraulics, Control Lost

• LaSalle, ON (1980’s) Traffic Gate Fault Operation

• W. Jefferson, MI (2013) Operator Error – Drunk


Non-Structural Reliability

The reliability of a component during any time period can be expressed as

where

• R varies between 0 and 1, with 1 indicating 100% live components.

• = proportional failure rate of a component

• t = time


tR e

The Reliability of a Component:


The reliability of a system of components in series is:

where

• Rs is the system reliability

• R1, R2, Ri are the reliabilities of the system components

• s = proportional failure rate of a the system s = i

• t = time


... ...s 1 2 i nR R R R R

st

sR e

The Reliability of a System in Series:


The mean time to failure of a system of components in series is:

where

• = mean time to failure (MTTF) of a system

• s = proportional failure rate of a the system s = i


1

s


The reliability of a system of components in series is:


The Reliability of a System in Series:

R1 R2 R3 R4


The reliability of a system of components in parallel is:

where

• R1, R2, Ri are the reliabilities of the components that form the system.


21 1 1 ... 1 ... 1s 1 i nR R R R R

The Reliability of a System in Parallel:


The reliability of a system of components in parallel is:


The Reliability of a System in Parallel:

R1A

R1B

R1A R1B

R2A

R2B

R2A = R2B = R2C

R2C



The Reliability of a Combined System:

R1A

R1B

R2A

R2B

R2C

R1 R2 R3 R4


• Cost of Failure: • Bridge Stuck “Closed” – Cost of Under-Passing Traffic Being Blocked (Channel Navigation)

• Bridge Stuck “Open” – Cost Related to Overpassing Traffic Being Blocked (Roadway Traffic)

• Bridge Stuck “In-Between” – Cost of All Traffic Being Blocked (Channel and Roadway)

• Time of Repair: • Consider On-Site Storage of Critical Replacement Components

• Cost of Maintenance: • If the Components are Inexpensive or Unreliable, Replace Them More Frequently

• Parallel Subsystems: • Redundancy Increases Reliability but also Increases Cost


Factors for Consideration:


• Collect Failure Rate Data for Drive Components • Varies by Bridge Type and Configuration

• Manufacturer Data, Experience of Bridge Owners

• Determine Project-Specific Cost Indices Associated with Loss of Service • Operational Importance of the Bridge, ADT, ADTT

• Operational Importance of the Underlying Navigation Channel, National Security

• Determine an Acceptable Level of Reliability for the Lifting System • Balance Initial Cost and Life-Cycle Cost with Costs Associated with Loss of Service

• Recommendations for Design and Maintenance of Lifting System • Parallel Subsystems Where Necessary

• Determine Maintenance Intervals for the Lifting System

• Recommendations for Routine Replacement/Service of System Components

• Contingency Plans of Action for Expedient Repair of Failed Components


Approach for Code Development:

Task 4 – Outline Proposed Areas of AASHTO LRFD Movable Bridge Design Specifications for Future Modification, Addition, and Deletion

Proposed Outline:

1. General Provisions

2. Structural Design

3. Mechanical Design

4. Electrical Design

Appendix

Index


• Research Objectives

• Research Team

• Research Approach

• Update of Current Status

• Open Discussion

Presentation Recap


WE ARE HERE

Open Discussion


• Does your agency collect movable bridge failure rate data?

• Does your agency collect project-specific cost indices associated with loss of service?

• What is the acceptable level of reliability for movable bridges?

Comments


• Mike Abrahams [email protected]

• Scott Snelling [email protected]

• Mark VanDeRee [email protected]

mailto:[email protected]



Reliability Approach to Movable Bridges

Structural Components

• Probability of Failure is Based on Load and Resistance

• “Physics of Failure” Theoretical Basis

• Failure Could Result in a Catastrophic Collapse

• Consequence of Failure Could be Loss of Life

• “Safety Engineering” Approach to Design and Inspection

Unique Structural Aspects

• Cantilever Dead Load Patterns for Bascule and Swing Bridges

• Locking Mechanisms for Shear and Moment in Bascule Bridges

• Structural Design of Drive Components

• Additional Load Combinations / Analysis Configurations (Open vs Closed)

Difference Between Reliability of Structural vs Non-Structural Components


Reliability Approach to Movable Bridges

Non-Structural Components

• Probability of Failure is Based on System Reliability of Lifting Components

• “Parts Stress Modeling” Theoretical Basis

• Failure Not Likely to Result in a Catastrophic Collapse

• Consequence of Failure is Likely Loss of Service / Economic Loss

• “Reliability Engineering” Approach to Design and Maintenance

Difference Between Reliability of Structural vs Non-Structural Components


Structural Reliability

• = Adjustment Factor ( =1.00 for = 3.0)

• = 0.0062 2 – 0.131 + 1.1338

• Rm = Mean Value of Rm (from experiments)

• Rn = Nominal Value of R (design calculation)

• R = Variable to Separate the Variability of Resistance from Load

• = Reliability Index

• VR = Coefficient of Variation of Rm


Resistance Factor: R RVm

n

Re

R


• Alternatively, the resistance factor can be written as

• R is referred to as a bias coefficient and is taken as the ratio of Rm to Rn

• Factors that enter into the determination of R include the possibility of material understrength, the possibility of geometrically undersized members, and the accuracy of the equations and models used to calculate strength (professional factor).

• The appeal of this approach is that the different factors can be addressed individually, and then combined in end.


R RV

R e

Resistance Factor:


These factors can be treated individually as:

• M = Bias Coefficient for Material Strength • G = Bias Coefficient for Cross-Sectional Geometry • P = Bias Coefficient for Professional Factor

• Their coefficients of variation can be treated individually as:

• VM = CoV for Material Strength • VG = CoV for Cross-Sectional Geometry • VP = CoV for Professional Factor


R G M P

2 2 2+ +R G M PV V V V


Given varying system configurations and component reliabilities/failure rates, system design and maintenance requirements can be based on a required system reliability, balancing cost and level of service.


The Reliability of a Component:

• Bascule Bridges • Single Leaf

• Double Leaf

• Swing Bridges • Center Bearing

• Rim Bearing

• Vertical Lift Bridges • Span Drive

• Tower Drive

• Electrical Supply

• Control Systems

• Motors / Hydraulic Pumps

• Gear Mechanisms / Hyd Systems

• Traffic Safety Subsystems

Date post:	26-Mar-2020
Category:	Documents
Upload:	others
View:	17 times
Download:	0 times