Bridge News Archive
|TAEG 2.0 - CORRECTED ERRORS AND CHANGES|
Discrepancies were detected in the TAEG 2.0 results at the end of June 2004. These discrepancies were determined to be in need of fixing and after a detailed investigation of the code, the errors were found. It was also determined that the errors were significant enough to necessitate an updated version and re-release of the program. This provided an opportunity to improve other aspects of the program, as well.
The following is a description of the corrected errors and other changes to the program:
WHEEL LOAD RESET:
An error was detected with the "Wheel Load" output on the "Calculated Bracket Forces" form. While conducting several, similar examples with minor adjustments to the "Bracket Spacing" on the "Bracket Data" form and the "Wheel Spacing" on the "Load Data" form, it was apparent that the "Wheel Load" output was not changing.
Code was added to TAEG 2.1 to reset the "Wheel Load" for each separate calculation. The problem in TAEG 2.0 was that the "Wheel Load" output would not change from calculation to calculation if the most recent calculation produced a result less than any of the previous runs. This is because code was in place to find the worst case scenario or ultimate wheel load for a bracket, which is the conservative approach. Therefore, the only way to ensure getting the correct result was to exit out of the program and restart TAEG for each separate example. Obviously, this is not ideal. The nature of the program encourages minor adjustments and tweaking of a bridge's support systems in order to obtain the most desirable results. Thus, it was necessary to identify the problem, determine a solution, and test the new code for accuracy.
Another error detected in TAEG 2.0 also dealt with the "Wheel Load" output on the "Calculated Bracket Forces" form. While conducting examples in English or "U.S. Customary" units, it was apparent that the results were not even close to what they should have been. However, when the results were converted to Metric or "S.I." units, using the "Units - Change S.I. to U.S. Customary" option in the main pull down toolbar, the answers was correct. After investigation of the code, the cause of the error was found in the unit conversion factors.
All internal calculations within TAEG, regardless of the input units, are conducted in base units of kilonewtons (kN) and meters (m). Therefore, it is necessary to convert all input variables and to then convert all output results back to the desired units. The "Wheel Load" output in "U.S. Customary" units was determined to be in the form of "Load per Unit Width" (kips/ft.) rather than just "Load" (kips). Therefore, to get the correct results, simply multiply the "Wheel Load" output in "U.S. Customary" units by the conversion factor for meters to feet or "3.28083989501." Incidentally, the reason the "Wheel Load" output was correct when the units were converted to "S.I.", is that there is no internal conversion necessary for loads; i.e., input load units are kN and output load units are kN.
The other changes made to the program were improvements to make it more user friendly. Here is a brief list of some of those changes:
o "Stresses Due to Non-Composite Dead Load" on the "Load Data" form
o All output on the "Calculated Stresses" form
o "Maximum Stress in the Diaphragm Due to Torsional Load (M)"on the "Calculated Lateral Support Response" form
Our goal was to correct any errors that were found and to make the program better overall. We hope that we accomplished both goals. We would appreciate any comments or suggestions for any future releases. The contact person for any questions or comments regarding TAEG is:
|USGS Stream Statistics Project|
This is a website for the USGS stream statistics project that has been completed and made public. There are updated estimates of flows at many of the stream segments in Kansas. The flow estimates are for both median daily and peak flows.
In addition, Real-Time Streamgage information can be viewed at: http://waterdata.usgs.gov/nwis/rt
|KDOT INFLATION TABLES (UPDATED)|
The following Adobe PDF document, (Dated: 5/24/2004) contains the current KDOT Inflation Tables .
|BOLTED SPLICE UPDATE|
For Steel Bridge Projects that have a letting date after July 1, 2004, all bolted connections will use English bolts (and bolt holes) only.
All shop drawings for lettings after July 1, 2004 shall specify English bolts with the corresponding English holes.
Accomplish this on the plans by one of the following methods:
|APPROACH SLAB JOINTS|
There are two types of joints allowed in the Bridge Approach Slab: Type B (Two-Part Silicone) and Type C (Preformed Elastomeric Neoprene) as shown on KDOT Standard Drawing RD662 SI. The maximum allowable gap width for the Type B Joint is currently shown as 75 mm. This maximum allowable gap width (for the Type B Joint only) is being reduced from 75 mm to 40 mm. Therefore, for plans currently under design, make the necessary change on Standard RD662 SI until it is revised.
|DESIGN OF BOLTED SPLICES DURING THE TRANSITION FROM METRIC TO ENGLISH|
Projects that are surveyed in metric will continue to be designed, detailed and constructed in metric. One exception to this policy concerns bolted splices on steel girder bridges. Since the supply of metric bolts will eventually be exhausted, English bolts will have to be used. Therefore, design bolted splices on metric jobs assuming US Customary bolt sizes (7/8' bolts for main members; 3/4' bolts for secondary members). However, detail the bolted splices assuming metric bolt sizes (M24 bolts for main members; M20 bolts for secondary members; spacing; edge distances, etc.).
Place a note on the bolted splice detail sheet immediately above the revision block. The note shall read as follows: Bolted splices have been designed for USC substitution.
If the supply of metric bolts is exhausted and plans still exist that are detailed using SI Metric-designed bolted splices, these splices will need to be checked/redesigned for the substitution of USC for SI Metric bolts. The shop details must reflect the changes.
|INVERTED TEE REINFORCEMENT|
Use the stirrup details shown in the attached PDF file for Prestressed Inverted Tee sections. Epoxy coat the stirrups.
|Bridge Restrictions Map|
The new and updated Bridge Restrictions Map is now available.
|Teflon Bearing Devices|
Recess all horizontally installed polytetrafluoroethylene (PTFE) surfaces for Bearings into its steel substrate by one-half of the PTFE's thickness. Use a PTFE thickness of 6 mm. This will prevent any excessive creep or plastic flow of the PTFE from occurring which could lead to separation or bond failure. In addition, confining the PTFE permits the use of a higher contact stress. The maximum exposed thickness of 3 mm will also give the longest wear life.
Steel for Pins used in Steel Bearing Devices
For pins used in the construction of steel bearings, specify ASTM A 108 Gr.1018 for pins 100 mm or less in diameter.
For pins greater than 100 mm, Article 6.4.2 of the AASHTO LRFD Bridge Design Specifications (2nd Ed.), specifies steel forgings as per ASTM A 668M. Steel forgings are not guaranteed to be weldable, therefore only use the A 668M specification for pins that are not to be welded.
For pins greater than 100 mm that are to be welded, specify ASTM A 572M Gr. 290 (max 150 mm plates) or Gr. 345 (max 100 mm plates). Two plates can be welded together in the shop and machined into two half pins. Therefore, two 150 mm plates can produce two half pins with a maximum diameter of 300 mm. Likewise, two 100 mm plates can produce two half pins with a maximum diameter of 200 mm.
|Haunched Slab Standards|
Beginning with Field Checks in February 2003, all new Haunched Slab Bridges on the State System will use the standard superstructure design that includes the Kansas Overload Provision. Consequently, the substructure must also be designed to include this additional load.
Kansas Department of Transportation Secretary, Deb Miller has decided that Kansas will go back to the English system of measurement. However, if a project has been started in metric, it will be completed in metric. The process for conversion will be set up soon. Details to follow.
|TAEG (Torsional Analysis of Exterior Girder) Version 2.0|
The State Bridge Office (SBO) has released TAEG (Torsional Analysis of Exterior Girder) V. 2.0 for use in the review of overhang false work for beam\slab or girder\slab bridge structures during deck placement. This version has expanded boundary conditions to facilitate skews and discontinuous cross-frames or diaphragms. The software (design tool) is being distributed on CD and includes the abstract, final report and a users manual that can be used as a tutorial. Initially, this CD will be sent to current users (those registered in the SBO data base).
This software is available by request through the KART. This version, like the previous versions, is not structural analysis software and therefore will not calculate spatial structural responses due to dead loads or other non-composite effects. These values are inputted into TAEG 2.0 and the torsional effects are superimposed to give the total effect.
|NEW REQUIREMENTS FOR "CONTRACTOR STAKING"|
Special Provision 90M - 260 "Contractor Construction Staking" has been revised (R1). When staking for bridges, the specifications now call for two independent surveys. In order to alert the Contractors of this change, place the following note on the "General Notes and Quantities" sheet immediately under the table of bid items:
** Contractor Construction Staking for bridges requires two independent surveys.
(This change is in effect for Projects let in the July, 2002 letting.)
|CONCRETE NOTE CHANGE - "CLASS" TO "GRADE"|
The Bridge Office Standard Drawings have been revised to show all concrete as "Grade" instead of "Class".
|KDOT POLICY FOR SHOP DRAWING PROCEDURES|
KDOT has developed a document that sets policy for the distribution of shop drawings. The document's intent is to provide uniformity for handling shop drawings related to bridges. The document covers both KDOT and Consultant-designed jobs for main and secondary-system bridges. The new procedures in this document will eliminate delays, unnecessary paperwork, and confusion caused by the use of different procedures by designers and fabricators. KDOT solicited input from the consultant community and from fabricators when developing this document.
Consultants and fabricators working for KDOT will follow these procedures.
|SHEAR STUDS TO BE APPLIED IN THE SHOP|
OSHA has ruled that if fall protection is provided, studs may be shop applied. When studs are shop applied, the Bridge Office feels we get a better product at less cost, therefore we will revert to requiring studs be applied in the shop. Notes and Specifications will be modified to reflect this revised policy. Squad Leaders will be contacting those Consultants who have steel girder jobs nearing completion.
|AMENDED METRIC POLICY|
Amendment to the metric policy, use of metric bolts.
|SHEAR STUDS TO APPLIED IN THE FIELD|
On all new steel girder bridges that require shear studs on the top flange, place a note on the plans specifying that the studs are to be applied in the field. This applies whether or not the steel girders are let early. Standard Notes to follow.
|POST-TENSIONED HAUNCHED SLABS|
The PT slab details are being updated. Therefore it is important to request the most current set of standard details available. Do not use a set that is on your office server that may be only a month old. They may no longer be up to date. Request the most current set of standards from a Squad Leader in the State Bridge Office, or from the Post-Tensioned Slab Request form on the Internet, or from the Bureau of Local Projects.
|Environmental Spreadsheet Advisory|
The Environmental Spreadsheet Advisory, is information furnished for KDOT projects to aid in the completion of the "Permit Spreadsheets" that are required by the Environmental Services Section (ESS) of KDOT. The information is offered as practical examples and are not documents, regulations, or policies issued by, or authored by the Kansas Division of Water Resources or the Army Corps of Engineers. The spreadsheets are not a substitute for the "Hydraulic Assessment Checklist" that is required for all bridges and '500' Series Culverts.
|Use of temporary fence during overpass construction over the Burlington Northern Santa Fe Railroad|
The BNSF RR has requested that we no longer use the temporary fence during overpass construction. Therefore,effective immediately, for a bridge over the BNSF RR, remove all details and the bid item for "Temporary Fence" from the plans. Note 8310 "Temporary Fencing" will also be deleted from the Standard Notes.
|Overhang Design for Rail Collision Forces using STAAD Finite Element Model|
|Post-tensioned Haunched Slab Class|
There will be a Post-tensioned Haunched Slab Class, at the KDOT- District 1 Office, on March 21, 2001.
|On-line PDH course for "Use of Uncoated Weathering Steel in Bridge Structures"|
For a limited time, bridge engineers can earn free PDH units on-line at http://www.PDHonline.org/s108aisi.htm.
For other free online courses, please visit http://www.PDHonline.org.
|"Estimation of Peak Streamflows for Unregulated Rural Streams in Kansas"|
The USGS report, Water-Resources Investigations Report 00-4079, "Estimation of Peak Streamflows for Unregulated Rural Streams in Kansas", has been adopted by KDOT as an acceptable method for computing frequency-discharge flows on KDOT bridge projects. Runoff relationships are published for drainage areas from 0.17 sq.mi. to less than 30 sq.mi. and from 30 sq.mi. to 9,100 sq.mi. Copies of the report along with the Errata Sheet dated August 21, 2000, may be obtained from either of the following:
|The following Standard Notes have been revised since 9/05/00.|
NOTE 1110 SONIC TESTING
(Place this note on all bridges with drilled shafts.)
NOTE 3010 ERECTION ELEVATION CHECKS
(Place this note on all prestressed beam bridge plans)
NOTE 4300 SLAB ELEVATIONS
(Place this note on all haunched slab bridges.)
NOTE 9100 CONSTRUCTION LOADS
(Place this note on all bridges.)
See Standard Notes
|Revision to RCB Program (Wing Details)|
It had been brought to the attention ot the Bridge Office that several long wingwalls on skewed box culverts were cracking shortly after they were constructed. Sometimes this occurred even before the wingwalls were backfilled. Cracking was most severe where the wingwall attached to the box.
To help alleviate this problem, the Bridge Office decided to make the wingwalls on certain skewed boxes freestanding.
It was noted that normal boxes up to 3.05 m high typically did not experience any distress. The wingwall length on a 3.05 m normal box is 6.25 m. Thus it was determined to make all wingwalls over 6.5 m in length freestanding.
This effects the following box culverts:
This revision is scheduled to take place on September 12, 2000.
It is not necessary to replace existing affected box details with the new freestanding wing details.
|LRFD Foundation School|
KDOT has hosted this school (C-13068 See LRFD Training Page) twice. Some who were unable to attend have asked if we might host it again.
|DESIGN OF ELASTOMERIC BEARING DEVICE USING METHOD "A"|
Information concerning the equation in the AASHTO LFD and LRFD Specifications for checking rotation when designing Elastomeric Bearings according to Method "A". This Adobe Acrobat file contains information that replaces the incorrect LFD equation 126.96.36.199.5-1 and LRFD equations 188.8.131.52.5 -1 & 184.108.40.206.5 -2.
|BRASS/AASHTO OPIS LRFD PRESTRESSED I-GIRDER SCHOOL|
This training will concentrate on the LRFD implementation of prestressed girders, (simple for dead load, made continuous for live load) in the Wyoming Department of Transportation's BRASS program. This is not a software class. The class will focus on the new LRFD Specification, and the analysis methods and design assumptions that are used in the BRASS program.
|DIRECTIONS FOR WORKING WITH THE RAILROADS|
Information concerning the KDOT Bridge Checklist Submittal to Railroad form has been added to the Bridge web page.
|SPIRAL COLUMN REINFORCING QUANTITY CALCULATIONS|
Tables used to calculate spiral cage quantities are found in the latest version of the Bridge Design Manual (the CD) in Appendix D, Attachment D-4. Please destroy any old hard-copy versions of these tables.
|MEMO TO CONSULTANTS AND GEOLOGISTS|
All engineering consultants and geologists that work on federal-aid bridge projects administered by KDOT are invited to attend a meeting to discuss possible geology policy revisions. This is an opportunity for you to have input concerning these revisions. Engineering consultants are asked to notify and encourage geologists that they work with to attend. KDOT geologist and geotechnical engineers will be in attendance.
The meeting will be held on January 6, 2000 from 10 AM to 3 PM at the Kansas National Guard Armory, State Defense Building, 2800 South Topeka Blvd. in Topeka.
|SI BOLTING - UPDATE|
The following policy applies to January, 2000 lettings and later:
The State Bridge Office will require SI bolts and bolt holes (We mean it this time). Substituting US Customary bolts and holes will no longer be allowed on the shop details. Use M24 heavy hex structural bolts for main member connections. Use M20 heavy hex structural bolts for secondary member connections. KDOT will standardize on the M24 and M20 bolts. Do not use M22 bolts.
Use Direct Tension Indicators (DTI) on all high strength bolts. The State Bridge Office is developing standard notes and Special Provisions. DTI's are not required on anchor bolts.
Standard notes, grip tables, etc. will be made available on the net as they become available.
US Customary bolts may still be used in repair/rehab work when it is the logical action.
|Torsional Analysis of Exterior Girders (TAEG)|
|The final version of TAEG (Version 1.5) and the final report is complete. Some Consultants may have an older version of the software and documentation. Please get Version 1.5 if you are investigating an exterior girder for torsional loads during construction. |
|State Bridge Office Email List|
The State Bridge Office would like to create an Email directory of Consultant bridge designers for our internal use. The list would be posted on our Intranet, therefore only KDOT staff would be able to access it, so you should not get hit by salesmen or headhunters. If you would like to have your staff added to our list, please Email names and addresses to us.
|Post-tensioned haunched slab class|
|Consultants and local governments should sign up for the post-tensioned haunched slab class to be held on May 28th 1999. |
|POLICY: Electronic KDOT Metric Bridge Manual|
|The KDOT Bridge Office will be distributing hard copy revisions to the Bridge Manual in late February, 1999. These will be the last hard copy revisions to the Manual. The KDOT Bridge Office is planning to move the KDOT Metric Bridge Manual to an electronic format (CD-ROM) in the near future. It is anticipated that revisions made in the summer of 1999 will be on CD only. Current Manual owners, upon request, will receive a CD of the entire Metric Bridge Manual including the new revisions, free of charge. New Manual orders will only be available on CD at a cost of $25.00 each. Further instructions will be sent to all Manual Owners with the February revisions. |
|"BOXCAR" PRECAST BOX DESIGN SOFTWARE|
|"BOXCAR" software used by the precast box industry has been updated and is now acceptable for use on KDOT projects. Any BOXCAR version later than "BOXCAR Version 1.95" is acceptable. KDOT will modify page 3-327 of the KDOT Metric Bridge Manual to reflect this policy. |
|SPECIAL PROVISIONS ARE NOW ON THE INTERNET|
|Copies of KDOT Special Provisions are available on KDOT's web page. Drill down through "Doing Business", "Information for Design Consultants", and "Special Provisions". Or follow this link to Special Provisions and bookmark it! |
|AASHTO LRFD Bridge Construction Specifications, 1st Edition, 1998 (SI)|
This Specification is now available from AASHTO. Contact AASHTO at (202) 624-5800 or at the AASHTO Web Page:
|AASHTO LRFD Bridge Design Specifications, 2nd Edition, 1998|
|This Specification is now available from AASHTO. The specifications are available in both US Customary and SI Units. Contact AASHTO at (202) 624-5800 or at the AASHTO Web Page: |
|SI DETAILING PRACTICE CHANGE|
|The KDOT State Bridge Office has changed detailing practice for four-digit SI numbers. In the past, we suggested that the blank space holder be used on all number greater than three digits. We have omitted the blank space holder on four-digit numbers for clarity. Five-digit numbers retain the blank space holder|
We will change our standard details during normal maintenance. We do not intend for anyone to spend time reworking projects that are already partially detailed under the previous nomenclature.
|AASHTO Guide Specification for Design of Pedestrian Bridges|
|This Guide Specification, dated August, 1997, is now available from AASHTO. Contact AASHTO at (202) 624-5800 or at the AASHTO Web Page: |
|SPECIAL PROVISION 90M-165-R4 (10-26-96)|
SECTION 703 - REINFORCING STEEL Page 428, Subsection 703.04, TABLE 1 is deleted and is replaced with a new TABLE 1 with a footnote
The footnote has caused some confusion...
If plans were prepared with pre-1995 SI Metric rebar (10, 15, 20, 25, 30, 35, 45, and 55) the 10M bar cannot be converted without knowing the bars usage.
If it is not obvious how to convert the 10M bar, contact the State Bridge Office.
|SPECIAL PROVISION 90M-6042 (8-2-96)|
PROJECT SPECIFICATIONS - CONCRETE
If structural concrete is designated as Class AAA or Class AAA(AE) Concrete on the plans, furnish concrete as per the Standard Specifications for such. NOTE: The f'c should be shown as 28 MPa on the plans. If f'c is shown as 30 MPa, the above still applies.
This includes RCB standards, and US Customary plans designed for f'c = 4 ksi which have been converted to SI Metric.
If structural concrete is designated as Concrete (Grade 30) or Concrete (Grade 30)(AE) on the plans, furnish concrete as per this Special Provision.
This includes all new designs using f'c = 30 MPa. New designs after 8-29-95 are to use SI Metric concrete grades. (See SI Procedure Update Memo 95.8.3 8-29-95)
NOTE: The UNIT STRENGTH noted in the lab mix design requirements is intended to produce a field concrete which meets or exceeds the f'c Grade required about 98% of the time. In other words, the lab mix design is at least two standard deviations above the f'c Grade requirement.
|REINFORCING STEEL YIELD STRESS|
The KDOT State Bridge Office will use Fy = 420 MPa for new designs effective January 1, 1997. (Previously KDOT had published Fy = 400 MPa) ASTM has adopted 420 MPa. AASHTO has begun the process, but has not finalized the change yet.
Plans let after July 1, 1997 should show Fy = 420 MPa. Consultants will need to change plan notes, bid items, etc. to reflect this change on plans let after July 1, 1997. The State Bridge Office is in the process of updating Standard Plans and notes.
|NHI 13061 - LRFD CLASS VIDEOS AVAILABLE|
|Video tapes of the LRFD class presented at Kansas University and telecast to four satellite sites are available for $995. This class was 4.5 days in length. |
|POLICY: REINFORCING BAR SET ADOPTED BY KDOT|
"Old" Standards (RCBs, RCSH, inlets, etc.) will continue to use the ASTM A615M-94 (Canadian Bars) until the Standards are replaced with revised sheets.
Future "custom" designs will use the ASTM A615M-96 (soft converted US Customary Bars) for pay mass and bar bending.
"Custom" designs should begin converting to the -96 nomenclature, bending and clearance dimensions, and pay mass. Lettings in calendar year 1997 will require an "exception" to be granted.
KDOT Special Provision 90M-165-R4 "REINFORCING STEEL", allows for both Bar Sets, and "Pay Mass" is as shown on the Plans.
Added 10/14/96, Modified 8/13/97
|POLICY: STANDARD SPECIFICATIONS FOR HIGHWAY BRIDGES (16TH ED - 1996)|
|The 16th Edition of the Standard Specifications for Highway Bridges is the accepted standard of the State Bridge Office. Plan details and notes should be revised to reflect the 16th Edition. Lettings in calendar year 1997 will require an "exception" to be granted. |