A354BD Rods Testing Program A354BD Rods Testing Program Current - - PowerPoint PPT Presentation

▶
a354bd rods testing program a354bd rods testing program
SMART_READER_LITE
LIVE PREVIEW

A354BD Rods Testing Program A354BD Rods Testing Program Current - - PowerPoint PPT Presentation

Apr 06, 2024 289 likes •541 views

August 28, 2014 Toll Bridge Program Oversight Committee A354BD Rods Testing Program A354BD Rods Testing Program Current Results 1 Thursday, 8/28/2014 Fastener, Materials, & Corrosion Specialty Consultants Alan Pense, Ph.D., NAE Herbert

slide-1
SLIDE 1

A354BD Rods Testing Program

August 28, 2014 Toll Bridge Program Oversight Committee

1 Thursday, 8/28/2014

A354BD Rods Testing Program Current Results

slide-2
SLIDE 2

Fastener, Materials, & Corrosion Specialty Consultants

Alan Pense, Ph.D., NAE Herbert E. Townsend, Ph.D., P.E. Louis Raymond, Ph.D., P.E. Douglas E. Williams, P.E. Karl H. Frank, Ph.D., P.E. Jeffrey Gorman, Ph.D., P.E.

2 Thursday, 8/28/2014

Thomas Langill, Ph.D. Robert Heidersbach, Ph.D., P.E. Sheldon W. Dean Jr., Sc.D., P.E.

slide-3
SLIDE 3

A354BD Rods at E2 — Break Locations

Location

  • f Breaks

March 2013

2010 — 24Rods

2010 — 24 Rods 2008 — 48 Rods

3 Thursday, 8/28/2014

slide-4
SLIDE 4

ASTM A354 Grade BD Rods Across SFOBB-SAS

4 Thursday, 8/28/2014

slide-5
SLIDE 5

A354 BD Galvanized Bolts

Location Item No. Description Quantity Installed Diameter (in) Tension (Fraction

  • f Fu)

Average Hardness 1 2008 Shear Keys Anchor Rods – Bottom (S1/S2) 96 3 0.70 37 2 2010 Shear Keys and Bearing Rods 192 3 0.70 34 Pier E2 y g 3 Shear Key Anchor Rods – Top 320 3 0.70 35 4 Pier E2 Bearing Rods – Top Housing 224 2 0.70 35 5 Spherical Bearing Bushing Assembly Bolts 96 1 0.61 36 6 Bearing Retainer Ring Plate Assembly Bolts 336 1 0 40 35 6 Bearing Retainer Ring Plate Assembly Bolts 336 1 0.40 35 Anchorage 7 PWS Strand Anchor Rods (Main Cable) 274 3-1/2 0.32 35 Top of Tower 8 Tower Saddle Tie Rods 25 4 0.68 35 9 Tower Saddle Turned Rods (@ Splices) 108 3 0.45 37 p 10 Tower Saddle Grillage Bolts 90 3 0.10 34 11 Tower Outrigger Rods 4 3 0.10 39 Bottom of Tower 12 Tower Anchorage Anchor Rods (75 Dia. Anchor Rods) 388 3 0.48 34 13 Tower Anchorage Anchor Rods (100 Dia. Anchor Rods) 36 4 0.37 33 East Saddles 14 East Saddle Anchor Rods 32 2 0.10 37 15 East Saddle Tie Rods 18 3 0.20 33 East Cable 16 Cable Bracket Anchor Rods 24 3 0.16 36 Pier W2 17 Bikepath Anchor Bolts at Pier W2 43 1-1/4 N/A 36

5 Thursday, 8/28/2014

Pier E2 (New) 18 E2 2013 Replacement Rods (CCO 312) 8 3 0.70 35

slide-6
SLIDE 6

Testing Program Objective

  • F rther in estigation of the fract re
  • Further investigation of the fracture
  • f the A354BD threaded rods.
  • Evaluate if other A354BD threaded

rods require modifications rods require modifications.

6 Thursday, 8/28/2014

slide-7
SLIDE 7

Testing Program Summary

TEST NO. TEST NAME TEST PHOTO TEST PURPOSE AND DESCRIPTION

I

Field Hardness Test (in-situ) Hardness is a factor known to affect the stress corrosion cracking susceptibility of high strength low alloy steels. Therefore, to evaluate stress corrosion cracking susceptibility of the A354 BD rods in service, it is necessary to measure and characterize the hardness of the in-situ rods and bolts. Test I is an in-situ hardness test on all accessible A354 grade BD rods and bolts on the Self Anchored Suspension Span. Measurements were then g p p taken across the rod or bolt diameter using an ultra sonic contact impedance hardness tester.

II

Laboratory Tests: Hardness, Charpy, and Chemistry

  • 1. Laboratory hardness is performed as a verification of the field hardness measurements in Test I.
  • 2. Toughness (Charpy V-Notch) testing and determining the chemical composition are to characterize the material.

The test specimens were either cut from the stick-out of installed rods or they were cut from spare rods that were manufactured in the same lot as the rods being evaluated.

III

Full Size Tension Test This test is to verify the full-diameter tensile capacity of A354BD rods and bolts vs. typical reduced size tensile test results. Full-diameter specimens are tension tested in a laboratory and supplemented by laboratory testing for: reduced size tension test; Rockwell C hardness; toughness (Charpy V- Notch); and chemistry, as well as fracture surface examination and analysis. Test specimens were either extracted from the structure (after analysis confirmed that the capacity of the connections were still acceptable), or from spare rods that were manufactured from the same lot as the rods being evaluated.

IV

Full Diameter Rod Stress Corrosion Test (Townsend Test) Using full-diameter samples, the stress corrosion cracking thresholds are established for A354BD rods from different material heats and manufactured by different methods. Test IV (Townsend Test) is an accelerated stress corrosion test modeled after the earlier Townsend studies (1975 publication). The testing is as follows: full diameter rods are installed in specially designed and fabricated test rigs that include environmental chambers used to submerge threaded parts of the rod. The applied load is increased incrementally by means of hydraulic jacks and held at each step for 48 hours up to a ma im m load of 0 85F In the e ent the rod does not fail at the ma im m applied load (0 85F ) after being held for 140 ho rs the rod is to a maximum load of 0.85Fu. In the event the rod does not fail at the maximum applied load (0.85Fu) after being held for 140 hours, the rod is pulled to fracture. Extensive post-fracture testing is performed in laboratory.

V

Small Specimen Stress Corrosion Test (Raymond Test) Using small threaded specimens, the stress corrosion cracking thresholds are established using a proven accelerated incremental step load test method for comparison with the Test IV results and for use when larger samples for Test IV are not available. Test V follows ASTM F1624/F2660 protocol that establishes a procedure to measure the susceptibility of steel to hydrogen-induced failures. It does so by measuring the threshold stress intensity factor for the onset of subcritical crack growth using standard fracture mechanics analysis on irregular-shaped specimens such as t h d d b d t l th d d d i

7 Thursday, 8/28/2014

notched round bars and actual threaded rod specimens.

VI

Small Specimen Additional Verification Testing @ Reduced Load Rates (Gorman Test) This test is to validate the stress intensity factors computed in Test V using very slow step loading rates and a sustained load test. The test includes: (1) A long term (5,000 hours) sustained tests in an environmental chamber similar to Test IV and Test V. The test will be perfomed at three sustained load levels: (a) at the threshold determined in Test V, (b) at 10% above the threshold, (c) 10% below the threshold. (2) Stepped load testing on Test V size specimens at reduced load rates (halving the threshold rate) to verify the threshold.

7

slide-8
SLIDE 8

Remainder Tests

  • Test II and Test III of the 2008 Rods
  • Test completion ~ September 2014
  • Test IV in the Dry of 2008
  • Test completion ~ September, 2014
  • Test IV Post-Fracture Analysis for the 2013 and 2008 in the dry
  • Test completion ~ October 2014
  • Test VI (Part 2) Long Term Sustained Load
  • Test completion ~ February 2015

Final Report will be issued after completion of all tests

8 Thursday, 8/28/2014

slide-9
SLIDE 9

Test II — Laboratory Mechanical & Chemical Tests

Charpy Impact Test Reduced Size Tensile Coupon Test Full-scale Test Charpy Sample Chemistry

9 Thursday, 8/28/2014

Lab Hardness

9

slide-10
SLIDE 10

Typical Test I, II, and III Results

2006 2008 2010 2013 2006 (Average) 2008 (Average) 2010 (Average) 2013 (Average) Hardness — Lab (R/2) (HRC) 35 36 34 35 (R/2) (HRC) 35 36 34 35 Hardness — Lab (Edge) (HRC) 34 38 35 36 Toughness - CVN (ft-lb) 35 14 37 48 Full Size Tensile (ksi) 159 161 153 162

10 Thursday, 8/28/2014

slide-11
SLIDE 11

Tests IV, V and VI (Tests in Salt Water)

3 5% NaCl Solution 3.5% NaCl Solution

11 Thursday, 8/28/2014 11 Thursday, 8/28/2014

slide-12
SLIDE 12

Test IV — Townsend Test Results (2010 & 2006)

12 Thursday, 8/28/2014 12 Thursday, 8/28/2014

slide-13
SLIDE 13

Test IV — Townsend Test Results

13 Thursday, 8/28/2014 13 Thursday, 8/28/2014

slide-14
SLIDE 14

Test IV — Townsend Test Results

14 Thursday, 8/28/2014 14 Thursday, 8/28/2014

slide-15
SLIDE 15

Test IV — Townsend Test Results (2008)

15 Thursday, 8/28/2014 15 Thursday, 8/28/2014

slide-16
SLIDE 16

Test V — Raymond Test Results

16 Thursday, 8/28/2014 16 Thursday, 8/28/2014

slide-17
SLIDE 17

Test VI Gorman Test Results

17 Thursday, 8/28/2014 17 Thursday, 8/28/2014

slide-18
SLIDE 18

Testing Program Main Results

  • 2008 A354BD: Rods no longer in use on the SAS
  • Test IV replicated the field results with the rods failing at 0 70Fu when
  • Test IV replicated the field results with the rods failing at 0.70Fu when

exposed to water thereby validating Test IV protocol.

  • Top and bottom segments of the bolts failed at same load level of 0.70Fu.
  • 2006/2010/2013 A354BD: Rods in service
  • In Test IV, all rods failed at 0.80Fu or greater indicating that the SCC

threshold of these rods can be conservatively set at 0 75Fu threshold of these rods can be conservatively set at 0.75Fu.

  • Test V and Test VI corroborate the threshold established in Test IV.
  • Rods with threads rolled after heat treatment exhibit superior resistance to SCC

than cut threads.

  • Rods with higher toughness (higher CVN) exhibit higher SCC threshold.
  • The threshold of both galvanized and ungalvanized 2013 rods in Test IV is at or

18 Thursday, 8/28/2014

The threshold of both galvanized and ungalvanized 2013 rods in Test IV is at or greater than 0.80Fu.

slide-19
SLIDE 19

Pier E2 2008 Rods vs. 2010 Rods

2008 (32 Failed Rods) 2010 (Rods in Service for 15+ months) No Vacuum Degassing Vacuum Degassing Double Heat Treatment Single Heat Treatment No Magnetic Particle Testing (MT) MT of threads Water removed from base of Rod several times during construction Through Bolts. No standing water issue Fabricated and Installed in 2008 I t ll d d T i d i A il 2013 / Fabricated and Installed in 2008 Tensioned in March 2013 Installed and Tensioned in April 2013 +/- After rod failure, pockets of water/air discovered in grouted Top Hat Through Bolts. No indications of grouting issues. Hardness Range: 26 39 Hardness Range: 27 38 Hardness Range: 26-39 (< HRC 39 required at R/2) Hardness Range: 27–38 (< HRC 39 required at R/2) CVN @ 40F : 13.5–18 ft.lb CVN @ 40F : 36–39 ft.lb Elongation: 12.5% to 15% (14% i i d) Elongation: 14% to 17% (14% i i d) (14% min required) (14% min required) UTS: 159–171 ksi UTS: 153–158 ksi Electrochemical potential ~ -1.01 Vsce Electrochemical potential ~ -0.92 Vsce Thread Deformation None 19 Thursday, 8/28/2014 Thread Deformation None

slide-20
SLIDE 20

A354BD Rods Capacity with Supplemental Barrier

20 Thursday, 8/28/2014 20 Thursday, 8/28/2014

slide-21
SLIDE 21

Conclusions

  • The testing program established a conservative threshold in an

aggressive salt water environment equal to 0.75Fu for the A354BD rods tl i i th SFOBB SAS currently in service on the SFOBB-SAS.

  • The pre-tension of A354BD rods on the SAS ranges from 0 10Fu to a
  • The pre tension of A354BD rods on the SAS ranges from 0.10Fu to a

maximum of 0.70Fu which is less than the threshold of 0.75Fu.

  • With supplemental barrier, the capacity of A354BD Rods will be at least

1.0Fu

  • Based on the above it is concluded that the A354BD rods in service on

the SAS are safe as they are not susceptible to SCC at the design loads and conditions.

21 Thursday, 8/28/2014

slide-22
SLIDE 22

Recommendations

  • Galvanized A354BD rods on the SFOBB-SAS shall be protected from

exposure to water with one supplemental barrier

  • dehumidification
  • paint system
  • Grout
  • Grout
  • grease caps
  • Replacement or reducing the pre-tension level of the A354BD Rods is

not necessary not necessary

  • The A354BD rods on the SAS shall be inspected and maintained per

the SAS maintenance manual.

22 Thursday, 8/28/2014

slide-23
SLIDE 23

Recommendations (Continued)

Survey of A354 BD Rods in SAS Supplemental Moisture Barrier y pp

Rod Data As- Built Protection Barrier fied ps Group ID A354 BD Bolt Location Tension (%Fu) Dehumidif Primer Grout Grease Ca Supplemental Moisture Barrier 2 Pier E2 Shear Key and Bearing Lower Anchor Rods 70

y g 3 Pier E2 Shear Key Anchor Rods — Top Housings 70

X

4 Pier E2 Bearing Anchor Rods — Top Housing 70

X

5 Pier E2 Bearing Bushing Bolts 61

6 Pier E2 Bearing Retainer Ring Bolts 40

7 PWS Strand Anchor Rods 32

8 Tower Saddle Tie Rods 68

9 Tower Saddle Turned Rods 45

10 Tower Saddle Grillage Bolts 10

11 Tower Outrigger Rods 10

11 Tower Outrigger Rods 10

12 Tower Anchorage Anchor Rods (75 Dia.) 48

13 Tower Anchorage Anchor Rods (100 Dia.) 37

14 East Saddle Anchor Rods 10

15 East Saddle Tie Rods 20

23 Thursday, 8/28/2014

16 Cable Bracket Anchor Rods 16

slide-24
SLIDE 24

Recommendations (Continued)

  • Supplemental Barrier to the E2 Upper Bearings and Shear Key Rods

shall be provided.

24 Thursday, 8/28/2014

slide-25
SLIDE 25

THANK YOU THANK YOU

25 Thursday, 8/28/2014 25 25