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 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. Sheldon W. Dean Jr., Sc.D., P.E. Robert Heidersbach, Ph.D., P.E. Thomas Langill, Ph.D. 2 Thursday, 8/28/2014
A354BD Rods at E2 — Break Locations 2008 — Location 2010 — 48 Rods of Breaks 2010 — 24 Rods March 2013 24Rods 3 Thursday, 8/28/2014
ASTM A354 Grade BD Rods Across SFOBB-SAS Thursday, 8/28/2014 4
A354 BD Galvanized Bolts Tension Item Quantity Diameter (Fraction Average Location No. Description Installed (in) of Fu) Hardness 1 2008 Shear Keys Anchor Rods – Bottom (S1/S2) 96 3 0.70 37 2 2010 Shear Keys and Bearing Rods y g 192 3 0.70 34 3 Shear Key Anchor Rods – Top 320 3 0.70 35 Pier E2 4 Pier E2 Bearing Rods – Top Housing 224 2 0.70 35 5 Spherical Bearing Bushing Assembly Bolts 96 1 0.61 36 6 6 Bearing Retainer Ring Plate Assembly Bolts Bearing Retainer Ring Plate Assembly Bolts 336 336 1 1 0 40 0.40 35 35 Anchorage 7 PWS Strand Anchor Rods (Main Cable) 274 3-1/2 0.32 35 8 Tower Saddle Tie Rods 25 4 0.68 35 9 Tower Saddle Turned Rods (@ Splices) 108 3 0.45 37 Top of Tower p 10 Tower Saddle Grillage Bolts 90 3 0.10 34 11 Tower Outrigger Rods 4 3 0.10 39 12 Tower Anchorage Anchor Rods (75 Dia. Anchor Rods) 388 3 0.48 34 Bottom of Tower 13 Tower Anchorage Anchor Rods (100 Dia. Anchor Rods) 36 4 0.37 33 14 East Saddle Anchor Rods 32 2 0.10 37 East Saddles 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 Pier E2 (New) 18 E2 2013 Replacement Rods (CCO 312) 8 3 0.70 35 5 Thursday, 8/28/2014
Testing Program Objective F rther in estigation of the fract re Further investigation of the fracture of the A354BD threaded rods. Evaluate if other A354BD threaded rods require modifications rods require modifications. 6 Thursday, 8/28/2014
Testing Program Summary TEST TEST NAME TEST PHOTO TEST PURPOSE AND DESCRIPTION NO. 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. Field Hardness Test I (in-situ) 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. 1. Laboratory hardness is performed as a verification of the field hardness measurements in Test I. Laboratory Tests: 2. Toughness (Charpy V-Notch) testing and determining the chemical composition are to characterize the material. II Hardness, Charpy, and Chemistry 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. 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- III Full Size Tension Test 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. 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). Full Diameter Rod Stress IV Corrosion Test The testing is as follows: full diameter rods are installed in specially designed and fabricated test rigs that include environmental chambers used to (Townsend Test) 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. Using small threaded specimens, the stress corrosion cracking thresholds are established using a proven accelerated incremental step load test Small Specimen Stress 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 V Corrosion Test protocol that establishes a procedure to measure the susceptibility of steel to hydrogen-induced failures. It does so by measuring the threshold (Raymond Test) stress intensity factor for the onset of subcritical crack growth using standard fracture mechanics analysis on irregular-shaped specimens such as notched round bars and actual threaded rod specimens. t h d d b d t l th d d d i Small Specimen 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: Additional Verification (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 VI Testing @ Reduced Load 7 sustained load levels: (a) at the threshold determined in Test V, (b) at 10% above the threshold, (c) 10% below the threshold. Thursday, 8/28/2014 7 Rates (2) Stepped load testing on Test V size specimens at reduced load rates (halving the threshold rate) to verify the threshold. (Gorman Test)
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
Test II — Laboratory Mechanical & Chemical Tests Charpy Impact Test Reduced Size Tensile Coupon Test Full-scale Test Chemistry Charpy Sample 9 9 Thursday, 8/28/2014 Lab Hardness
Typical Test I, II, and III Results 2006 2006 2008 2008 2010 2010 2013 2013 (Average) (Average) (Average) (Average) Hardness — Lab 35 35 36 36 34 34 35 35 (R/2) (HRC) (R/2) (HRC) Hardness — Lab 34 38 35 36 (Edge) (HRC) Toughness - CVN 35 14 37 48 (ft-lb) Full Size Tensile 159 161 153 162 (ksi) 10 Thursday, 8/28/2014
Tests IV, V and VI (Tests in Salt Water) 3 5% NaCl Solution 3.5% NaCl Solution 11 11 Thursday, 8/28/2014 Thursday, 8/28/2014
Test IV — Townsend Test Results (2010 & 2006) Thursday, 8/28/2014 Thursday, 8/28/2014 12 12
Thursday, 8/28/2014 Thursday, 8/28/2014 Test IV — Townsend Test Results 13 13
Thursday, 8/28/2014 Thursday, 8/28/2014 Test IV — Townsend Test Results 14 14
Test IV — Townsend Test Results (2008) Thursday, 8/28/2014 Thursday, 8/28/2014 15 15
Thursday, 8/28/2014 Thursday, 8/28/2014 Test V — Raymond Test Results 16 16
Thursday, 8/28/2014 Thursday, 8/28/2014 Test VI Gorman Test Results 17 17
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 The threshold of both galvanized and ungalvanized 2013 rods in Test IV is at or greater than 0.80Fu. 18 Thursday, 8/28/2014
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