Contractor Inquiry Responses, California Toll Bridge Seismic Retrofit


04-043844

CONTRACTOR'S INQUIRY RESPONSES NO. 1,

JULY 10, 1998


CALTRANS TOLL BRIDGE PROGRAM ADDRESS

The Caltrans District 4 Office is located at 111 Grand Avenue, Oakland, CA 94612. The mailing address is P.O. Box 23660, Oakland, CA 94623-0660. The Toll Bridge Duty Senior telephone number is (510) 286-5549, and the fax number for Contractor's inquiries submittals is (510) 286-4563

1) Would contract plan electronic files be available to contractor?

Contract plan electronic files will not be available to Contractors.

2) Coastwise trade determination for qualified barges.

"A non-coastwise qualified barge may be used as a moored stationary work platform within the territorial waters of the United States without violating the coastwise laws, provided that it transport neither passengers nor merchandise while under tow between coastwise points." Contractors have to get all the appropriate permits from the US Coast Guard.

3) Does the worker's compensation insurance for this project fall under the jurisdiction of the United States Longshore and Harbor Worker Act/or the Jones Act?

The Jones Act (46 U.S.C. & 13 et seq.) applies to seamen and shipping and does not relate to construction workers on the bridge. The Longshore and Harbor Workers' Compensation Act (33 U.S.C. & 901 et seq.) applies to employees engaged in maritime employment. A federal court decision of the Fourth Circuit Court of Appeals has held that a construction worker employment in building a bridge over navigable water, designed to benefit both traffic and navigation, is engaged in maritime employment under the Longshore and Harbor Workers' Compensation Act. (LeMelle v. B.F. Diamond Const. Co.)(1982) (674 Fed2.d 296). Under California law (Lab. Code & 3700), every employer is responsible for being insured against liability to pay workers' compensation. That responsibility is incorporated into the Department of Transportation's (Department) construction contracts under the provisions of the Standard Specifications Section 7-1.01(A)(6) that requires the construction contractor to certify compliance with Labor Code Section 3700.

4) Please provide a list of seismic isolation bearing manufacturers.

Lead Core/Rubber Seismic Isolation Bearings:

Dynamic Isolation Systems, Inc. 3470 Mt. Diablo Blvd., Suite A200 Lafayette, CA 94549 (510) 283-1166 Fax: (510) 283-1162

Skellerup Industries, LTD. 124 Marshall Street Private Bag 4736 Christchurch, New Zealand (011)(643) 384-0471 Fax: (011)(643) 384-0472

Viscous Dampers:

Taylor Devices, Inc. 90 Taylor Drive North Tonawanda, NY 14120 (716) 694-0800 Fax: (716) 695-6015

Enidine, Inc. Enidine West 212 Technology Drive, Suite M Irvine, CA 92718 (714) 727-9112 Fax: (714) 727-9107

5) Please refer to the last pargraph under the Section "Serpentine Material" (page 145) and the last paragraph under the section "Measurement and Payment"(page 164) of the Specifications. These sections state that the testing, handling and treatment or disposal of groundwater containing asbestos contiamination will be paid for as extra work. Will the removal and disposal of asbestos-contaminated excavated material from the CIDH piling or micropiling construction also be paid for as extra work?

No. Removal and disposal of asbestos contaminated material from CIDH piling or micropiling is full comp. under the contract unit price paid for CIDH piling or micropiling.

6) Is closing or working from the marked shoulder (shown on the drawings as approximately 12 ft. wide) of the bridge restricted i.e., can the contractor perform work from the shoulder at any time of the day?

Shoulder closure restrictions are clearly shown in the Lane Closure Charts No. 1 and 2 in Section 10-1.15, Maintaining Traffic" of the special provisions.

7) Will all the excavated material from the piers designated as type "AH" and "DH" on plan sheet 609/663 be considered hazardous and contaminated irrespective of the actual contaminated levels?

Attention is directed to Section 5-1.44, "Contaminated and Hazardous Material, General" subsection "Sampling and Analysis" of the special provisions.

8) Will excavation for the Rock Slope Protection shown on plan sheets 8 & 9/663 be considered derdging? Will it come under the quantity limitations of Section 10-1.28A, paragraph 5 of the special provisions? Will it come under the requirements of the EXCAVATION, PILE, AND COFFERDAM DISCHAGES in Section 10-1.05 of the special provisions? Will it be considered hazardous and contaminated irrespective of the actual contaminated levels?

Excavation for the rock slope protection shown on sheets 8 & 9/663 is not considered dredging and is therefore not included in the dredging quantity limits stipulated in Section 10-1.28A, "Dredging" of the special provisions. All work must conform to Section 10-1.05, "Non-Storm Water Discharges" of the special provisions. Attention is directed to Section 5-1.44, "Contaminated and Hazardous Material, General" subsection "Sampling and Analysis" of the special provisions.

9) Our company has approved generalized working drawings for altternative micropiling. Caltrans did not include us on the list of approved vendors shown on page 163 of the specifications for this project. Please revise this specification section to include our company and issue this revisions in an addendum. We were included in the list of approved vendors in the alternative micropile specification for the other project out for bid on this bridge (04-043824).

See future new combined contract for Richmond-San Rafael Bridge.

10) What are the allowable construction loads that can be placed on top of the existing piers?

Per Special Provisions 10-1.26N, the Contractor shall provide full design evaluations of the shaft and foundations in terms of load carrying capacity of the elements to which the temporary supports are being anchored, and the lateral stability to the overall column.

11) What are the allowable construction loads that can be placed on the existing spandrels?

See previews response.

12) Page 78. Special Provisions, Order of Work.

a) When can the erection of precast concrete pile cap shells of the eastbound concrete trestle from bents e.g. through 37 commence?

See future new combined contract for Richmond-San Rafael Bridge.

b) Has the precast concrete pile cap shell been designed to be completely filled with concrete in one pour?

The precast concrete pile cap shell has been designed to be completely filled with concrete in one pour. The flexure and shear design of the precast concrete pile cap shell was performed using a simply supported span between centerlines of the CIDH piles. Attention is called to Note 3 on Sheet 70 of 489 in the plans. The punching shear behavior of the pile cap shell is a function of the means and methods employed by the contractor to temporarily support the pile cap shell. The design assumed a reasonable distribution of the load so that punching shear was not a critical load case.

13) Please reference, Drawing No. 485 - Main Spans, Typical Lacing Replacement Sequence 1 and Drawing No. 487 - Main Spans, Typical Perforated Plate Replacement Sequence 1. Cross Section B-B shows temporary struts composed of 3/4" HS threaded rod thru 1" diameter X-strong pipe. This procedure creates as much work to install and remove the temporary struts as is required to replace the lacing! Can the contractor design and use an alternate method other than those temporary struts when retrofitting these members?

Bid what is shown on the contract plans. Alternative construction methods will be considered by the Engineer after the bid opening. Alternative construction methods are subject to the approval of the Engineer.

14a) For Precast Jackets at Piers 62-77R, Sheets 328-332. What are the vertical HS Bar coupling details at the bottom and top terminus as well as the intermediate splice?

For vertical HS bar bottom terminus, see "Detail 7" on "Shaft Retrofit Details No. 6" sheet. Place centerline of anchor plate 1'-6" from bottom of precast surface. For vertical HS bar top terminus, see "Detail 6" on "Shaft Retrofit Dtails No. 6" sheet.

b) Additionally, what is Detail 11 on sheet 332 to be applied as these are 7/8" bars?

See future new combined contract for Richmond-San Rafael Bridge.

15) Closure Pours -Page 110 of the plans show the "high early strength" concrete to be at 4000 psi before traffic can go on the 4-span frame. It is our interpretation that we can pour three closures and place steel plates over the joints to allow daytime traffic to go on until 4000 psi is achieved and then the plates can be removed. So the following sequence will be followed:

  • Place four girder sections. Deck closure required.
  • Pull strand. Deck closure required.
  • Shim girders and stress 25%. Deck closure required.
  • Pour three closure pours and plate joints. Deck closure required.
  • When 2500 psi is achieved, stress 4-span frame. Deck closure required.
  • When 4000 psi is achieved, removed plates. Deck closure required.
  • Please confirm that this is the correct interpretation.

    This is not a correct interpretation of the plans and specifications. The three closure joints must be poured, reach a minimum strength of 4000 psi, and the continuity post-tensioning stressed in one construction phase. No live load is to be placed on bridges with closure joints that are not prestressed. See plan sheet 110 of 489 and SP 10-1.38 page 177.

    16) On the above referenced sheet, the detail for the upper level transverse bumper bracket detail states that it is typical for all piers except for piers 67, 68 & 69. On sheets 352 & 353 the details shown are for piers 6, 9, 10, 13, 14, 15 & 16. Are these for the upper level transverse bumper brackets as well? Should the note on sheet 351 exclude piers 6, 9, 10, 14, 15 & 16 as well as piers 67, 68 & 69? If not, which detail is correct? A table may help the contractor to determine which detail applies to which pier.

    Upper Level Transverse Bumper Bracket Detail shown on sheet 351 of 663 apply to all piers except for details shown on "Bumper Bracket Details No. 2 through No. 5" sheets (Plan sheet 351 thru 355 of 663).

    17) On plan sheets 65 and 66 where the "bottom of footing elevation" symbols are provided, do these elevations represent the elevations of the bottom of the existing footing concrete or the bottom of the existing seal course concrete?

    Per Plan sheet 224 & 225 of 663, bottom of footing (not seal course) elevations are indicated.

    18) The Contract Plans and Specifications detail a precast shell at bent caps 1-37. This construction detail poses several problems. In order to save the state money and reduce the bids we are requesting that a traditional bent cap design be allowed. If not, we are curious to know if the bent cap precast shell and the main bent cap can be cast in place at the same time. We foresee several problems with the precast shell design.

    a) The precast shell can not be placed without removing the existing bridge span if the CIDH pile has been completed. The rebar that extends above the pile will not allow the placement of the shell. Therefore, the contractor would be required to remove and replace, with temporary bridge spans, large sections of the existing bridge so that the project could be cycled within a timely period. This operation would be very costly and timely.

    b) The other alternate would be to place the precast shell prior to the placement and completion of the pile. Using this alternate is also undesirable. The precast shell would be exposed (during) the CIDH operation. The shell would be easily damaged. Therefore, the shell would require extensive repair and cleaning prior to completing the bent cap.

    c) The precast shell also poses the problem of rigging an additional sixty ton pick. Then the contractor has to rig the shell so that it maintains its location until the pile can support it.

    The precast shell can be placed without removing the existing bridge. Refer to plan sheets 42 and 47 of 489 for the sequence of construction. The shell is placed after the concrete has been placed in the steel shell of the CIDH up to the level of the construction joint shown in the plans, and has reached a strength sufficient to support the precast shell. Also refer to pages 153 and 154 of the special provisions. Bid the precast shell as shown.

    19) The existing piers have an existing black coating which has been painted on. What is this coating, and is it to be removed for underwater grouting?

    If the existing coating can not be readily removed with wire brush and is adequately bonded to the existing concrete, it does not need to be removed.

    20) The second to the last paragraph on page 183 of the Special Provisions Section 10-1.41, "Precast Concrete Panels," refers to the core drilling and core grouting for the precast panels. According to the paragraph, payment for the cores and grouting is to be paid for in the erect precast item 66(s). This work is also covered on page 188, Section 10-1.46, "Core and Pressure Grout (11/2 ", 2", 3", 4")." According to this section, payment for coring and grouting the 3 inch cores is to be made under this Bid Item - 72(s). We assume that Bid Item 72(s) is the correct one. Please advise if this is correct.

    Special Provisions Section 10-1.41 payment clause is for core holes related to installation of precast concrete panels. Special Provisions Section 10-1.46 payment clause is for core holes not related to installation of precast panels.

    21) The Specifications for the installation of the stud connectors refer to the specs for Core Concrete (2",5"). Per Detail 4 on Sheet 401 of 663, the plans call for a 3" hole to be filled with a rapid setting concrete patch. It appears as though there is no item to pay for this 3" coring.

    Per Special Provisions Section 10-1.60 on page 227, installing stud connectors is included in the contract price paid per pound for erect structural steel (bridge). Special Provisions Section 1-1.61 first paragraph states "Installing stud connectors shall consist of coring through reinforced concrete deck,... and filling cored holes with rapid setting concrete patches..."

    22) Is there a seal course at Pier 74R? If so, what is the thickness? Plan Sheet 310 of 663, Section D-D shows no seal course, while Plan Sheet 311 of 633, Section C-C showns a 2'-0" thick seal course.

    Per Plan Sheet 310 of 663, Pier 74R has a 6'-0" thick footing and no seal course. Pier 74R footing and seal course thickness at "Section C-C" on Plan Sheet 311 of 663 to be neglected.

    23) Sheet 350-Column Casing Data Table there is no "L2" Dimension for pier 77, yet Sheet 421 indicates that this dimension would be 2.5' for piers 72-77. Is this correct?

    Per Plan Sheet 421 of 663, Pier 77 3/4" thick casing is 2'-8" long. Consequently, L2 dimension for Pier 77 on Plan Sheet 350 of 663 is 2'-6".

    24) Reference Sheets 396 & 399 of 663, Relocation of Existing Maintenance Rail. Are the maintenance rails only supported at the floorbeams above the piers on the girder spans? If not, what do the intermediate supports look like and how many are there? What will their new connection look like?

    For Pier 62 through pier 77R, existing maintenance rails are supported at the floor beams above the piers with the details shown on Plan Sheet 399 of 663. Rails between floor beams above the piers are supported by existing 22 or 24 Type "A" hangers. These hangers do not need to be replaced.

    25) Subject: Bridge removal, reference sheet 451 of 489, Spec section 10-1.26H bridge removal, "Location B". Is "bridge removal (portion)" as shown on sheet 451, removal of seal concrete, being a part of the existing pier concrete, measured and paid under Bid Item 36 "Bridge removal (portion), Location B"?

    Removal of seal course, as shown on Plan Sheet 610 of 663, is measured and paid under Bid Item 38, Bridge Removal (Portion), Location E.

    26) Please review entire weld assembly of stiffeners to column casing pp 404-424. Many errors exist. A few examples below.

    a) Page 407 & 410 of 663, Section A-A, shows shop weld of 1" Cover Plate to Bumper Bracket 1/2" Top Plate to Bumper Bracket 1/2" vertical skirt. How is the field weld of the 1" Cover Plate to column casing to occur?

    b) Page 407 of 663, section A-A. Why is the 1" Vertical Bracket shown with shop CIP from one side and the Stiffener Plates are field welded?

    c) Page 409 of 663, plan view. Why is 1" x 3-1/2" plate shown one piece if it is divided through section B-B?

    d) Page 412 of 663, section B-B, no weld symbol for Lower Stiffener Cover Plate?

    e) Page 413 of 663, plan view, shows shop weld of cover plate to Stiffener Cover Plate to Stiffener to Column Casing which ties all three together, yet the Column Casing is field welded to the Cover Plate, impossible?

    f) Page 415 of 663, plan view, shows Steel Casing joint though narrow radius of ellipse yet it shows 1" plate continuous without welds.

    g) Page 407 of 663, section A-A & Detail A, width of Vertical Bracket Plate shown 14"x1"x1'-6" in section A-A and 15-1/2"x1"x1'-6" in detail A. Which is correct?

    h) Why are all the stiffeners classified as column casings when they should be structural steel, bridge?

    i) ETC.

    See future new combined contract for Richmond-San Rafael Bridge.

    27) Please reference the 1/2" and 1" HS Threaded Rods on Drawing 229/663. Are the rods required to be coated? If so, with what? Under which bid item are the HS Threaded Rods paid? The 1/2" and 1" Threaded Pigtail Inserts are specified to have 9,000 lb and 37,500 lb safe working loads respectively. Based on manufacturer's data, these working loads cannot be obtained in a 7-1/2' thick concrete wall. Please resolve this conflict. Are the inserts required to be coated? If so, with what?

    See future new combined contract for Richmond-San Rafael Bridge.

    28) Please reference Specification 10-1.31 TEST BORINGS which states "For cast-in-drilled hole concrete piling, continuous rock cores shall be made from the specified bottom of steel casing elevation down to 25 feet below the specified bottom of steel casing elevation." At which cast-in-drilled hole concrete piles are the test borings required?

    See future new combined contract for Richmond-San Rafael Bridge.

    29) Please reference drawing 226, 227 & 235 /663 CAST-IN-DRILLED HOLE CONCRETE PILE. There is a dimensional conflict in the information provided to determine the depth to center line of the rebar no splice zone below the construction joint. As an example please review the following calculations for pile 32-R.
    Pile cutoff elevation 3.08
    Bottom of steel casing -69.50
    Length of steel casing 72.58
    Dimension of bottom of steel casing to center line of no splice zone 12.50
    Calculated depth to center line of no splice zone 60.08
    Depth to center line of no splice zone from pile data table 69.00
    Difference 8.92
    Please resolve this conflict.

    The bottom of the "No Splice Zone" does not correspond with the bottom of steel casing. The depth to centerline of "No Splice Zone" shown in the Pile Data tables is correct.

    30) Will a vibratory pile hammer be allowed for driving piles for temporary construction facilities such as falsework or work trestles?

    Vibratory hammers will not be allowed for driving any piles or casing on the project.

    31) It will be necessary to install temporary work platforms or work trestles between the existing eastbound and westbound west approach trestles. Can these platforms or trestles be supported off of the existing bridge deck or pile caps? If so, are there any restrictions?

    Although the details shown on the plans do not specifically require temporary work platforms between the existing trestles, such platforms could be used and could be supported off the existing bridge deck or pile caps. However, the Contractor must submit working drawings and design calculations for such platforms to the Engineer for approval. The work platforms and the loads they carry shall not adversely effect the existing trestle structures.

    32) Please reference Specification 10-1.03 ORDER OF WORK which states "The Stage 1 construction of the eastbound Concrete Trestle, as shown on the contract plans, from Station 277+96.815 to Station 286+33.209 on the "L" Line, shall be a first order of work. The work shall begin from the east end and proceed toward the west. Erection of precast concrete cap shells of the eastbound concrete trestle from Bents 29 through 37 shall not begin until the foundation retrofit work at Piers A through 8 from Contract No. 04-043824 has been complete." There are no schedule restrictions placed on the 04-043824 contract for this phase of the work. This may place unrealistic schedule constraints on the 04-043844 contract depending on when the 04-043824 accomplishes this work. Please resolve this conflict between the two contracts.

    See future new combined contract for Richmond-San Rafael Bridge.

    33) Please reference drawing 235/663 CAST-IN-DRILLED HOLE CONCRETE PILE ELEVATION. Piles 33-L through 37-L are installed under low overhead conditions. The restrictions on pile reinforcing steel splice zones and extensions above the construction joint are in conflict with low overhead conditions. The reinforcing steel cannot be instatlled. Please resolve this conflict.

    The overhead clearance restrictions for CIDH piles 33-L thru 37-L have been reviewed and no conflicts were found to prohibit the installation of the pile reinforcing. The details shown on the plans indicate areas of the CIDH piles where splices are not allowed and a required splice at the construction joint. Neither the plans nor specifications disallow the use of lap splices or butt splices outside these areas in order to place the reinforcting under low overhead conditions.

    34) Ref. Project Plan Sheet 350, "Column Retrofit Details No. 16"; Please provide "L2" dimension for Pier 77.

    See future new combined contract for Richmond-San Rafael Bridge.

    35) Ref. Project Plans Sheet 351, "Upper Level Longitudinal Bumper Bracket Detail": Note indicates this detail occurs at Piers 72 thru 78 both columns and Pier 71 left column. Project Plan Sheets 371 and 372 indicate additional brackets at Piers A thru 7 and 11. Please advise if brackets are reuqired at Piers A thru 7 and 11.

    See future new combined contract for Richmond-San Rafael Bridge.

    36) Ref. Project Plan Sheet 404, "Stepped Casing Shear Key Detail": Can the 1-1/2" x 10" x 0'-11-1/4" plates be welded to the 1" cover plate in the fabrication shop?

    See future new combined contract for Richmond-San Rafael Bridge.

    37) Ref. Project Plan Sheet 405, "Bumper Box Detail": Can the bumper boxes be welded to the column casing in the fabrication shop?

    See future new combined contract for Richmond-San Rafael Bridge.

    38) Ref. Project Plan Sheet 406: The vertical restrainer rods must be installed prior to erecting the 1" column casing/cover plate. Once rods are installed, the cover plate can't be erected over the rods as the rods pass through the girder flange above. (Same as sheet 408.) Please advise.

    See future new combined contract for Richmond-San Rafael Bridge.

    39) Fluid Level Indicator. Section 10.1.54, page 205 of the Specifications states that the damping devices shall include a "permanent in-place fluid level indicator." To maintain the highest quality possible, avoiding additional appendages on fluid dampers is necessary. This type of indicator not only indicates that a device requires fluid replenishment but it also introduces a potential leak path by requiring an additional hole in the fluid containment cylinder. The industry standard has been to use a detachable pressure gauge to monitor the damper fluid level during routine inspection. This type of device is very similar to checking the air pressure in car tires. Is a removable fluid level indicator acceptable?

    Alternate construction methods for the indicator will be considered by the Engineer after the bid opening. Alternative construction methods are subject to the approval of the Engineer.

    40) Section 10.1.54, page 205 of the Specifications states that the dampers "shall be designed to withstand the fuse force (Ffuse) within the maximum allowable fuse displacement (dfuse)". The fuse displacement will be directly dependent on the fluid column length in the damper. Therefore, we would like to know the stroke position for the fuse to be activated. DO THE FUSE DISPLACEMENT REQUIREMENTS ONLY APPLY AT THE MID-STROKE POSITION OR DO THESE REQUIREMENTS APPLY AT ALL STROKE POSITIONS?

    The fuse displacement requirements apply at all stroke positions.

    41) Prototype Tests. Section 10.1.54, page 207 of the Specifications states "Prototype Test 3, Ten fully reversed cycles of constant-velocity loading at 1.2 times the design velocity to .25 times the design maximum displacement shown on the plans. In the event of test facility limitations, the test shall be performed for ten one-half cycles separately in compression and tension of the damping device, where one-half cycle is defined as follows: from zero displacement to 0.25 times the design maximum displacement and back to zero displacement." This translates to a velocity of 130 in/sec with a stroke of 18.5 inches. To the best of our knowledge, there is no test lab that exists that can perform this test with a hydraulic test rig. Is it acceptable to use heavy weight hammer drop testing for tests that are beyond the velocity capabilities of functional test labs?

    See future new combined contract for Richmond-San Rafael Bridge.

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    Caltrans Toll Bridge Program always welcome any comments or suggestions.
    Author:Yader A. Bermudez
    Email: Bernie_Edrada@dot.ca.gov