BID SPECS - Attachment 2.pdf

PDF 1 MB Posted Jun 27, 2025

Attached to: Weld County Human Services Building B HVAC Upgrade
Solicitation number: B2500092
Issued by: Weld County, Colorado

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Written by GovTribe AI · Jun 27, 2025

This document is a structural engineering analysis prepared by EV Studio for Weld County Facilities Department regarding HVAC upgrades at the Weld County Human Resources Building B located at 315 N 11th Avenue in Greeley, Colorado. The report focuses on analyzing the structural support requirements for six new rooftop units (RTUs) being installed, specifically examining whether the existing open-web roof joists can support the new equipment without requiring primary reinforcement. The analysis is based on existing architectural drawings from 1997 and 2009, and mechanical cut sheets from TRANE, with the proposed plan involving positioning new units in the same locations as existing units using curb adapters.

The structural analysis determined that for all six RTUs (RTU-01 through RTU-06), no primary joist reinforcement is needed, provided the units are installed as planned and existing conditions match the architectural drawings. The total weights of the new units, including existing and new curb adapters, range from 1,561 lbs to 2,909 lbs. The report emphasizes that the General Contractor must field verify existing conditions and notify EV Studio if any variations are discovered, as changes could necessitate additional structural reinforcement. The analysis follows guidelines from the 2018 International Existing Building Code and includes detailed diagrams showing proposed support methods, angle reinforcements, and potential web member reinforcement techniques.

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Bid Specs - Human Services Building B HVAC Upgrade - 92.docx	DOCX document	Jun 27, 2025
BID SPECS - Attachment 1.pdf	PDF	Jun 27, 2025

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5335 W. 48th Avenue, Ste #300 303.670.7242 ph design@evstudio.com Denver, Colorado 80212 303.679.1862 fax www.evstudio.com

March 31, 2025

Will Hopkins, Project Manager Weld County Facilities Department whopkins@weldgov.com (970)400-2044 1105 H Street P.O. Box 758 Greeley, CO 80632

Re: Weld County Human Resources Bldg B HVAC Upgrades 315 N 11th Ave Greeley, CO 80631

Re: Structural Support for New Rooftop Units

Dear Will, We have analyzed the replacement of the proposed rooftop units (RTU) to determine the conditions for which new reinforcement will be needed for the supporting open-web roof joists.

Mechanical designs propose that the new RTUs be located in the same locations as the existing through the use of curb adapters attached to the existing mechanical unit curbs. Based on this assumption our analysis shows the weights of the new RTUs to be acceptable without new primary reinforcing of the existing open-web joists at all locations.

Our analysis is based on existing drawings dated 8/25/1997 from Bley Associates Architects Planners, remodel drawings dated 9/10/2009 from Hauser Architects, P.C., and from the mechanical cut sheets for the RTUs provided by TRANE. If the structural configuration or existing locations of the mechanical units are found to be different from the existing structural drawings (Roof Framing Plan, Sheet S3, Bley Associates Architects Planners, 8/25/1997) please notify EV studio.

While we have found that with the use of curb adapters at the expected RTU locations, that no new primary joist reinforcement is needed, other structural reinforcing may still be needed.

Primary reinforcing consists of reinforcing the individual elements of the joists and their connections to each other. If primary reinforcing is required, typically it would be needed for the web members of the open-web joist. Detail 4 shows this structural reinforcing of web members. In the infrequent instance that the bottom chord would need reinforcing, that would consist of a steel plate welded to the bottom chord as described in Detail 4. While our current calculations show neither type of primary reinforcement is needed, it may still be required if it is determined that curb adapters are not feasible or if the existing RTU locations are different from the existing structural drawings. Other more typical structural reinforcements may also still be required if the existing reinforcements are found to be missing or inadequate. Angle supports at unsupported edges of the units and at the roof deck openings are required. If these cannot be field verified, then they shall be installed per Detail 1 and Detail 2. Also, typical open-web joist reinforcement at point loads away from existing panel points is required per Detail 3 if it cannot be field verified.

The GC shall field verify the existing conditions and notify EVstudio.

Our analysis shows that the bar joists supporting RTU-01 do not need primary structural reinforcement. This unit is to be located at the same location as the existing unit near grid intersection (5, D) using a curb adapter fitted to the existing curb. The expected total weight of this unit including the existing curb and new curb adapter is 1,895 lb. It is expected that the new corner loads of the unit will not exceed 477 lb on each of the 2 supporting joists. Our analysis shows that the load effects to the supporting bar joist structural elements and connections are not

2/13

Denver, Colorado 80212 303.679.1862 fax www.evstudio.com increased by more than 5% as allowed by the 2018 International Existing Building Code, so primary reinforcement to the bar joists is not required.

Our analysis shows that the bar joists supporting RTU-02 do not need primary structural reinforcement. This unit is to be located at the same location as the existing unit near grid intersection (2, D) using a curb adapter fitted to the existing curb. The expected total weight of this unit including the existing curb and new curb adapter is 1,561 lb. It is expected that the new corner loads of the unit will not exceed 477 lb on each of the 2 supporting joists. Our analysis shows that the load effects to the supporting bar joist structural elements and connections are not increased by more than 5% as allowed by the 2018 International Existing Building Code, so primary reinforcement to the bar joists is not required.

Our analysis shows that the bar joists supporting RTU-03 do not need primary structural reinforcement. This unit is to be located at the same location as the existing unit near grid intersection (2, B) using a curb adapter fitted to the existing curb. The expected total weight of this unit including the existing curb and new curb adapter is 1,568 lb. It is expected that the new corner loads of the unit will not exceed 477 lb on each of the 2 supporting joists. Our analysis shows that the load effects to the supporting bar joist structural elements and connections are not increased by more than 5% as allowed by the 2018 International Existing Building Code, so primary reinforcement to the bar joists is not required.

Our analysis shows that the bar joists supporting RTU-04 do not need primary structural reinforcement. This unit is to be located at the same location as the existing unit near grid intersection (5, B) using a curb adapter fitted to the existing curb. The expected total weight of this unit including the existing curb and new curb adapter is 1,895 lb. It is expected that the new corner loads of the unit will not exceed 477 lb on each of the 2 supporting joists. Our analysis shows that the load effects to the supporting bar joist structural elements and connections are not increased by more than 5% as allowed by the 2018 International Existing Building Code, so primary reinforcement to the bar joists is not required.

Our analysis shows that the bar joists supporting RTU-05 do not need primary structural reinforcement. This unit is to be located at the same location as the existing unit near grid intersection (4, D) using a curb adapter fitted to the existing curb. The expected total weight of this unit including the existing curb and new curb adapter is 2,820 lb. It is expected that the new corner loads of the unit will not exceed 905 lb on each of the 3 supporting joists. Our analysis shows that the load effects to the supporting bar joist structural elements and connections are not increased by more than 5% as allowed by the 2018 International Existing Building Code, so primary reinforcement to the bar joists is not required.

Our analysis shows that the bar joists supporting RTU-06 do not need primary structural reinforcement. This unit is to be located at the same location as the existing unit near grid intersection (4, B) using a curb adapter fitted to the existing curb. The expected total weight of this unit including the existing curb and new curb adapter is 2,909 lb. It is expected that the new corner loads of the unit will not exceed 933 lb on each of the 3 supporting joists. Our analysis shows that the load effects to the supporting bar joist structural elements and connections are not increased by more than 5% as allowed by the 2018 International Existing Building Code, so primary reinforcement to the bar joists is not required.

According to our analysis, the new rooftop units may be supported by the existing structure provided the locations and weights are as expected, and the proper typical angle supports are currently installed. With this proposed plan, primary reinforcing of the joists is not expected.

However, if conditions are different than expected, we will have to be notified to recheck our calculations, and primary reinforcing per Detail 4 may be required. At all units, existing angle supports at unsupported unit edges and openings (Detail 1 and Detail 2), and existing panel point reinforcement (Detail 3) must be field verified.

3/13

Sincerely, 03/31/2025

Katelyn Wager, PE, Structural Engineer, Associate Principal Date:

EV Studio, LLC 5335 W. 48th Ave. #300 Denver, CO 80212 303-670-7242 x62 katelyn@evstudio.com

03/31/2025

4/13

RTU-01 LOCATION

RTU-01

Position unit onto (E) curb with (N) curb adapter

MAX WEIGHT INCLUDING

(E) CURB AND (N) CURB

ADAPTER = 1895 LB

5/13

RTU-02 LOCATION

RTU-02

Position unit onto (E) curb with (N) curb adapter

MAX WEIGHT INCLUDING

(E) CURB AND (N) CURB

ADAPTER = 1561 LB

6/13

RTU-03 LOCATION

RTU-03 Position unit onto (E) curb with (N) curb adapter

MAX WEIGHT INCLUDING

(E) CURB AND (N) CURB

ADAPTER = 1568 LB

7/13

RTU-04 LOCATION

RTU-04

Position unit onto (E) curb with (N) curb adapter

MAX WEIGHT INCLUDING

(E) CURB AND (N) CURB

ADAPTER = 1895 LB

8/13

RTU-05 LOCATION

RTU-05

Position unit onto (E) curb with (N) curb adapter

MAX WEIGHT INCLUDING

(E) CURB AND (N) CURB

ADAPTER = 2820 LB

9/13

RTU-06 LOCATION

RTU-06

Position unit onto (E) curb with (N) curb adapter

MAX WEIGHT INCLUDING

(E) CURB AND (N) CURB

ADAPTER = 2909 LB

10/13

SECTION A

CONT. L6"X1'-0"X16 GA.

METAL DECK . RE: PLAN FOR ORIENTATION

#10 TEK SCREWS AT 6" O.C.

-TYPICAL AS SHOWN

S T

E E

L J

S T

E E

L J

L5X3X3/8 (LLV)

L X

L L V

L X

L L V

L5X3X3/8 (LLV)

RTU ABOVE

L3X3X1/4

MECH CURB

RE: 3/S720

S T

E E

L J

S T

E E

L J

L5X3X3/8 (LLV)

L X

L L V

L X

L L V

L5X3X3/8 (LLV)

RTU ABOVE

L3X3X1/4

RE: 3/S720

L5X3X3/8 (LLV)

L X

L L V

L X

L L V

L X

L L V

L3X3X1/4

NOTES:

1.)PROVIDE DECK ATTACHMENT TO ALL ANGLE FRAMING

2.) PROVIDE 2X FIRE TREATED BLOCKING OR STEEL

SHIMS UNDER HIGH FLUTES AT CURB ATTACHMENT

1 NEW ROOF TOP UNIT ANGLE

SUPPORT

11/13

SECTION A SECTION B

3/16

CONT. L6"X1'-0"X16 GA.

(4 SIDES)

IF DECK CAN BE CONNECTED DIRECTLY TO ANGLE

FRAMING, 16 GA PL CAN BE OMMITED

METAL DECK . RE: PLAN FOR ORIENTATION

#10 TEK SCREWS AT 6" O.C.

-TYPICAL AS SHOWN

SECTION C

L6X4X3/8X0'-4" LLV

STEEL JOIST/BM RE:

PLAN

3/16 1

TYP.

S T

E E

L J

S T

E E

L J

L5X3X3/8 (LLV)

L X

L L V

B A

3/16

3" MAX

AT JOIST PROVIDE

WEB REINFORCING

PER 1/S705 AT ALL

RTUS

OPTION 1 OPTION 2

STEEL JOIST/BM RE:

PLAN

3/16

AT JOIST PROVIDE

WEB REINFORCING

PER 1/S705 AT ALL

RTUS

COPE ANGLE AND

WELD TO JOIST

CHORD OR BM

"D"

ACCEPTABLE TO

OMIT ANGLE WHEN

"D" LESS THAN OR

EQUAL TO 6"

"D"

L X

L L V

L5X3X3/8 (LLV)

PROVIDE DECK

ATTACHMENT TO

ALL ANGLES

NOTES:

1.)PROVIDE DECK ATTACHMENT TO ALL ANGLE FRAMING

2 TYPCIAL ROOF DECK OPENING

12/13

3 SUPPORT FOR NEW POINT

LOADS AT BAR JOISTS

L O

A D

PANEL POINT

L O

A D A

PANEL POINT

FIELD INSTALL L2x2x1/4" EA. SIDE AS

SHOWN WHERE DIMENSION "A" IS

EQUAL TO OR GREATER THAN 4"

OWJ, TYP.; SEE ROOF FRAMING

PLAN FOR SIZE AND SLOPE

PIPE OR DUCT FOR MECH., ELEC., OR

OTHER ITEMS SHOWN ON PLANS AS

SUPPORTED BY JOIST

'U' BOLT HANGERS TYP., DO NOT WELD

ANY HANGER TO BOTTOM CHORD.

3/16" 2"

TYP.

13/13

CUT ENDS OF ANGLES TO AVOID

CONFLICTS, MAINTAIN MINMIMUM 2" WELD

LENGTH TOTAL FOR EACH ANGLE, NOTIFY

EVSTUDIO IF THERE IS TOO MUCH

CONGESTION TO MEET THIS

REQUIREMENT, GC TO HOLD

CONTINGENCY FOR 1/2" THICK X 6" WIDE X

8'-0" LONG MAX STEEL PLATE BOTTOM

CHORD REINFORCING.

EXISTING OPEN WEB JOIST

1. WHILE THE PRIMARY REINFORCING SHOWN IN THIS DETAIL IS NOT

CURRENTLY REQUIRED PER THE PROPOSED PLANS, THE GC SHALL

FIELD VERIFY (E) CONDITIONS AND NOTIFY EVSTUDIO. IF CONDITIONS

VARY FROM THE EXPECTED AS DESCRIBED IN THE NARRITIVE,

EVSTUDIO WILL NEED TO RECHECK CALCULATIONS TO SEE IF

PRIMARY REINFORCING IS REQUIRED. GC TO HOLD CONTINGENCY

FOR PRIMARY REINFORCING.

A. IF REQUIRED, GC TO FIELD VERIFY WEB CONFIGURATIONS

AND NOTIFY EVSTUDIO. PRIOR TO ANY STEEL FABRICATION,

CONFIRM THE PROPOSED STEEL REINFORCING MAY BE

INSTALLED AS DETAILED.

REINFORCE ALL WEB MEMBERS

TBD IF REQUIRED, MIN DISTANCE

DOUBLE ANGLE

REINFORCING AT DIAGONALS

BAR REINFORCING AT

VERICALS

CRIMPED ANGLE

WEB MEMBERS

FIELD INSTALL (2) L2x2x1/4 (1 EA SIDE)

AT DESIGNATED DIAGONAL WEB

MEMBERS

OWJ, TYP.; SEE ROOF FRAMING

PLAN FOR SIZE AND SLOPE

3/16"

TYP

FIELD INSTALL (2) #3 A706 WELDABLE

REBAR (1 EA SIDE) AT DESIGNATED

VERTICAL WEB MEMBERS

OWJ, TYP.; SEE ROOF FRAMING

PLAN FOR SIZE AND SLOPE

TYP

B B

VIEW B-B

REINFORCING AT

VERTICAL WEBS

REINFORCING AT

DIAGONAL WEBS

EXISTING

VERTICAL WEB

BAR REINF EA

SIDE

CHORD ANGLES

VIEW A-A

EXISTING

VERTICAL WEB

ANGLE REINF EA

SIDE

CHORD ANGLES

4 BAR JOIST PRIMARY STRUCTURAL

REINFORCEMENT

File details come from the government source that posted it. Updated Jun 27, 2025.