Content Comparison

The bridge model adapted from Federal Highway Administration Design Example 3: Three-Span Continuous Horizontally Curved Composite Steel I-Girder Bridge, Publication No. FHWA-HIF-16-002 - Vol. 23.

Design Parameters

• Structural Steel: AASHTO M270, Grade 50 (ASTM A709, Grade 50) steel with Fy = 50 ksi, Fu = 65 ksi

• Concrete: fc′ = 4.0 ksi,  = 150 pcf

• Slab Reinforcing Steel: AASHTO M31, Grade 60 (ASTM A615, Grade 60) with Fy = 60 ksi

The bridge has spans of 160.0 feet – 210.0 feet – 160.0 feet measured along the centerline of the bridge. Span lengths are arranged to give similar positive dead load moments in the end and center spans. The radius of the bridge is 700 feet at the centerline of the bridge. The out-to-out deck width is 40.5 feet, and there are three 12-foot traffic lanes. All supports are radial with respect to the bridge centerline. There are four I-girders in the cross-section. The total deck thickness is 9.5 inches, with an assumed 0.5- inch integral wearing surface. Therefore, the concrete deck’s structural thickness is 9.0 inches. The deck haunch thickness is taken as 4.0 inches and is measured from the top of the web to the bottom of the deck. That is, the top flange thickness is included in the haunch. The roadway is superelevated 5 percent. The girders in this example are composite throughout the entire span, including regions of negative flexure since shear connectors are provided along the whole length of each girder. The bridge cross-section in this design example consists of four I-girders that are spaced at 11 feet in the center with 3.75-foot deck overhangs.

Design Loads

Permanent steel stay-in-place deck forms are used between the girders; the forms are assumed to weigh 15.0 psf since it is assumed concrete will be in the flutes of the deck forms. An allowance for a future wearing surface of 30.0 psf is incorporated in this design example. The bridge is designed for HL93 live load per Article 3.6.1.2. Live load for fatigue is taken as defined in Article 3.6.1.4. The bridge is designed for 75-year fatigue life, and single-lane average daily truck traffic (ADTTSL) in one direction is assumed to be 1,000 trucks per day. The bridge site is assumed to be in Seismic Zone 1, so seismic effects are not considered in this design example. Steel erection is not explicitly examined in this example, but the sequential placement of the concrete deck is considered. The concrete is the first cast from the left abutment to the dead load inflection point in Span 1, the concrete between dead load inflection points in Span 2, and the concrete beyond the dead load inflection point to the abutment in Span 3. Finally, the concrete between the points of dead load contra flexure over the two piers is cast.

Modeling on OpenBrIM.App

	Follow the below instructions to create a Steel I Girder Bridge Workflow.
1	Click New from the left side bar
2	Click Steel Girder Bridge Workflow template
3	Click Steel I Girder Bridge Workflow to create a new project
4	Enter the project name and the category

Bridge Layout

You can define the bridge layout without modeling the actual 3D of the project through the Bridge Geometry tab on the workflow.

	Follow the below steps to create the alignment where the bridge will be located.
1	Go to Roadway Alignment
2	Enter Start Station as 0
3	Click the three-dots icon on the cell and Click Editor to define alignment properties
4	Click + icon nes to the Horizontal and add a circular segment
5	Enter Length as 530 ft, Radius as 700 ft, and Direction as Towards Right
6	You can edit the Vertical data such as grades and elevations of alignment in the Vertical tab. In this example, vertical data of alignment is set to 0
7	Click + icon next to the Transverse to define the alignment cross-section at a specific station
8	Enter the cross-section Station as 0 ft
9	Enter the Left Edge to PGL distance as 20 ft. This distance is the length from the left edge to the centerline of the alignment
10	Expand title Quick Tip Completed bridge alignment is illustrated below

	Follow the below steps to define the reference support lines where the piers will be located.
1	Go to Support Line on tree view next to the data spreadsheet
2	Select Bridge and enter the support stations
3	©️ You can copy this data, and paste it to Support Lines. Code Block IP1 Abut1 0 -16.5 IP2 Abut1 0 -5.5 IP3 Abut1 0 5.5 IP4 Abut1 0 16.5 IP5 Pier2 0 -16.5 IP6 Pier2 0 -5.5 IP7 Pier2 0 5.5 IP8 Pier2 0 16.5 IP9 Pier3 0 -16.5 IP10 Pier3 0 -5.5 IP11 Pier3 0 5.5 IP12 Pier3 0 16.5 IP13 Abut4 0 -16.5 IP14 Abut4 0 -5.5 IP15 Abut4 0 5.5 IP16 Abut4 0 16.5

	Follow the below steps to add the insertion points where the bearings will be created.
1	Go to Insertion Point on tree view next to the data spreadsheet.
2	Select a support line as Location.
3	Enter Transverse Offset to relocate the insertion point on the support line.
4	Expand title Quick Tip Skew angle and transverse offset parameters for support lines that have skew > 0 Insertion point layout is given below.

	Follow the below steps to create girder line layouts.
1	Go to Girder Layout on the tree view next to data spreadsheet
2	Click three-dots icon on Supports cell and pick the insertion points
3	Set Type as curved