FCM bridge

The Wizard automatically generates the model data of a bridge constructed by an FCM, Free Cantilever Method, by entering simple variables. The data include elements, boundary conditions, tendon placement, construction stages, etc. for a bridge composed of PSC (prestressed or post-tensioned Concrete) Box sections. Please refer to "Advanced Applications" for the analysis procedure and model data generation using the FCM Bridge Wizard.

Note 1
FCM Wizard permits us to define true construction conditions even when a bridge is constructed asymmetrically and when span lengths vary. FCM Wizard can also reflect the change of polynomial order for tapered sections, adjusting the time of grouting, etc.

Note 2
The input data in FCM Bridge Wizard are saved in the corresponding dialog boxes once the Wizard is executed normally. We can recall the input data after closing the Wizard and subsequently check, modify and re-execute the Wizard. In addition, Wizard data can be saved as a file with .wzd extension, which can be recalled even after closing the program.

From the Main Menu select Structure > Wizard > FCM Bridge

Bridge Model Data Type

Select a Data Input Type.

Type 1: Define PSC Box Section and tendon layout in conformity with the form provided by the Wizard.

Type 2: The user defines PSC Box Section and tendon layout manually. The Section defined by the user can be recalled and thus, multi-Cell Section can be defined.

Model tab

Define the materials, sections and overall configuration of a bridge in conjunction with the composition of segments to generate construction stages.

Material (Girder): Material for girders

Material (Pier): Material for piers

Pier Section: Section shape for piers

Note
Click the buttons to the right of Material and Pier Section to create new or modify the existing materials and section.

Stage Duration
Specify the time it takes to install the formwork; place the reinforcing and sheaths; and cast and cure the concrete (i.e., total time to construct a segment which constitutes a construction stage). In the case of cast-in-place concrete, the Stage Duration must be greater than the Member Age of the segment being cast (activated) in the corresponding construction stage.

Number of Piers: Total number of piers (a twin pier is counted as one)

Radius
Check on to specify the radius of a curved bridge with a single curvature.

Convex: Convex curvature bulging to the general +ve direction of the Global Y-axis on Global X-Y plane starting from the GCS origin tangent to the Global X-axis   

Concave: Concave curvature bulging to the general -ve direction of the Global Y-axis on Global X-Y plane starting from the GCS origin tangent to the Global X-axis

Pier Table

P.T. B
Specify the top and bottom dimensions of the pier table referring to the guide diagram.

The number of diaphragms and the dimensions of the pier table are specified for each pier separately.

The list of the same number of pier tables is automatically generated on the basis of the Number of Piers entered in the above dialog box. The following items can be specified after assigning the desired pier tables requiring data changes:

Pier Table Type
Referring to the guide diagram, select the diaphragm type, and enter the shape and dimensions of the pier table. A non-symmetrical FCM bridge may be modeled by specifying different dimensions at the left and right.

Apply the data entered in Pier Table Type to the assigned pier tables.

Initialize the data by deleting the entered data for the assigned pier tables.

Key Segment

K1, K2
Referring to the guide diagram, enter the lengths of the key segments (linking elements).

Enter the length of each Key Seg. and the numbers of prismatic segments (straight section zones) on each side of the Key Seg.

A number of Key Seg's. relative to the number of piers are automatically generated and listed in the dialog box. Enter the following items after selecting theKey Segs. whose data are to be changed:

Key Segment Length: Length of Key Seg.

Left Straight Segment No: The number of prismatic (straight) segments to the left of the Key Seg. At least '1' is recommended for the Key Seg formwork.

Right Straight Segment No: The number of prismatic (straight) segments to the right of the Key Seg. At least '1' is recommended for the Key Seg formwork.

Apply the entered data to the selected Key Segs.

Initialize the data entries by deleting the entered data for the selected Key Segs.

Pier

H, C
Referring to the guide diagram, enter the height and the spacing of the twin pier.

Note
A single pier can be modeled if the spacing (C) is defined as '0'.

FSM

The FSM zone is considered as one segment. In order to specify tendon anchor locations define the lengths of the elements. The FSM zones are conventionally constructed with full shoring (FSM, Full Staging Method).

Note
Confirmation is required as to whether or not the elements in the FSM zones will be divided. If it is not divided, all the tendons will be anchored at the same end point. This functionality is added to avoid analysis errors related to anchoring bottom tendons at a single element

Zone

Specify the lengths of the segments in the buttress span (Zone 1) and the interior span (Zone2). Enter the lengths from the closest to the Pier table to the farthest from the Pier Table.

For each pier table, enter the lengths of the left and right segments. This feature becomes handy when the FCM bridge model involves non-symmetrical configurations or the spans vary.

The dialog box displays the auto-generated list of segment lengths based on the number of pier tables. Select the pier tables that require length changes and input the following:

Zone1, Zone2: Lengths of the segments located to the left and right of the first interior pier table. The Zone 1 represents an end span, and the Zone 2 represents the interior spans (when is checked off).

Note
If is checked on, the Zone 1 and Zone 2 represent the segments to the left and right of each pier table respectively.

Curvature1, Curvature2: Exp.: Highest exponents of the curvature equations defining the variable sections of the left and right segments in the Zone 1 and Zone 2 respectively on each side of each pier table. The exponent ranges between 1 and 2.

Apply the entered data to the selected Pier Tables.

Initialize the data entries by deleting the entered data for the selected Pier Tables.

Note
The Advanced Zone dialog box enables us to incorporate changing spans and model an FCM bridge constructed non-symmetrically. The construction stages are automatically composed in the process. The numbers of left and right segments must be equal. Also, all the piers must have equal numbers of the left and right segments although their lengths may be different. The geometry is defined for each "T" shape (left/right cantilevers and a pier) separated by the Key Segs.

In practice, not all the pier tables are constructed simultaneously. For this reason, we specify the relative times (time differences) for constructing the pier tables. The pier table at the farthest left pier retains the number 1. The entered Days determine the construction stages.

Note
In an FCM bridge, because not all the piers are constructed simultaneously, the timing for constructing cantilevers also varies from pier to pier. Accordingly, when a Key Segment is cast, the cantilevers on both sides will have different ages. The Pier Table Placing is defined to reflect the age differences into the analysis. When we enter the construction time difference in the Pier Table Placing dialog box according to the construction schedule, MIDAS/Civil imposes Time Load for Construction Stage to the pier table and cantilever constructed earlier. The time load simply reflects the passage of time for changing material properties, creep and shrinkage.

Specify the initial age, which is the maturity of concrete at the start of a construction stage (i.e., aging of concrete taken place in the immediately preceding stage). The member age is used to reflect the compressive strength (modulus of elasticity), creep and shrinkage. (Input unit: Day)

Note
The initial age represents the duration of curing in-situ concrete subsequent to installing re-bars and formwork/falsework and casting concrete. The actual aging takes place in the latter part of (n-1)th stage, and that duration becomes the member age at the start of the nth stage.

Note
FCM Wizard Automatically generates Element groups, Boundary groups and Load groups to create a bridge model. Refer to Define Structure Group, Define Boundary Group, and Define Load Group.

Section tab - Type 1

Section Type

1 Cell: No interior web is present.

2 Cell: A single interior web partitions the PSC box.

Enter the maximum section dimensions for the pier table and the dimensions of the Key Segment.

H1, H2..., B1, B2..., T: Dimensions related to the Key Segment part (Minimum section)

H2-1, H3-1: Dimensions related to the pier table (Maximum section)

Note
Between the two sections, the profile of the bottom flange takes the form of the curvature with the defined exponent, n. The number of prismatic segments is defined in the Advanced Key segment dialog box, and the exponent for the curvature equation is defined in the Advanced Zone dialog box. Refer to "Tapered Section Group" for defining variable sections.

View Option

Bitmap
The dimension guide diagram is displayed in the dialog box.

Drawing
Using the dimensions, the maximum and minimum sections are displayed in the dialog box to a true scale.

Update
If Drawing is selected, the sections are regenerated to reflect the revised dimensions.

Form Traveler Load (include form load)

Enter the weight of Form Traveler. It is applied to the construction stages as load groups identified such as 'FT-P2Seg3'. The last number signifies the stage number.

Note
The weight of Form Traveler used to install Key Segs. is applied as load groups identified such as "FT-KeySeg2. The last number signifies the Key Seg number. The numbering starts from the left to right.

Include Wet Conc. Load
The weight of Wet Concrete is calculated based on the section size and added to the load.

Note
The auto-calculated weight of wet concrete is saved as load groups identified such as "WC-P2Seg 3" The last number signifies the stage number. The program activates each load group in the corresponding construction stage and deactivates it at the next stage.

P
Specify the weight of the form traveler. The weight of the concrete need not be included as it is separately calculated and added.

e: Eccentricity to account for the moment due to the weight of concrete (refer to the diagram)

Section tab - Type 2

When Type 2 is selected, this tab allows the user to define Sections for Pier Table and Center (Key Segments, FSM) by importing previously defined Sections.

User Define

Center: Select a Section previously defined by the user for Center. If a Section has not been defined, click  to define a Section.

Pier Table: Select a Section previously defined by the user for Pier Table.

Diaphragm: Select a Section previously defined by the user for the Support of Pier Table. This is enabled only when the Advanced option of Pier Table is selected on Model tab.

Update Display: Update the Section configuration.

Tendon tab - Type 1

Tendon and Prestress

Specify the tendon placement and magnitude of prestress. Check off the box not to consider the tendon placement.

Tendon Property

Specify the types of the top and bottom tendons. Click the to the right of the selection fields to prompt the "Tendon Property" dialog box to add or modify tendon properties.

Jacking Stress

Specify the tensioning stresses for the top and bottom tendons.

Su: Ultimate tensile strength

Sy: Yield strength

Tendon Anchorage Number

Specify the number of tendons anchored to each segment.

: Number of top tendons anchored

Note
"Unequal" may be selected in the dialog box to specify the number of top tendons anchored to each segment of each pier separately.

: Number of bottom tendons anchored to each segment in the span of the buttress and FSM side (end span).

Note
"Unequal" may be selected in the dialog box to specify the number of bottom tendons anchored to each segment of each end span, left and right separately.

: Number of bottom tendons anchored to each segment in an interior span.

Note
"Unequal" may be selected in the dialog box to specify the number of bottom tendons anchored to each segment of each interior span separately.

Section Type

1 Cell: No interior web is present.

2 Cell: A single interior web partitions the PSC box.

H1, H2, H3...

Referring to the guide diagram, enter the tendon locations and spacings.

Referring to the guide diagram, enter the positions and spacings of the top tendons located within the width of the web.

Enter the number of tendons in various positions. "Unequal" may be selected to specify irregular tendon placements - top tendons over each pier and bottom tendons in each span.

Note
N7 and N8 represent the numbers of tendons placed in the FSM zone.

Anchorage Position

Define the anchorage position of the bottom tendons in the segments.

x: Anchorage distance relative to the segment length (refer to the diagram)

Note
Anchorage Position is defined to consider the anchorage of tendons installed inside for PSM (Precast Segment Method).

Top Tendon Grouting

Specify the timing of grouting top tendons. Once the ducts are grouted, the transformed section properties are subsequently considered. The input signifies the timing of incorporating the transformed properties.

Prestressing step
Grouting takes place at the time of tensioning the tendons.

Every n Stage
Grouting takes place at every n stages. If n=1is entered, the grouting is assumed to take place at the next stage after the corresponding tendons are stressed. If n=2 is entered, the grouting is assumed to take place at the third stage after the two corresponding segments have been stressed.

Tendon tab - Type 2

Tendon and Prestress

Specify the tendon placement and magnitude of prestress. Check off the box not to consider the tendon placement.

Tendon Number

Tendon Group

Name of Tendon Group

Group Baseline

Referring to the guide diagram, enter the Baseline of each Tendon Group. For example, to define the tendons of PSTG (top slab tendons of the pier table), use one of the tendons of PSTG as the Baseline reference and specify Bi to enter the remaining tendons. The use of Group Baseline simplifies the input of tendons of each Tendon Group.

Tendon

Bi: The horizontal distance from the Baseline to the tendon. The left of the Baseline is considered (+) positive and the right side is considered (-) negative. If 0 is specified for the Baseline, the horizontal distance from the center of the section to the tendon is entered.

Hi: The vertical distance from the section top edge or bottom edge to the tendon.

For PSTG and PWTG, the vertical distance from the section top edge to the tendon is specified.

For CSTG, CWTG, ASTG and AWTG, the vertical distance from the section bottom edge to the tendon is specified.

Anchorage

Ai: Enter the distance from the Segment end to the point of Anchorage in the longitudinal direction. Enter 0 for the Anchorage, which is located at the Segment end.

Bi: Enter the distance from the Baseline to the Anchorage across the section.

Hi: Enter the vertical distance from the section top edge or bottom edge to the Anchorage.

For PSTG and PWTG, enter the vertical distance from the section top edge to the Anchorage.

For CSTG, CWTG, ASTG and AWTG, enter the vertical distance from the section bottom edge to the Anchorage.  

Ri: Enter the radius of curvature of the tendon.

Θi: Enter the slope of the tendon.

Segment: Select the Segment in which the Anchorage is included. By default, P.T. (Pier Table) is specified. If the Anchorage is located at a Segment other than P.T., select a relevant Segment. Segments in the drop-down list are automatically generated in an equal number of Segments entered in the Model tab.

FSM Anchorage

Define the Anchorage positions of the tendons in side spans. This becomes active only for the Tendon Groups (ASTG and AWTG) of side spans.

Ai: Enter the distance from the Segment end to the point of Anchorage in the longitudinal direction. Enter 0 for the Anchorage, which is located at the Segment end.

Bi: Enter the distance from the Baseline to the Anchorage across the section.

Hi: Enter the vertical distance from the section top edge or bottom edge to the Anchorage.

For PSTG and PWTG, enter the vertical distance from the section top edge to the Anchorage.

For CSTG, CWTG, ASTG and AWTG, enter the vertical distance from the section bottom end to the Anchorage.

Ri: Enter the radius of curvature of the tendon.

Θi: Enter the slope of the tendon.

Segment: Select the Segment in which the Anchorage is included. By default, P.T. (Pier Table) is specified. If the Anchorage is located at a Segment other than P.T., select a relevant Segment. Segments in the drop-down list are automatically generated in an equal number of Segments entered in the Model tab.

Tendon Property

Specify the types of the top and bottom tendons. Click the  to the right of the selection field to prompt the "Tendon Property" dialog box to add or modify tendon properties.

Jacking Stress

Specify the tensioning stresses for the top and bottom tendons.

Su: Ultimate tensile strength of tendons

Sy: Yield strength of tendons

Top Tendon Grouting

Specify the timing of grouting top tendons. Once the ducts are grouted, the transformed section properties of tendon and grout are subsequently considered. The input signifies the timing of incorporating the transformed properties.

Every n Stage
Grouting takes place at every n stages. If n=1 is entered, the grouting is assumed to take place at the next stage after the corresponding tendons are stressed. If n=2 is entered, the grouting is assumed to take place at the third stage after the two corresponding segments have been stressed.

Note
FCM Tendon Viewer shows the input state of Section and Tendon at Center and Pier Table. In the diagram above, the gray area represents the section at Center and the area enclosed by solid lines represents the section at Pier Table. The dots represent Tendons and the rectangle ( ) enclosing a dot represents anchorage. The tool bar icons in the middle signify Zoom all, Zoom window, Zoom in and Zoom out respectively. The mouse wheel is used to Pan the view. The figure below shows a view when the Pan function is executed

Place the mouse cursor over the dots representing Tendon or Anchorage, and right click to prompt a tool-tip and display Tendon and Anchorage information at the bottom of the View.

The user can define colors for Tendon Groups by selecting a Tendon Group from the combo box at the bottom followed by assigning a color.

Tendon Groups are expressed differently for Center and Pier Table as follows:

Center: CSTG, CWTG, ASTG, AWTG

Pier Table: PSTG, PWTG

Open the data saved as in the *.wzd file type in the FCM Bridge Wizard. By using this function, we can re-execute midas Civil and subsequently check and modify the previously entered data within the Wizard.

Save the data entered in the FCM Bridge Wizard as the *.wzd file type.