Field Splices
The LEAP Bridge Steel Field Splice command allows definition of field splice locations within a bridge and the ability to check and existing field splice or design an optimized field splice. All user defined load combinations are automatically used to define the field splice. Field splice conforms to the related AASHTO LRFD Articles.
Field splice locations are defined on a member by member basis. Field splices can be located relative to the end of a member, supports, cross-frames, stiffeners or section breaks. Once field splice locations are defined on a member they can be copied to other selected members or all members.
To initiate Field splice select the command from the Superstructure command list:
The field splice screen will appear similar to that shown below. All field splice operations, from defining the splice locations to viewing results graphically and in report form, are done from this screen.
Field Splices General Design Procedure:
The following describes the general procedures used by the LEAP Bridge Steel Field Splice design optimization process. This process is invoked when Design is selected as the processing mode on the Field Splice Settings dialog box.
Note that the process described below is repeated for each load combination defined in the LEAP Bridge Steel Loads dialog box. The controlling conditions for flange and web splice plates, including main member checks, are determined and reported from checks made for each load combination including Strength, Service and Fatigue.
Flange Splices design:
- The process starts with
the minimum outer and inner plate thickness as specified on the Flange splice
tab on the Settings dialog.
- For the current outer splice plate thickness, the inner splice plate is set such that the area of the two inner splice plates equals the area of the outer splice plate.
- The following checks
are made at each plate thickness increment until the ratio of demand/capacity
is less than one.
- Flexure Yielding of Gross Section of Inner Splice Plates +LL and –LL
- Flexure Yielding of Gross Section of Outer Splice Plate +LL and –LL
- Flexure Yielding of Net Section of Inner Splice Plates +LL and –LL
- Flexure Yielding of Net Section of Outer Splice Plate +LL and –LL
- Flexure Yielding of Net Section of Flange Plate +LL and –LL
- Fatigue of Inner Splice Plates
- Fatigue of Outer Splice Plate
- The number of bolts in the flange is determined given the user entered "Number of bolt columns (Long)" and the fact that a minimum of two bolt rows (Transv) will be required.
- Plate thicknesses are incremented by 1/16" for each iteration if any of the checks fail. The process then repeats with an incremented plate thickness.
Depending on the relative thickness of the left and right girder sections at the field splice, filler plates will be sized and included in the flange field splice checks.
Web Splices design:
- The web plate thickness is set to the minimum value as specified on the Web tab of the Settings dialog.
- The minimum number of bolt columns (Vert.) is set to 2. (the maximum is 10)
- The minimum and maximum number of bolt rows (horizontal) is set based on user specified minimum and maximum vertical bolt spacing (as calculated based on bolt diameter and current web plate thickness, vertical edge distance, minimum top and bottom clearances). The number of bolt rows is incremented by one at a time as required.
- For each increment of web
plate thickness:
- The number of columns is incremented from the minimum to the maximum number (i.e. 2 to 10).
- If the max. ratio is less than 1.0 the web plate is optimized for the thickness and number of bolt rows and columns in this iteration -> FINISH
- If the Max ratio is greater than 1.0, increment number of rows then number of columns