	Applies To
	Product:	AutoPIPE
	First Affected Version:	05.00.00
	Found in Version:	10.01.00
	Fixed and Released in Version:	11.00.00
	Area:	Analysis
	Severity:	Critical
	Backlog Issue Number:	522111

Problem Description

AutoPIPE allows users to place more than one time history profile in a time history load case. This can be done either through ground motion by applying different TIH files in each direction, or through normal time history by applying more than one TIH file in a time history location file (AutoPIPE supports four per load case)

Reason

For all models created after AutoPIPE 5.0, unexpectedly large results (displacement, forces, moments, stresses) for time history load cases occur if any of the following are true:
1. There exists at least one time history ground motion using more than one time history profile; or
2. There exists at least one time history using a time history location file with more than one time history profile

Time history locations are stored externally as THL files, name designation defined by the designer.
Time history profiles are stored externally as TIH files, name designation defined by the designer.

Steps to Repeat

1. Open model. Note that there exists two TIH files that are identical.

2. Open the AutoPIPE model and review the time history definitions. There are two time history load cases, where M1uses the same TIH files for X and Z axes and M2 uses both TIH files, one each for X and Z axes

3. Run the analysis and generate the output report

Reviewing the displacement section, M1 produces the correct displacements, whereas M2 produces higher displacements. Additionally, Forces, Moments and Stresses are higher for M2 than they are for the correct values produced by M1. This increase in stress represents an overly conservative result from time histories using more than one TIH file.

Workaround

For time histories that require more than one time history profile, employing a maximum of one TIH file in a THL file mitigates this error. For example, if two TIH files are needed for a time history load case, create a THL file for each TIH file. Isolating the TIH files into each THL, including the locations and directions the profile is applied to the structure. If more than four profiles are required, splitting the time history into multiple load cases and combining them via algebraic sum in the post-processor yields the correct results.

For ground motion that require more than one time history profile, it is required to split the load cases into one for each time history profile and combine them via algebraic sum in the post-processor. For example, if a ground motion is needed for three different time history profiles, one along each global axis, the ground motion shall be split into three load cases, one for each time history profile. Code and non-code combinations shall be created that then combines load cases via algebraic sum.

Solution

For both time history location files using more than one time history profile and ground motion time history load cases using more than one time history profile, AutoPIPE shall evaluate the displacements for each load direction, producing results for all three directions. These directions shall finally be combined using algebraic sum after all directions are considered.

Also See:

Critical and High issues released in AutoPIPE CONNECT v.11.0