In An important item which concerns moving-load analysis , there is one important item that you should be aware of. Certain types of vehicles, such as the AASHTO "double truck" that certain vehicle types, including the AASHTO double truck (HL-93S), apply only for negative moments moment at supports and for interior reactions. This is defined by checking the appropriate items in the Usage data set as shown belowThese response quantities are defined under Usage on the General Vehicle Data form shown in Figure 1:

Image ModifiedNow, SAP2000 does not "know" what elements and their internal forces represent negative moments

Figure 1 - General Vehicle Data

Next, structural objects which exhibit negative moment at supports or interior reactions , unless we designate these elements for SAP2000 as such. For this purpose, the program uses the concept of should be designated using vehicle response components, which is as described in the CSI Analysis Reference Manual, chapter "Bridge Analysis", section " (Vehicle Response Components" and further explained in , page 446) and the attached notePDF.

Depending on the particular model, you may consider the following two approaches apply To satisfy AASHTO requirements, HL-93S vehicles should be applied using either of the following two methods:

• Coordinate these response components with the HL-93S vehicle

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• by assigning vehicle-response-component overwrites through Assign > Frame Loads

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• or Area Loads

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• > Vehicle Response Components

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• . For complex models, however, this process may require significant effort.

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• Generate conservative results by modifying the vehicle definition to include

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• Usage > All Other Responses

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• . As a result, the HL-93S vehicle

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• is used for all

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• response measures, which is appropriate when the positive moments

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• induced by HL-93S

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• vehicles are

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• similar to

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• those of HL-93K

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• vehicles.

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Attachments

• Vehicle Response Components (PDF File, 122 KB)