IES VisualAnalysis User's Guide
ASCE Load Helper
The ASCE Load Helper is used to apply the predefined ASCE 7 dead or live loads to nodes, members, plates, or areas. The loads that are defined in the helper are saved in a UserLoads.xml file in the IES Data Folder and are available for future projects.
Dead loads are defined using the | command on the main menu. In the Dead Load tab, various ASCE materials can be selected, combined, and a custom name can be given to the group of components.
Live Loads are defined using the command on the main menu. In the Live Load tab, various ASCE Live Loads can be selected or Custom Live Loads can be created.
ASCE Loads can be applied to nodes, members, plates, or areas. ASCE Dead Loads and ASCE Live Loads can only be applied in Service Cases that have Dead and Live load sources, respectively. When adding a load to the model, an ASCE 7 Load can be selected in the Magnitude section if one is available. Tributary widths must be specified for nodal force loads and uniform member loads since ASCE 7 Loads are defined as uniform pressures.
The ASCE Load Helper can also assist in determining the Design Spectral Acceleration parameters, SDs and SD1, as well as the Seismic Design Category of the structure using ASCE 7-16 Chapters 11 and 12.
The Load Helper's Seismic Load features can be found by launching the dialog from the "Calculate SDs & SDC" field found in the tab under the IBC Seismic Loading category. The left side of the dialog can be used to enter site specific information, such as the Site Class and the mapped spectral response acceleration parameters, Ss and S1. Seismic calculations are displayed on the right side of the window, updating with each change. After exiting the dialog using the "OK" button, the Risk Category, Seismic Design Category, and the Short Period Design Spectral Acceleration (SDs) parameters are set for the current model. More information on these parameters can be found in Project Setting topic.
The Site Information input parameters are defined as follows:
| Risk Category |
Risk - Risk category assigned to the structure. |
| Site Information |
Specification - The ASCE7 specification used for the seismic calculations. Site Class - The classification assigned to the site based on the types of soils present. Lat/Long Search - Search for Ss, S1, and TL values using latitude and longitude coordinates and USGS Seismic Design Web services. Ss, g - The mapped MCER spectral response acceleration parameter at short periods. S1, g - The mapped MCER spectral response acceleration parameter at a period of 1-second. Long Period Transition - The mapped long-period transition period. Determine SDC from SDs only? - Should the seismic design category be chosen from the SDs value only? Please verify that the criteria of ASCE 7-16 Section 11.6 is met prior to changing this setting. Override Fa - Should the short-period site coefficient be overridden? Fa Override - The value to use for short-period site coefficient if overridden. Override Fv - Should the long-period site coefficient be overridden? Fv Override - The value to use for long-period site coefficient if overridden. |
The Seismic Design Category result parameters are defined as follows:
| Maximum Considered Earthquake |
Fa - The short-period site coefficient used for the calculations. Fv - The long-period site coefficient used for the calculations. SMs, g - The site modified maximum considered earthquake spectral response acceleration at short periods, 5% damped. SM1, g - The site modified maximum considered earthquake spectral response acceleration at a 1-second period, 5% damped. |
| Design Spectral Response |
SDs, g - The design spectral response acceleration at short periods, 5% damped. SD1, g - The design spectral response acceleration at a 1-second period, 5% damped. |
| Seismic Design Category |
Risk Category - The risk category assigned to the structure and used for the calculations. SDC - The seismic design category of the structure. SDC - Short Period - The seismic design category of the structure, based on SDs. SDC - 1-second Period - The seismic design category of the structure, based on SD1. |
Note: Additional Seismic Design Criteria and Design Requirement calculations are available in the stand-alone Load Helper utility. To download, visit www.iesweb.com/downloads.