Seismic Analysis to Indonesia SNI 1726 : 2019
ProtaStructure can now calculate seismic loads in accordance with Indonesia (SNI 1726 :2019 ) seismic code, which is an adaptation of ASCE07.
After selecting the Earthquake Code via Parameter in Building Analysis dialog > Pre-analysis tab, pick Seismic Parameter to access the Seismic Parameters & settings.
Click the i icon for more information and guidance on the parameter.
Ensure to go Edit Storey menu to input the "Live Load Participation" factor as it affects the seismic weight calculation. Also, input the "No. of Rigid Basements" if there are basements modelled.
Parameters
The following are explanation of key inputs in “Parameters” tab :
- Spectrum Angle : Is the angle of the applied seismic forces with respect to the orientation of the structure on plan view; measured anti-clockwise from global horizontal. For example, if a rectangular building is modelled at a rotated angle, then the spectrum angle should be changed accordingly.
- Site Class : User to select. Reference Clause 5.3 : Table 3
- Spectral Accelerations & Soil Factors : Automatically fetched from code tables. Reference clause 6.2.
- Risk Category : User to select. Importance Factor & Seismic Design Category is automatically determined.
- Importance Factor : Automatically fetched from code.
- Seismic Design Category : Automatically fetched from code.
- Building Height : Automatically determined based on Edit Storey menu
- System Category & Structural System Type : User to select for each Direction 1(X) & 2(Y).
- Behaviour Factor (R), Overstrength Factor (Ω0) & Displacement Scale Factor (Cd) are automatically fetched from code table. Reference Clause 7.2.2
- Redundancy Factors (ρ) : User to determine & input.
If a selected Structural System Type is not permitted for a given Seismic Zone and Building Height, an appropriate warning message will be shown.
Analysis
The following are explanation of key inputs in “Analysis” tab :
- Apply Accidental Eccentricity (5%) : Check to apply
- Damping Ratio : User input according to building type
- Number of Horizontal Modes : User input (recommended value = 15)
- Number of Horizontal Modes : User input (recommended value = 15)
- Use user-defined periods in equivalent static analysis : Check to apply & input Period in X & Y direction
ProtaStructure will check the number of modes automatically & issue a warning during analysis if cumulative mass participation is not satisfied.
- Structural Usage or Type : Static field that appears on the reports. User can write anything here.
Structural Irregularities
The following are the list of irregularities checks in “Structural Irregularities” tab :
Irregularities in Plan
- Torsional Irregularity : Automatically detected
- Extreme Torsional Irregularity : Automatically detected
- Diaphragm Discontinuity : User to evaluate & check if exist
Floor meshing with flexible diaphragm option can be used to model buildings with diaphragm discontinuity. Refer here : Slab Model
- Existence if Re-entrant Corners : User to evaluate & check if exist
- Non parallel Axes of Structural Elements : User to evaluate & check if exist
Irregularities in Elevation
- Lateral Strength Discontinuity – Weak Storey : Automatically Detected
- Extreme Lateral Strength Discontinuity : Automictically Detected
- Stiffness Irregularity : Automatically Detected
- Extreme Stiffness Irregularity : Automatically Detected
- Nonuniform Weight (Mass) Distribution : Automatically Detected
- Discontinuous Vertical Load Resisting Elements : User to evaluate & check if exist
- Building with Setbacks : User to evaluate & check if exist
- Inplane Discontinuity in Lateral Force-Resisting Member : User to evaluate & check if exist
Settings
The following are explanation of key inputs in “Settings” tab :
Post Analysis Checks
- Check Relative InterStorey Drift : Tick to perform check. Default drift limit is shown in the next input
- Use user-defined interstorey drift limit ratio : Check to manually over-write the default ratio
- Check Building Height : Tick to perform check.
- Check Wall-Frame Interaction : User to decide
- Check Second Order Effect : Tick to consider this effect using code based slenderness method
- Check Strength Irregularity (Weak Storey) : User to decide
- Check Stiffness Irregularity (Soft Storey) : User to decide
Post Analysis Design Checks
- Check Strong Column – Weak Beam : User to decide. Columns & beams must be designed first before this check can be done.
- Perform Joint Shear Check : User to decide.
- Check Minimum Member Dimensions : User to decide
- Check Building Overturning : User to decide
Response Spectrum Analysis
- Check Cumulative Effective Mass Participation : Tick to check.
- Compare RSA Results with Equivalent Static Load : Tick to consider.
- Use User-defined RSA Scale Factor : Tick to apply and enter factor
- Results Sign Method for RSA : Use "Signs of dominant mode" or "Absolute Value". Refer this article : Results Sign Method for Response Spectrum Analysis
Important Notes / Scope / Limitations
- Refer to “Post-analysis Checks Report” in “Reports” tab for seismic analysis results & clause compliance.
- Refer to "Post-Analysis Design Checks Report" in the "Reports" tab for specific seismic design checks such as "Strong Column - Weak beam" check.
- Elastic and design spectra are automatically calculated.
- Maximum period of vibration checks is automatically made.
- Applicability of Equivalent Static Method is automatically checked.
- RSA results is automatically compared with Equivalent Static Load (if option is ticked in Settings tab). A scaling factor will be automatically applied if required.
- Overstrength factors are automatically applied to design forces.
- If there is a basement in the building, a two-stage approach is used to analyze the building. Basement and superstructure is analyzed separately in different load cases and the results are combined for the design. All these are done automatically (user input is not required).
- Results for cracked and uncracked section analysis can be combined in same design combination.
- For “Joint Shear Check” the stirrups (links) are not considered.
Related Articles
Seismic Analysis to Philippines NSCP2015
ProtaStructure can now calculate seismic loads in accordance with Philippines (NSCP2015) seismic code, which is an adaptation of UBC97. After selecting the Earthquake Code via Parameter in Building Analysis dialog > Pre-analysis tab, pick Seismic ...
Results Sign Method for Response Spectrum Analysis
Response Spectrum Analysis calculates and combines the pseudo maximum responses of natural vibration modes against a given design spectrum by assuming each mode as an independent single degree of freedom system. During the combination of modal result ...
Vertical Earthquake Effects
ProtaStructure can reflect the effects of vertical earthquake action in design by providing two methods: Approximate Static Approach Modal Spectrum Analysis Method In Approximate Static Approach, vertical vibration modes and a dedicated vertical ...
Seismic Analysis to India IS 1893-2016
ProtaStructure can calculate seismic loads in accordance with India (IS 1893-2016) seismic code, which covers the key parts of IS codes. Firstly ensure that required seismic code is selected. Refer to this article : Seismic Load - Basic Guide Go to ...
Seismic Load - Basic Guide
General You will learn how to incorporate the basic seismic loading into your model. You will know how to view & check the seismic mode shapes It is very important that the user to refer the relevant earthquake code for detail explanations of the ...