Staad-dynamic Response Spectrum Method

STAAD Pro Tutorials- Advanced Dynamic Analysis using Response Spectrum Method Dynamic Analysis shall be performed to obtain the design Seismic force, and its distribution to different levels along the height of the building and to various lateral load resisting elements for the following buildings: (a) Regular Buildings: Height > 90m in zones II & III. >40m in zones IV & V (b) Irregular Buildings: All framed buildings Height > 40m in zones II & III. >12m in zones IV & V Types of Dynamic Analysis: Dynamic Analysis may be performed by 1. Response Spectrum Method 2. Time History Method Response Spectrum Method: Qik =Ak ⱷik Pk Wi . User will provide Ak and Wi. In these Ak can be provided by specifying Seismic parameter configuration. Wi can be provided by specifying Selfweight contribution in X, Y, Z direction with factor 1 and dead load and appropriate live load in all three direction. Response Spectrum Method of analysis shall be performed using the Design Spectrum Ah= Z I Sa 2 R g STAAD utilizes following procedure to generate the lateral seismic loads:  User provides the value of Z I as factors for input spectrum. 2 R 

Program calculates time periods for first 15 modes or as specified by the user. (earlier 6 modes)

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Program calculates Sa/g for each mode utilizing time period & damping for each mode.

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The program calculates design horizontal acceleration spectrum Ak for different modes.

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The program then calculates mode participation factor for different modes.

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The Peak lateral seismic force at each floor in each mode are calculated.

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All response quantities for each mode as calculated.

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The peak response quantities are then combined as per method (CQC or SRSS or ABS or TEN or CSM) as defined by the user to get the final results.

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The design base shear VB (Calculated from the Response Spectrum Method) is compared with the base shear Vb (Calculated by empirical formula for the fundamental time period).

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If VB is less than Vb, all of the response quatities are multiplied by Vb/VB as per clause 7.8.2.

Rules for Spectrum Load in STAAD 

Response spectrum Load definition you to define within Seismic Load definition.

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If you have to define all other load case before defining this definition.

Design of seismic shear (VB) Total design seismic base shear VB also any principal direction is given by VB= Ah W Ah= Design horizontal acceleration spectrum value Ah= (z/2) (I/R) (Sa/g) W= Seismic weight of building = Dead load + appropriate amount of imposed load. Note: 1. Live load upto and including 3.0 KN/m2 =25% of imposed load. 2. Live load > 3.0KN/m2 = 50% of imposed load. 3. For calculating design seismic forces imposed load on roof need not be considered. Design Example:

Data: Length of building : 4 bays 5m each=20m Height of building: 4 bays 4.2m in GF and 3.2m for other floor=13.80m Width of building : 3 bays 5m each =15m. Zone V

STEP 1 (Creation of Geometry): New Project 

Select Space  Length =meters; Force=KN;

File Name=Dynamic response Spectrum method  Select  Open Structure Wizard 

Next

Finish.

Change to Frame models from Truss models  Select Bay Frame and double click on it. Length X=20.0m

No. of Bays =4

Height Y=13.6m

No. of Bays=4

Each Bay =5.0m Bay 1=4.2m Bay 2=3.2m Bay 3=3.2m Bay 4=3.2m

Width Z=15.0m

No. of Bays=3 Bay 1=5.0m Bay 2=5.0m Bay 3=5.0m

Apply Transfer Model YesClose. Go to front view. STPE 2 (Member Property): Click General 

Property Define  Rectangle

YD=0.40

ZD=0.40m

 Add  YD=0.45 ZD=0.30AddClose. Highlight YD=0.40 ZD=0.40 Main menu Select

Beam parallel to Y  Assign to selected beam 

Assign Yes. Highlight YD=0.45 ZD=0.30 . Main menu  Select  Beam parallel to X and Select  Beam parallel to Z axis  Assign to selected beam  Assign Yes Close. Deselect the member. STEP 3 (Supports): Go to front view.

Click Support  Create  Fixed Add. Highlight support 2 and select bottom support nodes by windowing using node cursor  Assign to selected nodes  Assign Yes  Close  De select the nodes and change to beam cursor. STEP 4 (Loading ): 1.Seismic Parameter Configuration. 2. Load case 1: DL+LL 3. Seismic loading-Response Spectrum Click Loads & Definition  Seismic Definitions Add. Primary Number 1 loading type: Dead Title: DL  Add  close. Click Load case details Add. Number 2 Loading type: Live Title: LL  Add  close . Click Load case details Add. Number 3 Loading type: Wind Title: WL  Add  close . Click Load case details Add. Click Load Combination  Load Number: 4 Name: 1.5 (DL+LL)  Normal Factor Default :1.5 Load case 1

α1=1.5

Load case 2

α2=1.5 Close.

Click Load case details Add. Click Load Combination  Load Number: 5 Name: 1.5 (DL+WL)  Normal Factor Default :1.5

Load case 1

α1=1.5

Load case 3

α3=1.5 Close.

Click Load case details Add. Click Load Combination  Load Number: 6 Name: 1.5 (DL+LL+WL)  Normal Factor Default :1.2 Load case 1

α1=1.2

Load case 2

α2=1.2

Load case 3

α3=1.2

Close.

Click Load case 1 Add  Member Load uniform Force W1=-40KN/m Gy  Add. Click Load case 2 Add  Member Load uniform Force W1=-20KN/m Gy  Add. Click Load case 3 Add  Nodal Load

FX=25  Add.

FX=20  Add. FX=15  Add. FX=10  Add. FX= 5  Add. Highlight DL=-40 and select beam parallel X  Assign to selected beam  Assign YesClose. Highlight LL=-20 and select beam parallel toX  Assign to selected beam  Assign YesClose. Highlight WL=25 KN and select left side top most node   Assign to selected nodes  Assign Yes. Highlight WL=20 KN and select left side forth floor node 

 Assign to selected nodes  Assign Yes. Highlight WL=15 KN and select left side third floor node   Assign to selected nodes  Assign Yes. Highlight WL=10 KN and select left side second floor node   Assign to selected nodes  Assign Yes. Highlight WL=5 KN and select left side first floor node   Assign to selected nodes  Assign YesClose. Load List: Main menuCommandsLoading Load List (select Load combination from 4 to 6  Load List OkClose. STEP 6 ( Design ): Click Design ConcreteCurrent code :IS456 Define Parameters Fc=30,000KN/m2 Add. Fy main=415000KN/m2 Add Fy sec=415000KN/m2 Add Ratio=3%  Add close. Click Fck=30000 and select the entire structure  Assign to selected beam  Assign Yes. Click Fymain=415000 and select the entire structure  Assign to selected beam  Assign Yes. Click Fysec=415000 and select the entire structure  Assign to selected beam  Assign Yes. Click Ratio=3% and select the entire structure  Assign to selected beam  Assign Yes.

Click Design beam Add. Click Design column  Add. Click concrete Take off Add. Highlight Design Beam and select beam parallel to X  Assign to selected beam  Assign Yes. Highlight Design column and select Beam parallel to Y  Assign to selected beam  Assign Yes. Highlight Concrete Take off and select entire structure  Assign to selected beam  Assign YesClose.

STEP 7 ( Analysis ): Click Analysis/print 

No print  Add Close.

Click post print Define commands Analysis resultsAdd Close, Note: Save the File and Run the Program. STEP 8 (Analysis): From Main Menu  ` Analysis  Run Analysis  Done. Select the member and double click on it  Shear bending  Close. STEP 9 (Results):  Go to post processing mode. Maximize screen. Select various loads and see the deflections. Click Bending Moment icon Mz Results View valueBeam results Bending Moment □ Ends

□ Mid span

Click Shear Force Fy icon Results View valueBeam results

Shear Force □ Ends Click Axial Force icon FX Results View valueBeam results Axial Force □ Ends Design check: Select bottom most GF column  Double click the column  concrete design. Check whether the column fails or not. Similarly check the first floor beam by double click the beam for finding the reinforcement. Report: Click Report set up. Available Input Output

Report Preview Report.

SKETCH:

Selected Sections Supports Loadings Beam End Forces Reactions Beam max. Axial Forces Beam Max. Moments Beam Force Details Summary Ok

Y

STAAD A. Set up

X 1. Global coordinate for Structure : X : as x axis as usual Z Y : as y axis as usual Z : perpendicular to paper to top 2. Local coordinate for individual member along the length of the member is taken as local X axis Two methods of creating Structure Data 1. Using command file 2. Using Graphical user Interface (GUI)

B. Members & Nodes 1. Creation of Geometry 2. General parameters to be fixed 3. Analysis 4. Design Geometry Node: co ordinate of all the points of the plan is to be calculated as Node X Y 1 aaa 000 2 ccc 000 3 File – New –

Indian design code - check New project File Name < > / location < > Length unit , Force Unit - check Space - check Next Finish

Node Give Data for nodes Views available for Front, back, top & isometric Rt. Click - labels - node no – apply – OK Edit ( Top menu bar ) to edit data Add Beam :

Z bbb ddd

STAAD Screen Menu bar - on top Tool bar – on top Page control - left side Data area -Right side Main drawing area - center *After Add beam, grid will appear (/ or from snap node beam) Create ( in Data area) Use linear / Radial / irregular Use plane / constr. line etc.

to add beam or to connect two nodes Add beam from left to right & top to bottom. Node crusher / Beam crusher : for selection of node or beam Rt. Click - labels - Beam no / beam orientation – apply – OK Chage to Isometric view / top Node crusher Select node ( use ctrl key for multiple selection) For column to repeat for floors Geometry ( Top menu bar ) - Translation repeat Global direction Y No of steps – xxx Step spacing – xxx Link step - - check (if required) Ok For beams to repeat for floors Change to front view Beam crusher Select beams to be copied by rubber band method / picking etc. Geometry ( Top menu bar ) - Translation repeat Global direction Y No of steps – xxx Step spacing – xxx Link step - - check (if required) Ok For foundation Similar to above, but y is –ve. Select section General ( left side of screen) – Property Define Type of section Material of section For column : Local z = Global z Local x = Global y i.e length of column Local y = other side. For Beam : Local y = Global y Local x = Global y i.e length of beam Local z = other side i.e. width of beam. Column section Beam section Y Z Z data Give add < enter > . . close < enter>

Y

Node beam Leble View – Structure Diagram Leble

To change Input Unit Input unit Icon / Tool – set current input unit

Member Offset Nodecrusher beam Leble Beam (select) View – Structure Diagram Specification page icon / Leble – Spec. page General Use both start & end point

To get Member information Select – by all – all beams Command – pre analysis print – member property To View3D model Rt. Click – structure - / View – Structure diagram menu To edit input file Edit input file / STAAD editor

After selecting the specific section in the property box, the same is assigned to the members. Ctrl – Select member – assign - save To see the shape and size of column. Rt. Click - labels - structure – section out line - apply – OK For center line Rt. Click - labels - structure – section out line - none – OK To check the property of any section is missing? Select ( top menu bar) – missing attributes – missing property Adding support General ( left side of screen) – Support Create ( left side box) Fixed end Add Front view Node crusher Select the supporting nodes Assign To view whole structure On top menu bar Loading Definition (Seismic definition) General Load – Definition – new Code – IS 1893 – 2002 Zone - (for Zone –3) – 0.16 Response Factor – 5 Importance Factor – 1 Soil factor - 1- hard soil 2- medium soft soil 3- soft soil Add Self weight

*** Add Close (Wind definition) Wind Definition Type – 1, Comment – Wind –1 Add Type – 1 Add Intensity 0

Height 0

1.8

9

Add, Exposure factor – 0 Close Load case detail *( Load case for seismic load) Load case detail Add Number – 1, Loading Type : Seismic ,Title – load case –1, S in X dir Add Close Load case – 1, Add Seismic load, X direction, Factor :1 Add Close Load case detail Add Number – 2, Loading Type : Seismic ,Title – load case –2, S in (-)X dir Add Close Load case – 2, Add Seismic load, X direction, Factor : -1 Add Close Load case detail Add Number – 3, Loading Type : Seismic, Title – load case –3, S in Z dir Add Close Load case – 3, Add Seismic load, Z direction, Factor : 1 Add Close Load case detail Add Number – 4, Loading Type : Seismic , Title – load case –4, S in (-)Z dir Add Close Load case – 4, Add Seismic load, Z direction, Factor : -1 Add Close Load case detail Add

Number – 4, Title – load case –4, S in (-)Z dir Add Close Load case – 4, Add Seismic load, Z direction, Factor : -1 Add Close ________________________________________________________________ *( Load case for Wind load) Load case detail Add Number – 5, Title – load case –5, Wind in X dir Add Close Load case – 5, Add Wind load, Direction X (check) Define y range Minimum Value ( Give data minimum may be 2.1 m) Maximum value (give data) Factor 1 Add Close Load case detail Add Number – 6, Title – load case –6, Wind in (-)X dir Add Close Load case – 6, Add Wind load, Direction X (check) Define y range Minimum Value ( Give data minimum may be 2.1 m) Maximum value (give data) Factor (-1) Add Close Load case detail Add Number – 7, Title – load case –7, Wind in Z dir Add Close Load case – 7, Add Wind load, Direction Z (check)

Define y range Minimum Value ( Give data minimum may be 2.1 m) Maximum value (give data) Factor 1 Add Close Load case detail Add Number – 8, Title – load case –8, Wind in (-)Z dir Add Close Load case – 8, Add Wind load, Direction Z (check) Define y range Minimum Value ( Give data minimum may be 2.1 m) Maximum value (give data) Factor (-1) Add Close ________________________________________________________________ *( Load case for Dead load) Load case detail Add Number – 9, Title – load case –9, Dead Load Add Close Load case – 9, Add Floor Load Pressure = (-) 3.5 KN/ m2 Y range – (Give minimum and Maximum value as per floor condition.) Direction : Global Y Add Close Load case – 9, Add Self weight Add Close Assign ________________________________________________________________ *( Load case for Live load) Load case detail Add Number – 10, Title – load case –10, Live Load Add Close Load case – 10,

Add Floor Load Pressure = (-) 2 KN/ m2 Y range – (Give minimum and Maximum value as per floor condition.) Direction : Global Y Add Close ** (X range and Z range may be changed as per requirement under Load case 10 according to floor size.) ________________________________________________________________ *( Load case for Wall load) Load case detail Add Number – 11, Title – load case –11, Wall Load Add Close Load case – 11, Add Member Load Uniform force W1 : (-) 15 KN/m. Direction GY Add Close Select Assign ** (Load may be according to height and thick ness of wall, For stairs , the load may be calculated and the d1 , d2 value may be given. The load is assigne after selecting beams in each floor) Load case – 11, Add Member Load Uniform force W1 : (-) 4.5 KN/m. Direction GY Add Close Select Assign ** (For parapets) Load case – 11, Add Member Load Uniform force W1 : (-) 12 KN/m. Direction GY Add Close Select Assign

** (For Stairs) ________________________________________________________________ *( Load Combination) *Load case detail Add Define combination Name : Combination Load Case 12: 1(DL + LL) Normal Factor : 1 Transfer dead & live loads to right (i.e. case 9, 10, 11 here i.e dead load, live load, wall load) Add close *Load case detail Add Define combination Name : Combination Load Case 13: 1.5 (DL + LL) Normal Factor : 1.5 Transfer dead & live loads to right (i.e. case 9, 10, 11 here i.e dead load, live load, wall load) Add Close *Load case detail Add Define combination Name : Combination Load Case 14: 1.2 (DL + LL+ S in X) Normal Factor : 1.5 Transfer dead & live loads to right (i.e. case 9, 10, 11,1 here i.e dead load, live load, wall load & Seismic in X direction) Add Close *Load case detail Add Define combination Name : Combination Load Case 15: 1.2 (DL + LL+ S in (-)X) Normal Factor : 1.5 Transfer dead & live loads to right (i.e. case 9, 10, 11,2 here i.e dead load, live load, wall load & Seismic in (-)X direction) Add Close Similarly combine loads for Seismic in both Z dir, Wind in both X & zZ direction, i.e Load case 16- 21) (** Seismic Definition for Spro : 04 & onwards In the seismic definition below self weight 1. The member load copied and pasted with load changing to weight 2. The –ve sign changed to + ve sign, GY to be deleted 3. Also, the Floor load copied and pasted with load changing to weight 4. The –ve sign changed to + ve sign GY to be deleted

5. The live load may be reduced to 0.5 instead of 2 ) ________________________________________________________________

*( Analysis ) Analysis ( from left side menu bar) Perform analysis No print OK Pre print active Define command ( Rt. Side of screen) Support information Add Close Node crusher ? Print support information < active> Select Supports Assign Close Post print Define command ( Rt. Side of screen) Load List Transfer load list 12 ( as foundation is generally designed for LL & DL with Factor of sefty 1) Support Reaction Add Close Node crusher ? Print support reaction < active> Select Supports Assign Close (PERFORM ANALYSIS PRINT SUPPORT INFORMATION LOAD LIST 12 PRINT SUPPORT REACTION ) ________________________________________________________________ *( Design ) Post print Define command ( Rt. Side of screen) Load List Transfer load list 13-21 Add close Design (left side menu bar) Concrete (left side menu bar)

Code : IS 456 (right side menu bar) Select parameter Transfer all parameters to left Transfer following parameters to right Fc Fy main Fy Secondary Max Main Min Main Min Secondary Ok Change unit to Newton & mm Click on the fig on top menu bar Or, Tool Set current input unit Define Parameter Active Fc : 20 N/ m2 Add Close Fy Main : 415 N/ m2 Add Close Fy Seco. : 415 N/ m2 Add Close Max Main : 20mm Add Close Max Sec : 10mm Add Close Min Main : 12 mm Add Close Min Sec : 8mm Add Close Select the structure Assign the above parameters one by one Yes Command Design Beam Add Design Column Add Close Design Column Select column ( Beams parallel to Y axis ) Assign Yes Design Beam Select Beam ( Beams parallel to X & Z axis ) Assign Yes Analyze Run Analysis View out put file Done Result _______________________________________________________________ Fail To see whether any member fails in the output fie Click on the Find (binocular figure)

Fail - find next / Mark all for beams ADE (adequate) - find next / Mark all for columns *( For Printing) Edit Take picture Picture – 1 Title ( eg. Support nodes) Ok File Report Setup Pictures Picture –1 pass to right Picture album Full page Ok File Print purview report Edit Take picture Picture – 2 Continue ……. Copy out put file to wordn fie Select Copy Paste in word file _______________________________________________________________ *( To view output file latter ) Don’t save after run analysis / viewing the output file *( Beam Level) View Option Beam level 1. Horizontal alignment 2. Vertical alignment 3. Font *( Node Level) View Option Beam level 1. Horizontal alignment 2. Vertical alignment 3. Font *( For use of torsion) Design Define Parameter Torsion to be option selected *( For merge beam) Select the two consecutive members to be merged Tool merge selected members Merge Close yes *( To copy a node / member) Select the element Right click Copy

Paste Giving coordinate of X Y Z *( Beta angle) For orientation along Global X axis *( Release) _______________________________________________________________

*( ID from Auto cad Plan in FPS system) Draw the center line Move Select object Specify the base point of displacement as top left corner Destination as origin Format Units Engineering to decimal Scale Select object Origin 0.0254 (to convert to meter) For coordinates Command ID 9( or tools inquiry ID) Select point (–)ve Y considered as positive Z _______________________________________________________________ *( Wall weight) 10” thick wall Weight: 0.28 (wall thickness + plaster)* 1* (3-0.3) * 19.2 Kn / m2 = 14.5 Kn / m (Floor height – beam height) For parapets generally ; 2 Kn. / m at roof top and balcony *( Seismic Parameter) Code IS 1983 Zone = 0.16 (for zone III) Importance factor RF SS

=1

For ordinary residential building

=2

For hospital building

=3

For ordinary construction

=5

For specific construction

=1

Soil Standard for hard soil

=2

Soil Standard for medium soil

ST

=3

Soil Standard for soft soil

=1

Structure Type for RCC frame

=2

Structure Type for Steel frame

=3

Structure Type for Other

*** Member weight – no sign 50% wall load of ground floor for plinth beams 50% wall load of ground floor and 50% load of first floor for ground floor roof beams and so on Floor weight Dead load full Live load 25% , if LL < 3Kn/sqm Live load 50% , if LL > 3Kn/sqm

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