0. Contents
| 1. PartⅠ- EC2 in Gen |
1-1 Overview 1-2 Reinforced Concrete Design Features in midas Gen 1-3 Ultimate Limit State (ULS) Design 1-4 Serviceability Limit States (SLS) Design 1-5 Beam detailing 1-6 Column detailing 1-7 Shear Wall detailing |
|---|---|
| 2. PartⅡ - Model & Design Parameters |
2-1 The Model File 2-2 Performing the Analysis 2-3 Design Parameters 2-4 ULS Design |
| 3. PartⅢ – ULS Member Design |
3-1 Concrete Beam Design 3-2 Section for Design 3-3 Concrete Column Design 3-4 Concrete Wall Design |
| 4. PartⅣ – ULS Member Checks |
4-1 Manually Entering Rebar and ULS Checking 4-2 Modify Beam Section Data 4-3 ULS Beam Member Code Check 4-4 Beam Code Checking |
| 5. PartⅤ – SLS Member Checks |
5-1 Parameters for SLS Checking 5-2 Short/Long Term Elasticity Ratio 5-3 Serviceability Load Combination Type 5-4 Automatic Rebar Input 5-5 View Rebar Data on Section 5-6 Enter Serviceability Limit Control Parameters 5-7 SLS Checks 5-8 Serviceability Checking |
1. PartⅠ- EC2 in Gen
1-1 Overview
Eurocode Design of Reinforced Concrete Building
Model
• 6-story Reinforced Concrete Building
• Element: Wall, Beam
Load & Boundary Conditions
• Self Weight
• Floor Load
• Wind Loads
• Seismic Loads
• Support
Analysis
• Linear Static Analysis
1-2 Reinforced Concrete Design Features in midas Gen
• Gen provides automatic design for beam, column and shear wall.
• Section checking with the given data.
• Ultimate limit state and Serviceability limit state design and/or checking.
• Default load combinations as per Eurocode 2.
• Static wind loads as per Eurocode 1-4: 2005
• Static seismic loads and response spectrum function as per Eurocode 8-1: 2004
• Capacity design as per Eurocode 8-1 can be applied by checking on “Apply EC8:04 Capacity Design”
option in Concrete Design Code dialog box.
• Available Section shapes
- Column : Rectangle, Circular, Hollow circular
- Wall : Rectangle
- Beam : Rectangle, T-shape
Torsion should be checked by the user.
For meshed slab and wall design, we can use Meshed Slab/Wall Design function.
1-3 Ultimate Limit State (ULS) Design
(1) Bending without axial force
• Assuming and have been determined :
where :
where :
= Moment Redistribution Ratio(Factor)
• If (singly reinforced)
where :
is area of compression steel (in layer 1).
• If (Doubly reinforced)
where :
is area of compression steel (in layer 2).
where :
is effective depth to compression steel.
For Minimum and Maximum Required Rebar Area
(2) Bending with axial force
Slenderness Ratio
Second order effects may be ignored if the slenderness λ is below a certain value λlim.
Design Bending moment
• where :
is design moment.
is equivalent first order moment including the effect of imperfection(at about mid height) and may be taken as =
.
where :
is area of compression steel (in layer 2).
where :
is first order end moments at ULS including allowances for imperfections.
; nominal second order moment in slender column
Capacity - Axial force and uni-axial bending moment
• The combinations of and that cause failure of a given column section are illustrated by an interaction diagram as shown below.
• Pure compression, point ①
Buckling failure is not considered.
• Pure tension, point ②
• Balanced failure, point ③
The load and moment at balanced failure, and
, can be calculated by substituting
and
into the above equations.
where, λ=0.8 for fck ≤ 50MPa
λ=0.8-(fck-50)/400 for 50 < fck ≤ 90MPa
λ=0.7 for fck > 90MPa
• For symmetrically reinforced members, the loads and moments at the points ④~⑪ may be calculated by the formula below.
(3) Shear
• Shear resistance of a member with shear reinforcement is equal to:
• In regions of the member where VEd ≤ VRd,c no calculated shear reinforcement is necessary.
• In regions where VEd > VRd,c sufficient shear reinforcement should be provided in order that VEd ≤VRd.
• Members not requiring design shear reinforcement
With a minimum of
• Members not requiring design shear reinforcement
The shear resistance, VRd is the smaller value of :
and
1-4 Serviceability Limit States (SLS) Design
(1) Stress Limitation
• The compressive stress shall be limited to a value k1fck in order to avoid longitudinal cracks under the characteristic combination of loads. A value of K1 can be defined by the user and default value is ‘0.6’.
• If the stress in the concrete under the quasi-permanent loads is less than k2fck, linear creep may be assumed. If the stress in concrete exceeds k2fck, non-linear creep should be considered. A value of K2 can be defined by the user and default value is ‘0.45’.
• Unacceptable cracking or deformation may be assumed to be avoided if, under the characteristic combination of loads, the tensile stress in the reinforcement does not exceed k3fyk. A value of K3 can be defined by the user and default value is ‘0.8’.
• Where the stress is caused by an imposed deformation, the tensile stress should not exceed k4fyk. A value of K4 can be defined by the user and default value is ‘1.0’.
(2) Crack Control
• A limiting calculated crack width, wmax, taking into account the proposed function and nature of the structure and the costs of limiting cracking, should be established.
(3) Deflection Control
• The appearance and general utility of the structure could be impaired when the calculated sag of a beam, slab or cantilever subjected to quasi-permanent loads exceeds span/250.
• For the deflection subjected to characteristic loads can be checked by user defined limit. Default limit is Span/250.
1-5 Beam detailing
The following data are required to be input for Beam design :
• Beam section size (b, h)
• Cover to rebar center
• Bar size
- Main rebar : Up to 5 sizes simultaneously selected, which GEN will use to find the most appropriate.
- Stirrup/Link : One size can be selected.
- P5, P6, P7, P8, P9, P10, P11, P12, P13, P16, P20, P25, P32, and P40 are available.
• Arrangement (= Number of legs of the transverse or shear reinforcement)
- Only one case can be selected among the numbers from 2 to 20.
The following conditions are applied to Beam design :
• Maximum rebar ratio of main rebar, EN 1992-1-1 9.2.1.1
• Minimum rebar ratio of main rebar, EN 1992-1-1 9.2.1.1
• Minimum spacing (= clear distance) of bars, EN 1992-1-1 8.2
• Maximum stirrup spacing, EN 1992-1-1 9.2.2
The following are the Design results provided by Gen :
Main rebar
• Required rebar area satisfying minimum bar spacing
• Number of bars at top and bottom satisfying minimum bar spacing
• Capacity ratio at I-end, middle, and J-end of beam member
• Up to two layers of rebar can be designed
Stirrups/Links
• Required rebar area per unit length
• Spacing of stirrups
• Capacity ratio at I-end, middle, and J-end of beam member
• Check for crushing of compression struts
1-6 Column detailing
The following data are required to be input for Column design :
• Column section size (b, h)
• Cover to rebar center
• Bar size
- Main rebar : Up to 5 sizes simultaneously selected, among which GEN will find the most appropriate.
- Tie/Spiral : One size can be selected.
- P5, P6, P7, P8, P9, P10, P11, P12, P13, P16, P20, P25, P32, and P40 are available.
• Arrangement (= Number of legs of the transverse reinforcement)
- Different number of legs can be applied in the y and z direction.
The following conditions are applied to Column design :
• Maximum rebar ratio of main rebar, EN 1992-1-1 9.5.2
, which can be modified.
• Minimum rebar ratio of main rebar, EN 1992-1-1 9.5.2
• Minimum spacing (clear distance) of bars, EN 1992-1-1 8.2
• Maximum stirrup spacing, EN 1992-1-1 9.5.3 & 9.2.2
The maximum spacing is reduced by a factor 0.6 at the i and j-end of the column.
The following are the design results provided by Gen :
Main rebar
• Number of bars satisfying minimum bar spacing
• Capacity ratio for the most critical part among I-end, middle, and J-end of column member
• Biaxial P-M interaction diagram
Two layers of rebar or bundle bars are not applicable.
Stirrups/Links
• Required rebar area per unit length
• Spacing of ties/spirals
• Capacity ratio for the most critical part of column member (I-end, middle, and J-end)
• Check for crushing of compression struts
1-7 Shear Wall detailing
The following data are required to be input for Shear Wall design :
• Wall section size (L, h)
• Cover to rebar center
• Bar size
- Vertical rebar : Up to 5 sizes simultaneously selected, among which GEN will find the most appropriate.
- End rebar : One size can be selected, then program will find the most appropriate, greater than or equal to the one selected.
- Horizontal rebar : One size can be selected.
- P5, P6, P7, P8, P9, P10, P11, P12, P13, P16, P20, P25, P32, and P40 are available.
• Spacing of vertical rebar
- Select as many spacings as you want program to try
• Spacing of horizontal rebar
• Design method
The following conditions are applied to Shear Wall design :
• Maximum rebar ratio of vertical rebar, EN 1992-1-1 9.6.2
, which can be modified.
• Minimum rebar ratio of vertical rebar, EN 1992-1-1 9.6.2
• Maximum spacing of horizontal rebars, EN 1992-1-1 9.6.3
The following are the design results provided by Gen:
Vertical rebar
• Spacing of vertical rebar
• Capacity ratio for the most critical part among top and bottom of wall
• Uniaxial P-M interaction diagram
Horizontal
• Required rebar area per unit length
• Spacing of horizontal rebar
• Capacity ratio for the most critical part among top and bottom of wall
• Check for crushing of compression struts
2. PartⅡ - Model & Design Parameters
• The Model File
• Performing the Analysis
• Design Parameters
• ULS Design
2-1 The Model File
Typical Floor Plan
Typical Sectional Elevation
2-2 Performing the Analysis
Opening the Pre-generated Model File
1. File > Open Project…
2. Select “EC2 Design”.
3. Click [Open] button.
This tutorial is intended to illustrate design procedure as per Eurocode2. Therefore, the geometry creation, boundary assignment, load application will be skipped. For the aforementioned, refer to “Seismic Design for RC Building” tutorial.
In this tutorial, slab is not included in the model and considered as a rigid diaphragm.
Analysis
1. Analysis > Perform Analysis
2-3 Design Parameters
Load Combinations
1. Results > Combination > Load Combination
2. Click on “Concrete Design” tab.
3. Click [Auto Generation…] button.
4. Option : Add
5. Code Selection : Concrete
6. Design Code : Eurocode2:04
National Annex : Recommended
7. Click [OK] Button.
8. Click [Close] Button.
The program automatically creates design load combinations which can be also modified or deleted by the user.
Design Code
1. Design > Design > RC Design > Design Code…
2. Design Code : Eurocode2:04
National Annex : Recommended
3. Click [OK] button.
Sway Frame Definitions
1. Design > General > General Design Parameter > Definition of Frame…
2. X-Direction of Frame : Braced | Non-sway
3. Y-Direction of Frame : Braced | Non-sway
4. Design Type: 3-D
5. Check off “Auto Calculate Effective Length Factors”.
6. Click [OK] button.
In the non-sway frame, applying 1 for the effective length factor will give conservative results.
Member Assignment
1. Design > General > General Design Parameter > Member Assignment…
2. Assign Type : Automatic
3. Selection Type : All
4. Click [Apply] button.
5. Click [Close] button.
A single Member can be assigned when the member is consisted of a number of beam elements.
Live Load Reduction Factors
1. Design > General > General Design Parameter > Modify Live Load Reduction Factor…
2. Option : Add/Replace
3. Reduction Factor : 0.82
4. Applied Components : All Forces
5. View > Select > Identity…
6. Select Type : Story
7. Select “1F”
8. Click [Add] button.
9. Click [Close] button.
10. Click [Apply] button.
1. Reduction factor for 1st floor columns and walls.
EN 1991-1-1 6.3.1.2 (11)
1. Design > General > General Design Parameter > Modify Live Load Reduction Factor…
2. Option : Add/Replace
3. Reduction Factor : 0.85
4. Applied Components : All Forces
5. View > Select > Identity…
6. Select Type : Story
7. Select “2F”.
8. Click [Add] button.
9. Select “Floor”.
10. Click [Delete] button.
11. Click [Close] button.
12. Click [Apply] button.
1. Reduction factor for 2nd floor columns and walls.
1. Design > General > General Design Parameter > Modify Live Load Reduction Factor…
2. Option : Add/Replace
3. Reduction Factor : 0.9
4. Applied Components : All Forces
5. View > Select > Identity…
6. Select Type : Story
7. Select “3F”.
8. Click [Add] button.
9. Select “Floor”.
10. Click [Delete] button.
11. Click [Close] button.
12. Click [Apply] button.
1. Reduction factor for 3rd floor columns and walls.
Unbraced Lengths (L, Lb)
1. Design > General > General Design Parameter > Unbraced Length(L, Lb)…
2. Option: Add/Replace
3. Unbraced Length – Ly : 0 mm
4. Lz : 0 mm
5. Laterally Unbraced Length: Check on “Do not consider”.
6. View > Select > Select All
7. Click [Apply] button.
1. If “0” is entered for Ly and Lz, unbraced lengths will be calculated by the program based on the nodal coordinates of the beam elements.
Partial Safety Factors
1. Design > Design > RC Design > Partial Safety Factors for Material Properties…
2. Click [Update By Code] button.
3. Click [OK] button.
Concrete and Rebar Properties
1. Design > Design > RC Design > Modify Concrete Materials…
2. Select “C30/37” from Material List.
3. Rebar Selection – Code : EN04(RC)
4. Grade of Main Rebar : Class B
5. Grade of Sub-Rebar : Class A
6. Click [Modify] button.
7. Click [Close] button.
2-4 ULS Design
Design Criteria for Rebar
1. Tools > Setting > Preferences…
2. Click on “Design”.
3. Concrete – Design Code : Eurocode2:04
4. Rebar – Material Code : EN04(RC)
5. Click [OK] button.
Design Criteria for Rebar – Beam Design
6. Design > Design > RC Design > Design Criteria for Rebar…
7. For Beam Design – Main Rebar : click [Rebar…] button.
8. Select P20 and P25.
9. Click [OK] button.
10. Stirrups: P10, Side Bar : P12
11. Arrangement : 2
12. dT: 55 mm, dB : 55 mm
13. Option of Spliced Bars : None
Design Criteria for Rebar – Column Design
14. For Column Design – Main Rebar : click [Rebar…] button.
15. Select P25 and P32.
16. Click [OK] button.
17. Ties/Spirals : P10
18. Arrangement : X: 2, Z: 2
19. do: 55mm
20. Option of Spliced Bars : None
Design Criteria for Rebar – Wall Design
21. For Shear Wall Design – Vertical Rebar : click [Rebar…] button.
22. Select P13 and Click [OK] button.
23. Horizontal Rebar : P13, End Rebar From : P10
24. de : 45 mm, dw : 45 mm
25. Click [Input Additional Wall Data…] button.
26. End Rebar Design Method : Method-1
27. Click [OK] button.
28. Click [OK] button.
3. PartⅢ – ULS Member Design
• Concrete Beam Design
• Section for Design
• Concrete Column Design
• Concrete Wall Design
1. The “Section for Design” function provides Member design of concrete sections based on the section data defined by the user. It allows you to find the appropriate section without re-analysis.
3-1 Concrete Beam Design
1. Design > Design > RC Design > Concrete Code Design > Beam Design…
2. Sorted by : Member
3. Click to expand the dialog box.
4. SEL : select MEMB “1”.
5. Click [Graphic…] button.
6. Click [Detail…] button.
7. Click [Summary…] button.
3-2 Section for Design
1. Design > Design > RC Design > Concrete Code Design > Beam Design…
2. Sorted by : Property
Red N means that negative moment is larger than the resistance for the given section.
Red P means that the positive moment is larger than the resistance for the given section.
Red V means that the shear force is larger than the resistance for the given section.
3. Design > Section for Design…
4. Select “422 WG2” section.
5. Click [Modify] button.
6. Change H from 0.8m to 0.85m.
7. Click [OK] button.
8. Click [Close] button.
9. SEL : select SECT “422”.
10. Click [Re-calculation] button.
1. Check results of Section 422 WG2 change to OK.
3-3 Concrete Column Design
1. Design > Design > RC Design > Concrete Code Design > Column Design…
2. Sorted by : Member
3. Click to expand the dialog box.
4. SEL : select MEMB “41”.
1. As with Beam we may check [Graphic…], [Detail…] & [Summary…] results.
5. Click [Draw PM Curve…] button.
6. Click [Close] button.
3-4 Concrete Wall Design
1. Design > Design > RC Design > Concrete Code Design > Wall Design…
2. Sorted by : Wall ID + story
3. Click to expand the dialog box.
4. SEL : select WID “1” Story “1F”.
1. As with Beam we may check [Detail…] & [Summary…] results.
2. As with Column we may Draw PM Curve
5. Click [Graphic…] button.
4. PartⅣ – ULS Member Checks
4-1 Manually Entering Rebar and ULS Checking
Enter Rebar Data using “Design > Design > RC Design > Modify Beam/Column/Wall Section Data” or “Design > Design > RC Design > Concrete Code Design > Beam/Column/Wall Design > [Update Rebar] button”
1. In this tutorial, “Modify Beam Section Data” will only be illustrated. In the same manner, Column and Wall Section Data can also be defined.
2. Rebar will be MANUALLY entered using “Design > Design > RC Design > Modify Beam/Column/Wall Section Data”
3. Rebar can be AUTOMATICALLY entered using “Design > Design > RC Design > Concrete Code Design > Beam/Column/Wall Design > [Update Rebar] button” (this is illustrated later).
4-2 Modify Beam Section Data
1. Design > Design > RC Design > Modify Beam Section Data…
2. SECT: check on ID “412”.
3.Uncheck “Same Main Rebar Size at Top and Bottom” and “Same Main Rebar Size At I,M and J” .
4. For Main Rebar at “End(I)”
5. For Top Rebar: in front of “Top” and “1” : “4” “P25”
6. Bottom Rebar: In front of “Bot” and “1” :“2” “P20”
7. For Main Rebar at “Center”
8. For Top Rebar: in front of “Top” and “1” : “2” “P20”
9. Bottom Rebar: In front of “Bot” and “1” :“4” “P25”
10.For Main Rebar at “Center”
11.For Top Rebar: in front of “Top” and “1” : “4” “P25”
12. Bottom Rebar: In front of “Bot” and “1” :“2” “P20”
13. Stirrup in “End(I)”
14. Arrangement: “2”
15. Stirrups Space: “100” mm
16. Stirrup in “Center”
17. Arrangement: “2”
18. Stirrups Space: “200” mm
19. Stirrup in “End(J)”
20. Arrangement: “2”
21. Stirrups Space: “100” mm
22.Stirrup: “P10”
23. dT, dB : 0.055m,0.055m
24. Click [Add/Replace] Button
4-3 ULS Beam Member Code Check
6-1. Beam Code Checking
1. In this tutorial, only “Beam Code Checking” will be illustrated. In the same manner, Column/Wall Code Checking can be performed.
4-4 Beam Code Checking
1. Design > Design > RC Design > Concrete Code Check > Beam Checking…
2. Sorted by : Member
3. Results : Strength
4. Click to expand the dialog box.
5. SEL : MEMB “11”
6. Click [Graphic…] button.
7. Option for Detail Print Position: check on “End I.” “Mid.” “End J.”.
8. Click [Detail…] button
9. Click [Summary…] button.
5. PartⅤ – SLS Member Checks
5-1 Parameters for SLS Checking
Concrete long-term and short-term Modulus of elasticity
Serviceability Load Combination
Enter Rebar Data using “Design > Design > RC Design > Modify Beam Section Data” or “Design > Design > RC Design > Concrete Code Design > Beam Design > [Update Rebar] button ”
Serviceability Limit Control Parameters
1. For serviceability check, entering rebar data is required.
5-2 Short/Long Term Elasticity Ratio
1. Design > Design > RC Design > Modify Concrete Materials…
2. Select “C30/37” from Material List.
3. Click button.
4. Click [OK] button.
5. Click [Close] button.
5-3 Serviceability Load Combination Type
1. Design > General > General Design Parameter > Serviceability Load Combination Type…
2. Click [OK] button.
Once the load combinations are generated using “Auto Generation” as per Eurocode2 as in Step 3-1, the program automatically assigns the “Quasi-permanent”, “Frequent” and “Characteristic” load combinations.
5-4 Automatic Rebar Input
1. Design > Design > RC Design > Concrete Code Design > Beam Design…
2. SEL : click [Select All] button.
3. Click [Update Rebar] button.
4. Click [Close] button.
1. By clicking [Update Rebar] button, the rebars designed in this dialog box will be automatically entered into the selected sections.
5-5 View Rebar Data on Section
1. Design > Design > RC Design > Modify Beam Rebar Data…
2. SEL : check on ID “413”.
3. Click [Close] button.
1. In this page, check the Rebar Data entered using [Update Rebar] in the previous page.
2. “In” signifies that Rebar are placed.
3. The entered Rebar Data are displayed.
5-6 Enter Serviceability Limit Control Parameters
1. Design > Concrete Design Parameter > Serviceability Parameters…
2. Option : Add/Replace
3. Selection Type : By Selection
4. Exposure Class : XD1
5. Stress Parameters- k1: 0.6, k2: 0.45, k3: 0.8, k4: 1
6. Quasi-permanent – Limit: 0.3 mm
7. Quasi-permanent Deflection Ctrl: L/250
8. Characteristic Deflection Control – Limit: L/250
9. Deflection Amplification Factor: 1
10. View > Select > Identity…
11. Select Type: Section
12. Select “411: G1”, “412: G2”, “413: G3”, “414: G4”, “415: B1”, “421: WG1”, “422: WG2”
13. Click [Add] Button.
14. Click [Close] Button.
15. Click [Apply] Button.
5-7 SLS Checks
Serviceability Checking for Concrete Beam
1. Serviceability check is provided for Beam members for the following limit states.
- Stress limitation
- Crack control
- Deflection control
5-8 Serviceability Checking
1. Design > Design > RC Design > Concrete Code Check > Beam Checking…
2. Sorted by : Member
3. Results : Serviceability
4. Click to expand the dialog box.
5. SEL : select MEMB “1”
6. Click [Graphic…] button.
7. Click [Detail…] button.
8. Click [Summary…] button.