Slabs in Midas Gen

Slabs in Midas Gen
  • Slabs in Midas Gen

  • Views 1

  • Downloads 0

  • File size 6MB
  • Author/Uploader: markespino

Automesh and slab / wall design tutorial

Meshed Slab and Wall Design as per ACI318-11

Program Version Revision Date

Gen 2013 (v2.1) Oct. 04, 2013

http://en.midasuser.com Midas Information Technology Co., Ltd.

Midas Information Technology Co., Ltd.

Step

00

Overview

Automesh and slab / wall design tutorial

Contents Step 1: Model & Automesh Step 2: Load Definition Step 3: Design Parameters and Frame Design Step 4: Slab/Wall Design  Slab flexural design  Slab shear checking  Serviceability parameter  Slab serviceability checking  Wall design

Midas Information Technology Co., Ltd.

1/49

Step

00

Introduction of Meshed Slab / Wall Design

Automesh and slab / wall design tutorial

In Gen 2013 (v2.1), meshed slab and wall design as per ACI318-11 has been newly implemented. The following design features as per ACI31811 are now available in midas Gen.

Element type

Member type

Strength Check

Serviceability Check

Beam element

Beam, Column

Bending without axial force Bending with axial force Shear

Wall element

Wall

Bending with axial force Shear

Slab

Flexural design (Wood-Armer moment) Punching shear checking

Deflection Control (Uncracked)

Wall

In-plane Stress

Plate element

This tutorial is intended to explain how to perform meshed slab and wall design. For this reason, the procedure for general frame design process were not included.

Midas Information Technology Co., Ltd.

2/49

Step

00

Usage Tip [ Task Pane ]

Automesh and slab / wall design tutorial

Using the task pane, we can display work procedure, required input items and optional input items for each analysis and design case. Using the User Defined Task Pane, the user can create a Task Pane manually. For the meshed slab wall design feature, TDF file was provided with the tutorial model files for the user’s convenience. In order to import the User Defined Task Pane, please follow the procedure below. 1. Go to Task Pane tab in the left panel of the midas Gen window. 2. Click [Task Pane] text from the drop down menu. 3. Click [Import User Defined Page]. 4. Select “slab desig.tpd” file and click [Open] button.

2 3

1 4

Midas Information Technology Co., Ltd.

3/49

Step

00

Overview 16 m

9m

23 m

7m

5m

9m

Automesh and slab / wall design tutorial

3m

12.5 m

3m

2m

3m

6m

Sectional Elevation

3m

3m

Typical Floor Plan

Midas Information Technology Co., Ltd.

4/49

Step

00

Details of the building (1)

Automesh and slab / wall design tutorial

Applied Code

• ACI318-11

Girder Section Designation

Story

Section ID

Section Dimension (mm)

Girder

1~5F

1

500 x 400

Materials

• Beam : Concrete Grade C4000 • Column: Concrete Grade C4500

Column Section Designation

Story

Section Number

Section Dimension (mm)

Column

1~5F

2

500 x 500

Slab/Wall Thickness

Midas Information Technology Co., Ltd.

Designation

Story

Thickness ID

Thickness (mm)

Slab

1~5F

1

200

Wall

1~5F

2

250

5/49

Step

00

Details of the building (2)

Automesh and slab / wall design tutorial

Applied Load

Load

Details

Dead Load

Self Weight

Weight Density: 23.56 kN/m

Live Load

Pressure Load

Shopping areas : 4.0 kN/m Office areas : 2.0 kN/m

Wind Load

Earthquake Load

Midas Information Technology Co., Ltd.

3

2

2

X-dir./ Y-dir.

IBC2012 (ASCE7-10) Basic Wind Speed : 85 mile/h Exposure Category : C Directional Factor : 0.85 Gust Effect Factor : 0.85

X-dir./ Y-dir.

IBC2012 (ASCE7-10) Site Class : D Importance Factor : 1.0 Response Modification Coefficient (R) : 4.0 Maximum Period : 6.0 sec

6/49

Step

01

1-1.Opening the pre-generated model file

Automesh and slab / wall design tutorial

Procedure Open the pre-generated model file. 1 File > Open Project… 2

2 Select “flat slab.mgb”. 3

Click [Open] button.

3

Midas Information Technology Co., Ltd.

7/49

Step

01

1-2. Auto-mesh planar area (1)

Automesh and slab / wall design tutorial

Procedure 7

Generate meshed elements for slabs Specify meshed area for automeshing (Line elements method).

1 Model > Mesh > Auto-mesh Planar Area

8 2 3

2 Method : Line Elements 3 Type : Quad + Triangle 4 Mesh Size : Length : 0.5 m

4

5 Material : 1:Grade C4000 Thickness : 1:0.2000

5

9

6 Domain : 1 6

7 Select “Select by Plane” 10

8 Select “XY Plane” 9

Click edge of the ‘Roof’ to select ‘Roof’ as a picture Iso View

10 Click [Apply] Midas Information Technology Co., Ltd.

8/49

Step

01

1-2. Auto-mesh planar area (2) Procedure

Generate meshed elements for walls Specify meshed area for automeshing (Line elements method).

Automesh and slab / wall design tutorial

4 1

1 Click > “Select elements by identify” 2 Select “Wall” > [Add] 2 3 Click [Close] 4 Click [Activation]

3

> [Activate]

Midas Information Technology Co., Ltd.

9/49

Step

01

1-2. Auto-mesh planar area (3)

Automesh and slab / wall design tutorial

Procedure Generate meshed elements with opening Specify meshed area for automeshing (Nodes method).

2

1 Model > User Coordinate System > X-Z Plan 2 Origin : 39, 4, 0 Click : [Apply] > [Close] 3 Model > Grids > Define Point Grids

4

4 dx, dy : 1, 1 Click : [Apply] > [Close]

Midas Information Technology Co., Ltd.

10/49

Step

01

1-2. Auto-mesh planar area (4)

Automesh and slab / wall design tutorial

Procedure Generate meshed elements for walls Specify meshed area for automeshing (Line elements method).

1 Model > Mesh >

Auto-mesh Planar Area

1 2 4

2 Method : Nodes 3 Draw as a picture below. 5 4 Type : Quadrilateral 6 5 Mesh Size : Length : 0.5 m 7 6 Material : 2:Grade C4500 Thickness : 2:0.2500

8

7 3

7 Domain >Name : ‘2’ 8 Click [Apply] > [Close]

4 8

6

3

5 2

9 1 Midas Information Technology Co., Ltd.

11/49

Step

01

1-2. Auto-mesh planar area (5) Procedure

Automesh and slab / wall design tutorial

3

Generate meshed elements for walls Specify meshed area for automeshing (Line elements method).

1 Model > Mesh > Auto-mesh Planar Area

1 2

Method : Planar Elements 4

2 Type : Quadrilateral Mesh Size : Length : 0.5 m Material : 2:Grade C4500 Thickness : 2:0.2500 3 Click ‘Select by window’

5

4 Select as a picture 6 5 Domain >Name : ‘3’ 6 Click [Apply]

Midas Information Technology Co., Ltd.

12/49

Step

01

1-2. Auto-mesh planar area (6) Procedure

Automesh and slab / wall design tutorial

3

Generate meshed elements for walls Specify meshed area for automeshing (Line elements method).

1 Method : Planar Elements

1 2

2 Type : Quadrilateral Mesh Size : Length : 0.5 m Material : 2:Grade C4500 Thickness : 2:0.2500 3 Click ‘Select by window’ 4 Select as a picture 4

5 5 Domain > Name : ‘4’

6

6 Click [Apply] > [Close]

Midas Information Technology Co., Ltd.

13/49

Step

02

2-1. Pressure loads (1)

Automesh and slab / wall design tutorial

Procedure

1

Apply floor loads.

2 3

1 Click ‘Activate All’ 4 2 Toggle off ‘Point Grid’ 3 Click ‘Switch to GCS’.

5 6

4 Tree Menu > Work > Domain1 [1] > Double Click 5 Load > Pressure Loads 6 Load Case Name : LL 7 Direction : Local z 7 8 Loads : P1 : -4.0kN/m2 9 Click [Apply] > [Close]

8 9

Midas Information Technology Co., Ltd.

14/49

Step

02

2-2. Building generation

Automesh and slab / wall design tutorial

Procedure 6

1 Model > Building > Building Generation 2 2 Number of Copies : 4

3

3 Distance(Global z) : 3 m 4

4 Operations : Click [Add] 5 Check off “Copy Node Attributes” option. 6 Click [Select All] icon 7

Click [Apply]

Midas Information Technology Co., Ltd.

5 7

15/49

Step

02

2-3. Automatic generation of the story data

Automesh and slab / wall design tutorial

Procedure 1 Model > Building > Story 2 Click [Auto Generate Story Data] button 3 Click [OK] 4 Click [Close]

2

Midas Information Technology Co., Ltd.

4

16/49

Step

02

2-6. Wind loads

Automesh and slab / wall design tutorial

Procedure 1 Load > Lateral Loads > Wind Loads > Click [Add]

2

1

7

2 Load Case Name : WX Wind Load Code : IBC2012(ASCE7-10) 3 Wind Load Direction Factor : X-Dir. : 1, Y-Dir. : 0 4 Click [Apply] 5 Load Case Name : WY Wind Load Direction Factor :

3 5

X-Dir. : 0, Y-Dir. : 1 6 Click [OK]

6

4

7 Click [Close]

Midas Information Technology Co., Ltd.

17/49

Step

02

2-7. Response spectrum functions

Automesh and slab / wall design tutorial

Procedure 2

1 Load > Response Spectrum Analysis Data > Response

4

Spectrum Functions 3 2 Click [Add] 3 Click [Design Spectrum] 4 Design Spectrum : IBC2012(ASCE7-10) 5

Click [OK]

5 6

6 Click [OK] 7 Click [Close]

Midas Information Technology Co., Ltd.

18/49

Step

02

2-8. Response spectrum load cases

Automesh and slab / wall design tutorial

Procedure 1 Load > Response Spectrum

2 5

Analysis Data > Response Spectrum Load Cases 2 Load Cases Name : RX Excitation Angle : 0 3 3 Check : IBC2012(ASCE7-10) 4 Click [Add] 5 Load Cases Name : RY Excitation Angle : 90 > Click [Add] 4 6 Click [Eigenvalue Analysis control]

6 7

Number of Frequencies: 15 > Click [OK] 7 Click [Close]

Midas Information Technology Co., Ltd.

19/49

Step

02

2-9. Automatic generation of load combinations Procedure

Automesh and slab / wall design tutorial

3

1 Results > Combinations > Concrete Design > Auto Generation 2 Select Design Code as “ACI318-11” > Click [OK] > Click [Close] 3 Perform Analysis

1

2

Midas Information Technology Co., Ltd.

20/49

Step

03

3-1. Column design Procedure

Automesh and slab / wall design tutorial

3 5

1 Design > Concrete Design Parameter> Design Code

2

2 Select Design Code as “ACI318-11” > Click [OK] 3 Design > 4

Concrete Code Design > Column Design 4 Click [Select All] and [Update Rebar] button.

then

5 Sorted by : Member > Check the design results > click [Close]

Midas Information Technology Co., Ltd.

21/49

Step

03

3-2. Modify column rebar data

Automesh and slab / wall design tutorial

Procedure 1 1 Design > Concrete Design Parameter> Modify Column Rebar Data

2

2 Select SECT “2-1” in the list. 3 Check the rebar data. Rebar data can be modified in this dialog box.

3

4 Click [Add/Replace] > [Close]

4

Midas Information Technology Co., Ltd.

22/49

Step

04

4-1. Slab and wall load combinations

Automesh and slab / wall design tutorial

Procedure Slab/Wall Load Combination Select the load combinations for the slab/wall element design.

2

1 Design > Meshed Slab/Wall Design > Slab/Wall Load Combinations 2 Select the desired load combinati on in each column to consider dur ing the slab/wall design.

3

3 Click [OK]

Midas Information Technology Co., Ltd.

23/49

Step

04

4-2. Design criteria for rebar

Automesh and slab / wall design tutorial

Procedure Specify rebar size Enter the standard sizes of rebars used in the design of reinforcement for slab/wall elements.

1

1 Design > Meshed Slab/Wall Design > Design Criteria for Rebar 2 2 Check off [Basic Rebar for Slab]. Basic rebar option is useful when the engineer wants to assign the identical rebar to the entire slabs and checks the additional rebar amount.

3 For Slab Design : Dir. 1 : 0.03 m, 0.03 m Dir. 2 : 0.05 m, 0.05 m

3

4 Click [OK]

Midas Information Technology Co., Ltd.

24/49

Step

04

4-3. Active Identity

Automesh and slab / wall design tutorial

Procedure 1 1 View > Activities > Active Identity 2 Click : Story > ROOF

2

Check : +Below 3 Click : [Active] > [Close]

Midas Information Technology Co., Ltd.

3

25/49

Step

04

4-4. Slab flexural design (1)

Automesh and slab / wall design tutorial

Procedure Slab Flexural Design Check the flexural design results for slab elements in contour. 1 1 Design > Meshed Slab/Wall Design >

2

Slab Flexural Design

5

2 Select [Avg. Nodal]. 4 3 Check [As_req(m^2/m)] 3 4 Check on One-Way Flexure Design option and click […] button 5 Defined Cutting Lines [Add]

6

 Display the bending moments of the floor slab elements along a cutting line, and produce the design results of reinforcement.

6 Click [Apply]

Midas Information Technology Co., Ltd.

26/49

Step

04

4-4. Slab flexural design (2)

Automesh and slab / wall design tutorial

Procedure 1 Design > Meshed Slab/Wall Design >

1

Slab Flexural Design 2

2 Select [Avg. Nodal]. 3 Click [Design Result]  Produce the detail flexural design results of slab elements in a text format.

4 Click [Design Force]  Produce the flexural design forces of slab elements in a tabular format.

3 4 5

5 Click [Update Rebar]  Update the rebar quantity for each sl ab element. The updated rebar data is used for strength verification.

Midas Information Technology Co., Ltd.

27/49

Step

04

4-4. Slab flexural design (3)

Automesh and slab / wall design tutorial

Procedure 1 Design > Meshed Slab/Wall Design > Slab Flexural Design

1 3

2 Check [Resistance Ratio]

4

 The ratio of the design moment to the moment resistance when the designed rebar spacing is applied.

5

3 Load Cases/ Combinations : ALL COBMINATION 2

4 Select [Avg. Nodal]. 5 Check [Dir.1]

6

6 Click [Apply]

Midas Information Technology Co., Ltd.

28/49

Step

04

4-4. Slab flexural design (4)

Automesh and slab / wall design tutorial

For practical design, smooth moment distributions are preferred. By selecting the smoothing option, the

Procedure

program can consider the smooth moment in slab design.

[Smoothing] Design > Meshed Slab/Wall Design > Slab Flexural Design

Element: Design results are displayed using the internal forces calculated at each node of elements. (no smoothing) Avg. Nodal: Design results are displayed using the average internal nodal forces of the contiguous elements sharing the common nodes.

Element: Design results are produced for moments at each node of slab elements. (no smoothing) Width: Design result of slab elements at each node is produced using the average of the bending moments of the contiguous slab elements with the specified width.

EN92

(Example) Design force for Node. EN21 In one plate element, 4 internal forces exist. For the element E2, member forces exist at the node EN21, EN22, EN23 and EN24. Following equations show how the smoothing option works for the node EN21. (Assume that rebar direction is selected as Angle 2 for Width smoothing direction.)

Width smoothing : weighted average method b

a

v2

v3

weighted v2에 대한 average 가중평균for ‘v2’ = (v1 + v 2) × a / 2 + (v3 + v 2) × b / 2 a+b

Midas Information Technology Co., Ltd.

EN102

EN111

N8

EN112

EN121

N9

EN72

EN83

EN82 N1

N2

N3

(1) Element + Element: EN21 2m (2) Avg. Nodal +Element: (EN12+EN21+EN33+EN44)/4 1 (3) Element + Width 2m (dir. 1): {(EN21+EN92)*1m/2+(EN21+EN101)*1m/2+(EN21+EN73)*1m/2+(EN21+EN14)*1m/2 2

v1

EN101

N7 EN73

EN133

EN144

EN143

EN144

EN143

EN154

+(EN21+EN72)*1m/2+(EN21+EN11)*1m/2+(EN21+EN83)*1m/2+(EN21+EN34)*1m/2 +(EN21+EN82)*1m/2+(EN21+EN31)*1m/2+(EN21+EN133)*1m/2+(EN21+EN144)*1m/2 +(EN21+EN112)*1m/2+(EN21+EN121)*1m/2+(EN21+EN23)*1m/2+(EN21+EN154)*1m/2 +(EN21+EN22)*1m/2+(EN21+EN151)*1m/2+(EN21+EN43)*1m/2+(EN21+EN64)*1m/2 +(EN21+EN42)*1m/2+(EN21+EN61)*1m/2+(EN21+EN143)*1m/2+(EN21+EN154)*1m/2} /(1m*24)

29/49

Step

04

4-4. Slab flexural design (5)

Automesh and slab / wall design tutorial

Procedure 1 Design > Meshed Slab/Wall Design >

1

Slab Flexural Design

3

2 Check [Wood Armer Moment]  Display the Wood Moments in contour.

Armer

4

3 Load Cases/ Combinations : ALL COBMINATION 4 Check [Dir.1] 2 5 Click [Apply] 5

Midas Information Technology Co., Ltd.

30/49

Step

04

4-4. Slab flexural design (6)

Automesh and slab / wall design tutorial

Design Strength ≥ Required Strength

Procedure [Design strength of

Φ(Nominal Strength) ≥ U

flexural member]

1. Design Strength

Flexural strength of meshed slab is calculated based on the doubly reinforced beam design method.

M n1 As ‘ f y (d − d ‘) Doubly Reinforced:= a M n2 = ( As − As ‘) f y (d − ) 2

where, a =

( As − As ‘) f y 0.85 f ck b

a ΦM n = Φ ( M n1 − M n 2 ) = Φ[ As ‘ f y (d − d ‘) + ( As − As ‘) f y (d − ) 2

Cross Section

Midas Information Technology Co., Ltd.

Strain

Strength

31/49

Step

04

4-4. Slab flexural design (7) Procedure

[Design strength of flexural member]

Automesh and slab / wall design tutorial

Design Strength ≥ Required Strength Φ(Nominal Strength) ≥ U

2.Strength reduction factor Strength reduction factor needs to be calculated based on the tensile strain in extreme tension steel.

Strength reduction factor is uniformly applied as 0.9 in midas Gen.

Midas Information Technology Co., Ltd.

32/49

Step

04

4-4. Slab flexural design (8)

Automesh and slab / wall design tutorial

Procedure [Design strength of flexural member] 3. Minimum reinforcement of flexural members

As ,min = 0.002bh

for f y = 40ksi or 50ksi

As ,min = 0.0018bh

for f y = 60ksi

As ,min =

0.0018 × 60000 bh fy

for f y > 60ksi

Above limitation is applied in midas Gen. If fy > 60ksi, As,min is the smaller of 0.0014 and

0.0018 × 60000 bh . fy

4. Maximum reinforcement of flexural members

In midas Gen, maximum rebar ratio is limited as 75% of balanced rebar ratio as per Appendix B10.3.3. 5. Minimum Spacing Limit Rebar spacing shall not be less than the smaller of “3*slab thickness” and 18in.

Midas Information Technology Co., Ltd.

33/49

Step

04

4-4. Slab flexural design (9)

Automesh and slab / wall design tutorial

Procedure [Wood Armer Moment]

6. Required Moment Strength calculated from Wood Armer moment From the analysis results, following plate forces about the local axis are calculated – mxx – myy – mxy In order to calculate design forces in the reinforcement direction, angle α and φ will be taken as following figure:

x, y: local axis of plate element 1, 2: reinforcement direction α: angle between local x-direction and reinforcement direction 1 φ: angle between reinforcement direction 1 and reinforcement direction 2

Firstly, internal forces (mxx, myy and mxy) are transformed into the a-b coordinate system.

Midas Information Technology Co., Ltd.

34/49

Step

04

4-4. Slab flexural design (10)

Automesh and slab / wall design tutorial

Procedure [Wood Armer Moment]

Then, Wood-Armer moments are calculated as follows:

Midas Information Technology Co., Ltd.

35/49

Step

04

4-5. Slab shear checking (1)

Automesh and slab / wall design tutorial

Procedure Slab Shear Checking Produce the two-way shear (punching shear) check results at the supports of slab elements or at concentrated loads and the oneway shear check results along the user-defined Shear Check Lines.

1

1 Design > Meshed Slab/Wall Design > Slab Shear Checking 2 2 Click [Design Result]

3

Produce the detail punching shear design results of slab elements in a text format. If the plate elements of a certain critical perimeter are selected in the model view, the detail results will include the punching shear results of the selected elements. If none of the element has been selected, the most critical results will be plotted in the detail result text output.

3 Click [Apply]

Code Method Midas Information Technology Co., Ltd.

FEM Method 36/49

Step

04

4-5. Slab shear checking (2) Procedure

[Shear strength] [Punching Shear Check(By CODE)]

ΦVn ≥ Vu

Automesh and slab / wall design tutorial

Where, Vc : nominal shear strength provided by concrete Vs : nominal shear strength provided by shear reinforcement

Vn = Vc + Vs

Shear strength reduction factor is applied as 0.75.

1. Shear strength of Concrete, Vc   4  Φ  2 +  λ f ck β     αd Vc= min Φ  2 + s  λ f ck bo     Φ 4λ f ck   where,

β: Ratio of the maximum to the minimum dimension of a column or wall bo: Critical perimeter αs : 40(Interior column), 30(Edge column), 20(Corner column) λ: 1.0 (normal weight concrete)

Midas Information Technology Co., Ltd.

37/49

Step

04

4-5. Slab shear checking (3)

Automesh and slab / wall design tutorial

Procedure [Punching Shear Check(By CODE)]

Punching shear perimeter for calculating concrete shear strength

In this method, the program takes the axial force in the column supporting the slab as the shear force (V u). The basic control perimeter is taken at a distance d/2 from the column face (as shown in the diagram below).

Maximum Shear Strength by Concrete (ACI318-11 11.1.3.1)

Vn ≤ 6 f ck bo d Vc ≤ 2λ f ck bo d In midas Gen, the above limitation is applied when slab thickness is larger than 200mm.

Midas Information Technology Co., Ltd.

38/49

Step

04

4-5. Slab shear checking (4)

Automesh and slab / wall design tutorial

Procedure [Punching Shear Check(By CODE)]

2. Shear strength of reinforcement, Vs Vs =

Av f y d s

Vs ,min = 4 f ck bw d Shear rebar spacing limit

s ≤ 0.5d 0.75d s≤ 0.50d

for ν u ≤ 6φλ f ck for ν u > 6φλ f ck

g ≤ 2d Minimum Shear Rebar Area

1 φVc
bw s fy

but shall not be less than (50bw s ) / f y .

In midas Gen, required rebar area is calculated by “Vs = Vn- Vc”. Shear rebar spacing limit and minimum shear rebar area are not applied. Midas Information Technology Co., Ltd.

39/49

Step

04

4-5. Slab shear checking (5)

Automesh and slab / wall design tutorial

Procedure [Punching Shear Check(By CODE)]

3. Required Shear Strength, Vu Case A. Exterior column

Case B. Interior column

Unbalanced moment between a slab and column by flexure

γ v= (1 − γ f ) Unbalanced moment between a slab and column by eccentricity of shear

γf =

1 1 + (2 / 3) b1 / b2

Factored shear stress

v f ( AB= )

Vu γ v M u c AB + Ac Jc

v f (CD= )

Vu γ v M u c AB − Ac Jc

Midas Information Technology Co., Ltd.

Case C. Exterior column

Case D. Conner column

40/49

Step

04

4-5. Slab shear checking (6)

Automesh and slab / wall design tutorial

Procedure [Punching Shear Check(By FEM)]

In these methods (The FEM Method), the Shear force along the critical section is taken and divided by the effective depth to calculate shear stress. Therefore there is no need to calculate β (Beta), to consider moment transferred to the column.

(There are 4 plate elements intersecting at nodes. The nodes are marked by nomenclature of Grid Lines. As the center node is denoted by B2 , B on x-Axis and 2 on Y-Axis) When slab is defined as the plate element, the program calculated stresses only at the nodes, in the analysis. So we have the stresses at B1, B2, C2 etc. (see the figure above) are calculated by the program. Case 1 – To calculate stresses at the critical section that is u1 in the given figure, for example we take the point P in the figure which lies in a straight line. The stress at B1 and B2 are known. The values at these nodes are interpolated linearly to find the stress at point P . Case 2- Now if the point lies in the curve such as the point Q, then the software will divide the curve into 6 parts. At each point such as Q a tangent which intersects B1-B2 and C2-B2.The value of stresses at T and V are determined by linear interpolation of stresses which are known at for T (at B1 and B2) and for V (at C2 and B2). After knowing stresses at T and V the stress at Q is determined by linear interpolation of stresses at T and V.

Midas Information Technology Co., Ltd.

41/49

Step

04

4-5. Slab shear checking (7) Procedure

[Punching Shear Check(By FEM)]

Automesh and slab / wall design tutorial

(Method 1: Average by elements.) In this method the stresses at all the critical points is determined. The critical points divide the critical section into segments. The average value for all these segments is determined by dividing the stresses at the two ends of the segment by 2. After determining the average value for each segment, the maximum average value from all of the segments is reported as the Stress value for the critical Section.

a,b are stresses at the segment ends. Average value for the segment will be (a+b)/2, and such average value for each segment is determined.

Midas Information Technology Co., Ltd.

42/49

Step

04

4-5. Slab shear checking (8) Procedure

[Punching Shear Check(By FEM)]

Automesh and slab / wall design tutorial

(Method 2: Average by Side) In this method stresses at all critical points is determined and then average stress value is calculated by weighted mean. To calculate weighted mean , For example we have 4 critical points a, b, c, d.

– Stress at critical points: For example at ‘a’ its 9 – Average of the segment: For example in ‘a’ and ‘b’ its (15+9)/2 = 12 – Distance Between the critical points: For example between ‘a’ and ‘b’ its 8 – Final Stress = (12 * 8 + 17 * 10 + 15 * 6)/ (8+10+6), which is the weighted average.

We divide the Critical section into 4 sides as shown in figure. The weighted mean value for each side is determined and then the maximum value out of the 4 sides A, B, C, D is reported as the stress value.

Midas Information Technology Co., Ltd.

43/49

Step

04

4-6. Serviceability parameter Procedure

Automesh and slab / wall design tutorial

Slab deflection is verified as per the clause 9.5.3 of ACI318-11. This deflection limit can be entered by the user in Serviceability Parameter.

1 Design > Concrete Design Parameter > 2

Serviceability Parameter 2 Select All

4

1

3 Click [Apply] 4 Unselect All 3

Midas Information Technology Co., Ltd.

44/49

Step

04

4-7. Slab serviceability checking

Automesh and slab / wall design tutorial

Procedure 1 Design > Meshed Slab/Wall Design >

1

Slab Serviceability Checking 2 Check [Uncracked] and [Creep]. Calculate the deflection for the uncracked section and compare it with the allowable deflection. Deflection for the cracked section is not supported in the current version.

3 Select [Ratio]

2 3 4 5

4 Click [Detail Result] 5 Click [Apply]

Midas Information Technology Co., Ltd.

45/49

Step

04

4-8. Wall design (1)

Automesh and slab / wall design tutorial

Procedure Wall Design Wall design forces and tension reinforcements are obtained in an element subject to in-plane orthogonal stress. The tension reinforcement in an element subject to in-plane orthogonal stresses σEdx, σEdy and τEdxy can be calculated as shown below. Compressive stresses should be taken as positive, with σEdx > σEdy, and the direction of reinforcement should coincide with the x and y axes.

where, ρx and ρy are the geometric reinforcement ratios, along the x and y axes respectively. In locations where σEdy is tensile or σEdx ⋅ σEdy ≤ τ2Edxy, reinforcement is required. The optimum reinforcement, indicated by superscript ′, and related concrete stress are determined by:

Wall design using wall element is also supported in midas Gen. Reference: Nielsen, M.P., Limit Analysis and Concrete Plasticity, Second Edition, CRC Press, USA, 1999 Midas Information Technology Co., Ltd.

46/49

Step

04

4-8. Wall design (2)

Automesh and slab / wall design tutorial

Procedure Wall Design Minimum reinforcement for vertical and horizontal rebar is considered in accordance to ACI318-11, 14.3.2 and 14.3.3. Maximum ratio of of vertical reinforcement are applied as “0.04” and it can be modified in Design > Concrete Design Parameter > Limiting Maximum rebar Ratio. [Minimum ratio of vertical reinforcement area]

[Maximum ratio of vertical reinforcement area] 0.04

[Minimum ratio of horizontal reinforcement area]

Midas Information Technology Co., Ltd.

47/45

Step

04

4-8. Wall design (3)

Automesh and slab / wall design tutorial

Procedure Wall Design Perform the flexural design results for wall elements in contour.

1 2

 Wall design is performed based on ACI318-11.

3

1 View > Activities > Active All 2 Design >

4

Meshed Slab/Wall Design > Wall Design  Display the area of required reinforcement.

5 the

Check [As_req(m^2/m)] 3 Select [Avg. Nodal] 4 Select [Resistance Ratio] 5 Click [Apply]

Midas Information Technology Co., Ltd.

48/49

Step

04

4-8. Wall design (4)

Automesh and slab / wall design tutorial

Procedure 1 Design > Meshed Slab/Wall Design > Wall Design

1

2 Click [Design Result] 3 Click [Design Force]

2 3

Midas Information Technology Co., Ltd.

49/49