Koto multi level manual 7 3 2013

MULTI-LEVEL WALLING MANUAL

KOTO

©™

CONTENTS E Page 1

INTRODUCTION

…2

2

THE 200 KOTO PANEL

…2

3

CONSTRUCTION

…3

4

DESIGN APPLICATION

…6

5

LOADS

...7

6

7

5.1

Vertical Loads

...7

5.2

Wind Loads

…7

5.3

Earthquake Loads

…7

DESIGN PROPERTIES

...8

6.1

Material Properties

...8

6.2

Compression Strength

...8

6.3

Moment Capacity

...9

6.4

Shear Capacity

...10

6.5

Racking Resistance

...11

DESIGN PROCEEDURE

...12

7.1

Compression

…12

7.2

Racking

...12

8

ENLARGED COLUMN

…13

9

DESIGN EXAMPLE

...16

9.1

Vertical Load

…16

9.2

Wind Load

…17

Date of issue : 7 March 2013 This manual has been prepared by Ron Marshall B.E., M.Eng.Sc. on behalf of Koto Corp for use by Building Designers. The information provided in this publication is intended as general guidance only and is not a substitute for the services of professional consultants on particular projects. The manual is subject to regular updates and designers should check they have the latest version.

1 Contact email: globalsolutions@kotocorp.com

1:- INTRODUCTION This design manual has been prepared for guidance in the design of reinforced concrete columns using KOTO’s 200 permanent formwork.

While the structural system is that of column and beam, the KOTO panels fill between the columns and the columns together with the infill also serve to function as a wall. In this manual, the use of the term “wall” is taken to mean a line of closely spaced columns.

While KOTO panels are suitable for use in all buildings, the design tables included in this manual are for the blocks specifically made for multi-story residential buildings with floor to ceiling height of up to 3.6m. For single story housing refer to Kato’s Single- Story Housing Manual.

KOTO Floor Panel permanent formwork is also available for the floor slabs and is the preferred compliment to the KOTO walls. Refer to KOTO’s Flooring Manual for details

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2:-

KOTO’s 200 PANEL

KOTO’s 200 Panel is a 200mm thick panel of light weight material with precision formed 100mm by 100mm cores at 200mm centers, and pre-coated with fibre-mesh composite coating. Concrete columns are formed by reinforcing and concrete filling the cores.

KOTO 200 PANEL

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3:-

CONSTRUCTION

The buildings are constructed in the following way: 1. Foundation slab is poured with starter bars cast in to align with the centre of the cores in the KOTO Panels.

2. KOTO Panels are placed over the starter bars and glued in place.

3. Subsequent panels are glued as they are placed.

4. Vertical reinforcement is placed into the cores so that it laps with the starter bars at the bottom and extends into the slab above.

5. A horizontal bar is placed in lintels and any bond beams.

6. Columns are concreted.

7. The next floor slab is formed and cast.

Column and Slab Layout

4

Elevation

Section

Standard 100 x 100 Column details

5

4:- DESIGN APPLICATION The designs in this manual have been carried out on the basis of the following:a. Foundation and floors has sufficient strength and stiffness to provide lateral support and rotational restraint to the columns. b. Roof and floors have adequate stiffness to distribute the racking forces to the columns. c. Starter bars extending from the floors to provide anchorage at the bottom of the columns. d. Cores are reinforced. e. Column reinforcement extends into the slabs at the top to provide anchorage at the top of the columns. f. Cores are concreted to form columns. g. The columns all act together to carry the vertical loads from above and to resist lateral loads imposed on the building. h. The floors act as beams between the columns. i. Where the roof is not a concrete slab, then a bond beam must be used to connect all the columns together and to connect the roof to the walls.

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5:- DESIGN LOADS 5.1 Vertical loads The imposed and permanent loads are obtained from the appropriate sections of the loading codes. For limit state design load factors are applied.

5.2 Wind Loads The wind pressure is derived from the wind speed appropriate for the location, building height and terrain, multiplied by the Pressure coefficient for the building element. Hence the wind pressures can vary for every building.

For Malaysia, the base wind speed is 33.5 m/s inland and 32.5 m/s on the coastal strip. Using Appendix A – Simplified procedure – Malaysian Standard MS 1553:2002 Code of practice on wind loading for building structure, the Terrain/height multiplier can be taken as 0.91 for buildings up to 5m high, 1.00 up to 10m high and 1.08 up to 20m high and the pressure coefficient used for calculating the racking forces on a building is 1.3. Using these factors, and applying a load factor of 1.4, the design pressures are as shown in TABLE 5.1 TABLE 5.1 Design wind pressure for Malaysia Basic wind speed**

Building Terrainheight height multiplier up to

Building Base Design wind pressure design wind with pressure coefficient wind pressure Cpe-Cpi =1.3 speed** (m/s) (m) (m/s) (kPa) (kPa) 5 0.91 29.5 0.53* 1.18 32.5 10 1.00 32.5 0.65 1.18 Zone ll 20 1.08 35.1 0.75 1.36 5 0.91 30.5 0.57* 1.18 33.5 10 1.00 33.5 0.69 1.25 Zone l 20 1.08 36.2 0.80 1.46 Note: * Minimum base wind pressure taken for design is 0.65 kPa ** For other locations the designer will need to establish the wind speed appropriate to that location

5.3 Earthquake Loads In low earthquake areas the racking forces from earthquake will be less than that from wind loads and hence may be ignored. In high earthquake areas, because of the light weight nature of a KOTO building, the racking forces from earthquake will generally still be less than that from wind, but these loads also will need to be calculated and the columns checked.

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6:- DESIGN PROPERTIES 6.1 Material Properties The design tables in this manual are based on materials with the following properties:  

6.2

Mass of fully concreted KOTO wall Characteristic Compressive Strength of concrete Yield Strength of “Y” bar reinforcement

w = 1.8 kN/m2 fcu = 30 MPa f y = 460 MPa

Compressive Strength

The compressive strength of the columns is calculated in accordance with BS8110 Section 3.8 Columns. Clause 3.8.1.4 Plain concrete columns states “If a column has a large enough section to resist the ultimate loads without the addition of reinforcement, then it may be designed similar to a plain concrete wall”. Because KOTO columns are designed for compression ignoring the reinforcement then Section 3.9 Walls has been use as the appropriate calculation approach. In particular Clause 3.9.4.16 Maximum design ultimate axial load for slender braced plain walls has been used.

The design ultimate axial load capacity is calculated using the formula for compressive strength of walls from Clause 3.9.4.16 as follows:-

nw  0.3 (h  1.2 ex  2 ea ) f cu The value of ex for walls with slabs on both sides (concentric load) is taken as h/20 and for external walls with slab on one side only as h/6 (load at middle third point).

2

The value ea is taken as le /2500h where le is 0.75 times the height between slabs.

The axial load capacity for the KOTO 100 by 100 columns using 30 MPa concrete is given in TABLE 6.1 For concrete strengths other than 30 MPa the load capacity is proportional to the concrete strength.

TABLE 6.1 Compressive strength of columns

Column detail

Wall height (mm)

Ultimate axial load Capacity (kN/column) External wall

Internal wall

2400

48

61

2700

42

55

3000

35

48

3600

20

32

8

9

6.3 Moment Capacity For resistance to lateral loads, the columns act as vertical beams and are checked as beams for both flexural and shear strength.

The moment capacity of columns have been calculated using the formula below which is derived from BS 8110-1:1997- Figure 3.3 - Simplified stress block for concrete at ultimate limit state

Moment Capacity

fy   0.75 Ast fy m  M Ast d 1  f cu m bd   m 

     

TABLE 6.2 Moment capacity of columns

Column type

Moment capacity of column (kNm)

1.16

10

6.4 Shear Strength The shear strength of columns have been calculated in accordance with Clause 3.4.5 – Design shear resistance of beams, Table 3.7 as follows:1

1

1

 100 As f cu  3  400  4  f cu  2   0.79     b d 25  d   25  v   vc 

Design Concrete Shear Stress:-

m

Asvmin 

Minimum Shear reinforcement (if provided):-

0.4 bv sv 0.95 f yv

Design Shear Stress:-when shear reinforcement is not provided -when shear reinforcement is provided

v  0.5vc v  (vc  0.4)

Design Shear Capacity

V  vbv d

where

bv = Width of web d = Distance from compression face to tensile reinforcement For a 100x100 beam without shear reinforcement 1

1

1

 100 *113 30  3  400  4  30  2 0.79      100 * 50 25   50   25   vc   1.62 MPa 1.25 V  vbv d 0.5 *1.62 *100 * 50 *103  4.0 kN / column

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6.5

Racking Capacity

The racking capacity is the lesser of the resistance in flexure and resistance in shear strength. NOTE: as the KOTO columns are square with a central reinforcing bar, the racking strength is the same in both directions.

The resistance in flexure is the result of the columns acting as vertical beams rotationally restrained at the base and top by the floors and calculated by equating the imposed racking loads to the resisting moments-

The racking resistance in shear is simply the shear strength of the column The racking values are as given in TABLE 6.2. Note: no account has been taken of compression on the columns and are hence the values are conservative for lower floors of a building.

TABLE 6.2 Racking capacity of columns Column detail

Racking strength in shear (kN/column)

Column height (mm) 2400

Racking strength in flexure (kN/column) 0.97

4.0

2700

0.86

3000

0.78

3600

0.65

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7:- DESIGN PROCEEDURE 7.1 Compression The vertical load on a wall is the total dead and imposed load (with the appropriate load factors applied) that is carried by that wall. The compressive strength of the columns within that wall is checked to ensure that it is higher than the applied loads.

It is usually necessary to only check the most heavily loaded wall to each floor level.

7.2 Racking The Racking load on a building is the wind pressure multiplied by the effective exposed area. The effective exposed area can be taken as the building width times the height from the centre of the story under consideration to the top of the building.

As the columns have equal stiffness in both directions, the racking is resisted by all the columns (in both the longitudinal and the cross direction), acting together. The racking resistance of the building is determined by multiplying the number of columns at the story under consideration by their strength.

Step 1 Determine the wind pressure on the building. The wind pressure will vary at different heights up the building but it is usual to just take with highest pressure (which will be at the top of the building) and use it on all the building.

Step 2 Determine the exposed area at the relevant level and calculate the applied racking force at that level. Check for wind in the direction of the longest wall. It is only necessary to check the direction with the greatest lateral load as all the columns are acting together and have the same strength in both directions.

Step 3 Add up the total number of columns at that level and multiply by the racking resistance of each column (from table 6.2) to determine the total racking resistance.

Step 4 Check whether the total resistance exceeds the applied racking force.

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8:- ENLARGED COLUMNS In all but unusual situations the standard columns are all that will be necessary. If in the event that extra strengthening were desired then larger columns can be made by cutting out a web of the KOTO panel between cores leaving either a 300mm by 100mm core or a 300mm by 300mm L shaped core. Two or three rods, either Y12 or Y16, tied with 6mm stirrups @ 200mm crs are then used as reinforcement.

Column Reinforcement

300 x 100 Column

300 x 300 Column

Enlarged Column Details

14

TABLE 8.1 Extended column compressive capacity Column Column Type height (mm)

Compressive capacity (kN per column) External Internal Wall Wall

2400

146

183

2700

127

165

3000

106

144

3600

58

96

2400

300

340

2700

290

330

3000

270

310

3600

240

280

15

TABLE 8.2 Enlarged column racking capacity

Column Type

Racking in Shear (kN per column) Y12

26

26

Y16

Column height (mm)

Racking in Flexure (kN per column) Y12

Y16

2400

9.5

15.9

2700

8.5

14.1

3000

7.6

12.7

3600

6.4

10.6

2400

9.5

15.9

2700

8.5

14.1

3000

7.6

12.7

3600

6.4

10.6

29

29

16

9:- DESIGN EXAMPLE Task is to design the KOTO columns for the following residential building in a Zone II wind area.

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9.1 Vertical Loading

Taking a 3.0m strip, calculate the load at the center of the lowest wallFloor Load

DL of Wall

LL x LF = 1.5 x 1.6 = 2.4 DL x LF = 2.7 x 1.4 = 3.8 Total = 6.2 kN/m2 = 6.2 x 3.0 = 18.6 kN / m length of wall DL x LF = 1.8 x 3.0 x 1.4 = 7.6 kN / m length of wall

Check 5th floor down Loads on floor-

Floors = 18.6 x 5 = 93 Walls = 7.6 x 4.5 = 34 TOTAL DESIGN LOAD = 127 kN/m length of wall

Columns are spaced at 200mm centers, hence there are 5 columns per m length of wall.

Design Capacity (From TABLE 6.1) = 48 kN/column Hence Design Capacity of Wall = 5 x 48 = 240 kN/m of wall >>127 applied load OK for Compression with all columns filled

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Check 4th floor down Loads on floor-

Floors = 18.6 x 4 = 74 Walls = 7.6 x 3.5 = 26 TOTAL DESIGN LOAD = 100 kN/m length of wall

Try every second column filled Columns are spaced at 400mm centers, hence there are 2.5 columns per m length of wall.

Design Capacity (From TABLE 6.1) = 48 kN/column Hence Design Capacity of Wall = 2.55 x 48 = 120 kN/m run of columns >>100 applied load OK for Compression with every second columns filled

Check 2nd floor down Loads on floor-

Floors = 18.6 x 2 = 37 Walls = 7.6 x 1.5 = 11 TOTAL DESIGN LOAD = 48 kN/m length of wall

Try every forth column filled ie columns at 800 crs Columns are spaced at 800mm centers, hence there are1.25 columns per m length of wall.

Design Capacity (From TABLE 6.1) = 48 kN/column Hence Design Capacity of Wall = 1.25 x 48 = 60 kN/m run of columns >> 48 applied load OK for Compression with every forth columns filled

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9.2 Racking due to Wind

CC Check the racking on a double unit 18m long Design Wind pressure on building up to 20m high = 1.36 kPa. The pressures will be less at the lower levels but for easy calculation 1.36 kPa is taken over the full height.

Check 5th floor down Total Racking force imposed on floor

= p x length x height = 1.36 x 18 x 16 = 392 kN

Total number of columns resisting racking

= Total length of all walls x 5 = 186m x 5 = 930 columns

Racking capacity = Capacity of each column (from TABLE 6.2) x No. of columns = 0.78 x 930 = 725 kN >> 392 kN design load Columns OK for Racking due to wind

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Check 4th floor down Total Racking force imposed on floor

Try every second column Total number of columns resisting racking

= p x length x height = 1.36 x 18 x 13 = 318 kN

= Total length of all walls x 2.5 = 186m x 2.5 = 465 columns

Racking capacity = Capacity of each column (from TABLE 6.2) x No. of columns = 0.78 x 465 = 363 kN >> 318 kN applied wind load OK for Racking with very second column filled

Check 2nd floor down Total Racking force imposed on floor

Try every forth column filled Total number of columns resisting racking

= p x length x height = 1.36 x 18 x 6 = 147 kN

= Total length of all walls x 1.25 = 232m x 1.25 = 181 columns

Racking capacity = Capacity of each column (from TABLE 6.2) x No. of columns = 0.78 x 232 = 181 kN >> 147 kN applied wind load OK for Racking with very forth column filled

Hence a satisfactory solution would be to fill every forth column on the top two floors, fill every second column on the next two stories down and fill every column on the fifth floor down. Doing this would make it necessary to ensure that the columns on the top two floor line up with those underneath.

Note the columns at all wall ends and at side of every opening would still need to be filled.

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