Analysis & Design of RCC shear walls in the model using ETABS

The etabs file for a G+6 building is provided. Run the analysis and design the RCC shear walls (show in the etabs model). The following challenge deals specifically with the shear wall of size 300x1500 at grid A-11 in the structural model.

AIM TO ;

• Extract values of longitudinal steel ratio, boundary element length and shear reinforcing ratio from the design results.
• Provide cross sectional steel arrangement of the shear wall from its base up to terrace, in compliance with provisions of IS 13920 – 2016. AutoCAD application can be used for this exercise. Alternatively, it can be drawn by hand as well.
• Provide elevation drawings of the reinforcement details of the shear wall from base up to terrac

 

 

 shear reinforcement in the wall 

required 750mm2

 boundry element width IN THE LOWER PART.

bottom left    600mm

bottom right  450mm

 

 as per clause 10.4.1 is13920 -2016

if compressive stress > 0.2fck boundry element required

                                 0.2x25 = 5

 Boundry element not required after 2nd floor

 

fixed support

EQX

EQY

MAX STORY DRIFT

EQX

EQY

PINNED SUPPORT

MAX STORY DRIFT

EQY

 slender

	tw	Lw		height	type of wall	Ph (MIN)	Pv (min)	Pv (min)	Pv (web)
footing to ground	350	1200		21000	slender
ground to first floor	350	1200		21000	slender
first to 2nd	350	1200		21000	slender
2nd to 3rd	350	1200		21000	slender
3rd to 4th	350	1200		21000	slender
4th to 5th floor	350	1200		21000	slender

   Reinforcement details for shear wall

GIVEN DATA ;tw= 300mm, Hw= 21000mm,Lw=1500mm,

As the wall is slender = Hw/Lw > 2

                                        21000/1500= 14 >2 ,wall is design as slender

As per clause 10.1.6, table 1

Ph=minimum horizontal reinforcement= 0.0025+0.5(Hw/Lw -2)(ph-0.0025)

Ph= .0025+.5(21000/1500-2)750/300x1000-.0025= .0025

Pv(BE)= minimum vertical reinforcement in boundry element =0.0080

                     .0080X300X1500=3600MM2

Pv(WEB)= minimum vertical reinforcement in web=0.0025

                     .0025X300X1500=1125MM2     

Pv(net)= net minimum vertical reinforcement =0.0025+.01375(tw/lw)

                .0025+.01375(300/1500)x300x1500=2363mm2

Maximum dia of shear wwall as per clause 10.1.8

1/10^th of wall thickness ~ 300/10= 30mm

NOW CALCULATION OF WEB STEEL

MINIMUM VERTICAL REINFORCEMENT IN WEB Av (mm2) = 0.0025X300X1500= 1125mm2

Minimum spacing required as per clause 10.1.9

1/5^th of horizontal length

3 times of thickeness and 450mm which ever is less

Choose the spacing 200 to 250  

Assume t10

Boundry elemnent length at

Foundation to ground = 600mm( left) and 450mm( right)

ground to 1^st =               450mm                    300mm

1^st to 2^nd  =                     300mm                    300mm

2^nd to 3rd=                     300mm                    300

3^rd to 4^th=                        300                            300

4^th to 5^th=                      300                             300

5^th to terrace=                 300                         300

Minimum vertical steel provided in boundry element;

0.0080x600x300=1440 mm2 at left side

0.0080x450x300=1080 mm2 at right side

Area of longitudinal steel reqired as per floor wise in etab result

Fonudt to ground

Ground to first

1^st to 2^nd

2^nd to 3^{rd=          2577mm2}    

3^rd to 4^{th=          2154mm2}

4^th to 5^{th=            2150}      

5^th to terrace= 2150mm2

Shear reinforcement required as per floor wise in etab

                      =750mm2 in all floor

Confining reinforcement i.e shear reinforcement in boundry element

As per clause 10.4.4

Ash= 0.5.sv . h.fck/fy

And spacing should not be more than

1/3^rd of minimum member dimension of boundary element

6 times dia of longitudinal steel in BE ,and  100mm

Area of longitudinal steel required by etabs= 13399mm2

Vertical steel should be less than 30mm

Area of 25 mm= 490mm2 =28bar so provide 14no at one line and 14 another line

Area of 20mm = 314mm2=42.6

Area of 16 mm=201mm2=66

Ash=0.05xSvxhxFck/Fy

        Ash= .05x100x1000x30/500

               300mm2/m

so provide 28# 25mm@160MM VERTICAL

for shear reinforcement

Ash=750 mm2

Assume 2 legged  8mm c/c@100mm