100 IMPORTANT TECHNICAL TERMS ABOUT REINFORCEMENT. A SUPERVISOR MUST KNOW
The Responsibility of a construction supervisor is very big in construction sites & he perform lots of activities at construction site. All the works at site is carried out according to the guidelines of a site Supervisor after site engineer and obviously A site Supervisor roles at site is great .A good Quality of work is the results of the performance of site-supervisor. So, For Any project quality his role is very important.
A supervisor Should have enough technical knowledge for the construction activities.Here we have some useful information for Site engineer and Supervisor must know about them.
In this post I’ll share 100 Important technical terms about Reinforcement.
1). Concrete Cover for Reinforcement.
We generally known it clear cover or concrete cover. Clear cover is the distance between steel Rebar surface and the nearest outer surface of concrete member.
Concrete cover can vary depending on the size and location of R.C.C member.
The value of concrete cover for various R.C.C members are given below:
Beam = 25 mm
Slab = 20 mm
Column = 40 mm
Footing = 50 mm
2). Standard Length of MS Bar.
Standard length of a deformed ( MS ) Mild steel bar is 40′ or 12 meter.
3). Required bending wire.
For binding one ton of steel reinforcement binding wire required 7 kg to 13 kg.
Diameter of MS bar for chair shouldn’t be less than 12 mm .
5). The Maximum Chair spacing should be 1.00 m (or) 1 No per 1 meter square.
6). Unite Weight of Steel bar.
diameter weight per meter :- (Formula=D^2/162)
6 mm = 0.222 Kg
8 mm = 0.395 Kg
10 mm = 0.616 Kg
12 mm = 0.888 Kg
16 mm = 1.578 Kg
20 mm = 2.466 Kg
25 mm = 3.853 Kg
32 mm = 6.313 Kg
40 mm = 9.865 Kg .
7). Weight of Steel MS Bar is calculated using formula D 2/162 where d is the diameter of steel bar in mm.
8). C/C means Center to Center Distance.
9). D L means Development Length.
10). T M T means Thermo Mechanically treated bars.
11). The transverse reinforcement provided in columns are called Ties.
12). The transverse reinforcement provided in Beams is called as Stirrups.
13). Full form of different types of bars.
T M X = Thermo Mechanically treated bars.
SD = Super Ductile bars.
H Y S D = high yield strength deformed bar.
C T D = Cold twisted bars.
14 ). Types of Steel Bars.
Mild Steel = Fe 250 N/mm 2
H Y S D = Fe 415 or Fe 500 N/ mm 2.
15). Minimum Diameter of bar in Slab is 8 mm.
16). Minimum diameter of bar in Column is 12 mm.
17). maximum diameter of steel in column is 50 mm.
18). Why cover block used in Reinforcement.
i). To maintain a Unique & specific distance between re bars & Shuttering.
ii). To protect steel reinforcement from corrosion.
iii). To provide thermal insulation for contract & Expand.
19). Deflection Means.
20). Why we use only Steel as a reinforcement.
Because of coefficient of thermal expansion.
21 ). R.C.C is affected by water because of corrosion of Reinforced bars.
22). P.C.C is not affected by the water.
23). Always use minimum 12 mm diameter of steel bars at the bottom of plinth beam.
24 ). Always use minimum 10 mm diameter of steel bars at the Top of plinth beam.
25). Minimum Size of R.C.C Column is 9’’ x 9’’ or 250 mm x 250 mm with minimum 4 bars of 12 mm steel of grade Fe 500.
26). Minimum Concrete grade in column is M 20.
27). Always use 8 mm stirrups at spacing of 150 mm center to center throughout the Column length.
28). Density of Steel is 7850 Kg/ cum.
29). Why we need Pile Foundation.
When the bearing capacity of soil is less than 24 k N/Cum.
30). What is Permissible Slump Value ?
Permissible Slump Value should be 75 + – 25 mm. (As per IS 1199).
For pump-able Concrete It should be = 100 + – 25 mm.
31). Why deformation are Provided in Steel Bar ?
i). To prevent Slipping of Bars from concrete.
ii). To increase bond strength between steel & Concrete.
32). Lungs height of steel bars.
It should not be greater than 0.004 to 0.005 times diameter of bars.
For example:- diameter of bar is 10 mm
lugs height = 0.04 x 10 = 0.4 mm.
For 32 mm diameter bar
Lugs height = o.04 x 32 = 1.28 mm.
33). Angle of steel bars should not be greater than 45 degree.
34). Fe means yield strength of bars is 500 N/Square mm.
35). Minimum Diameter of Bored cast in Situ pile is 450 mm.
36). Factor used to convert wet volume to dry volume of concrete is 1.54.
37). Development Length.
The length of steel which we required for transfer the load of one member to another that is called Development length ( L d).
38). Lap Length.
The length of steel used for transfer the load steel to steel and used for bonding of two steel.
39). Development length ( L d) depends upon.
i). Grades of steel Fe 415, 500, 500 d, 600
ii). Depends on grades of concrete.
40). The distance between two lapping in different bars should not be less than 1.3 meter or 1300 mm from center of lapping or not less than 13 times.
41). In case of higher or lesser diameter of bars always consider less diameter bar for lapping length.
42). Always tilt bar when lapping of two bars.
43). The limit of tilting of bar is 75 mm or 6 d.
44). Exterior Area of building is called :- Plinth Area.
45). Minimum Longitudinal Bar in a Column ?
A square-shape column should 4 numbers of bars.
and, A round Shape column should have minimum 6 numbers of bar.
46). Minimum diameter used for dowels bars should be 12 mm.
47). Why we provide Steel in Concrete ?
The tensile strength and strain capacities of concrete is very brittle ; hence, We used Reinforcement to balance this deficiency.
48). Binding Wire ?
The binding wire is use to tie the steel bars at every intersection with two strands (wire) of annealed steel wire having diameter of 0.9 to 1.6 mm thickness.
49). Reinforcement Steel Bars.
Steel Reinforcement is commonly known as ‘rebars’. And we provide the steel bars in concrete for R.C.C structure Tensile strength.
50). Important IS Code.
51). Percentage of steel in structural members.
i). Slab – 1 % of the total volume of concrete.
ii). Beam – 2 % of the total volume of concrete.
iii). Column – 2.5 % of the total volume of concrete.
iv). Footings – 0.8 % of the total volume of concrete.
52). Thumb Rule for steel quantity required for slab, Beams, Footings & Columns.
Steel required in Residential buildings = 4.5 Kg – 4.75 Kg / Sq.Ft.
Steel required for Commercial building = 5.0 kg – 5.50 Kg/Sq. ft.
53). As per Area Maximum Reinforcement.
Beam & Slab = 4 % of Gross Area.
Column = 6 % of Gross Area.
54). Young Modulus of steel.
Es = 2 x 10 ^5 N / mm.
55). Strength of Reinforcement should not be less than 15 %. Of its designated strength.
56). Developing length should be provided in Plinth and top Beam.
55). Rolled Steel Sections are Classified into five types.
I). IS : 226 ( Standard Quality ).
ii). IS : 2092 ( Fusion Welding ).
iii). IS : 961 ( High tensile steel ).
iv). IS : 1977 ( Ordinary Steel ).
v). IS : 8500 ( Medium & high Strength qualities ).
56 ). Carbon Percentage in Steel.
57). Minimum Reinforcement in different R.C.C members.
i). Beam = 0.85 x b d /f y.
ii). Column = 0.8 % of total gross area.
iii). Slab = 0.15 % of gross area ( For Fe 250 )
= 0.12 % of gross area ( For f e 450 / 500 ).
58). 1 M LENGTH STEEL ROD I ITS VOLUME.
V = (Pi/4) x Diameter x Diameter X L
= (3.14 / 4)x d x d X 1 (for 1 meter length)
Density of Steel = 7850 kg / cubic meter
Weight = Volume x Density
= (3.14 / 4) x 2 D X 1 x 7850 (if D is in mm )
So, = ((3.14/4) x D x D X
59). Placing 1st Stirrup.
The 1st stirrup of beam must be placed within 2″ from the support.
60). No. of Stirrups.
= (clear span/ c /c Spanning) + 1.
61). Minimum “L” for column main rod in footing is 300 mm.
62). Longitudinal reinforcement should not be less than 0.8% and more than 6% of gross C/S ( cross-sectional areas) of column.
63). All Reinforcement used should be free from mill scales, loose rust & coats of paints, oil or any other substances.
64). For Cantilever main steel anchorage length is 69 D.
65). As per IS 456: 2000,
Maximum diameter of Steel bar used in the slab should not be exceed 1/8th of the total Slab thickness.
66). Main bars in the slabs shall not be less than 8 mm (H Y S D) or 10 mm (Plain bars).
67). Distribution bars Should not be less than 8 mm and not more than 1/8 of slab thickness.
68). Lap length for M 20 concrete ?
Columns – 45 d.
Beams – 60 d.
Slabs – 60 d.
69). Lapping Bars Should be Provided at the end of the support.
70). Lapping should be closely spaced at lapping zone.
71). Lapping should be done in middle 3rd position of the beam.
72). Never provide lapping in the center of beam & Column.
73). Lapping of bars should be alternate in beam.
74). For lap length of slab always take 60 d , where d is diameter of bar.
75). Lapping length should not be less than 75 mm. as per IS Code 456 – 2000.
76). Maximum Lap in a Zone.
More than 50% of bars shouldn’t be lapped in one zone.
Don’t use more than 50% lapping zone in any R.C.C structure.
77). Lap in Tension.
No lapping should be placed in tension zone.
78). Lap in compression zone.
Steel should be lapping for compression zone with 50 d where ( d ) is diameter of steel bar.
79). Lapping for Tension.
Steel should be lapping for tension zone with 40 d where ( d ) is diameter of steel bar.
80). Lapping is not allowed for the bars .
Lapping or Lap slices of bars not allowed having diameters more than 36 mm.
81). Bent Up bar.
Always Provide bent up bar near at support of slab and beam.
82). Thermal expansion is the Prime reason for using steel as reinforcement in R.C.C because the thermal expansion coefficient of concrete and steel is (approximately) same having value 12 x 10−6/°C.
83). To handle the shear force and to keep longitudinal bars in position Stirrups in Beams and Ties in Column are provided.
84). Cantilever Beam has One fixed support and the other end is free, Simply supported beam has a minimum of two supports which is fixed support.
85). Spacing Of Reinforcement.
For Column : – Minimum from following :-
i). Least lateral dimensions.
ii). 16 x diameter of bar.
iii). 300 mm.
86). In case of Spacing of bars.
Provide the diameter of the bar, if the diameter of the bar are equal.
Provide the diameter of the larger bar, if the diameter are unequal.
5 mm more than the nominal maximum size of the coarse aggregate.
87). Bend for Vertical Bar of Column.
Always remember that vertical column bars are known as longitudinal bars and the longitudinal bars should be bent at 90 degree & length should not be less than 18’’ or 1.5 feet.
88). Hook’s Angle of Stirrup.
Hook angle of stirrup’s is 135°.
89). Length of Hook should not be less than 9 D (Diameter of Bar) for one side.
90). End Hook’s Angle of Longitudinal Bar.
End Hook angle for Longitudinal Bar of Beam & Column should be with 90 degree.
91). End hook is provided at both end of longitudinal bar.
92). The length of hook should not be less than 12 db. Where db is the diameter of bar.
93). Hook’s Length of Stirrup.
The formula for calculating stirrups hook length is “ 6 d ’’ where d is the diameter of bar. But stirrups hook length should not be less than 3”.
94). End hook of Slab Top Reinforcement.
End hook length of slabs top bar should not be less than 12 db Where db is the diameter of bar.
95). Anchorage length of Cantilever Member.
The anchorage length of main bar of a cantilever R.C.C member should not be less than 69 db.Where db is the diameter of bar.
i). 3 d or 300 mm ( Whichever is less ) for main steel.
ii). 5 d or 500 mm 9 Whichever is less ) for distribution of steel.
97). Beam Sections.
i). Balanced sections
X U = X U Max.
Pt = pt ( lim ).
ii). Under Reinforced
= X 4 < X U Max.
Pt < pt ( lim ).
iii). Over Reinforced
= X 4 > X U Max.
Pt > pt ( lim ).
98). Effective width of flange for T beam & L beam.
i). For T – Beam
bf = L 0 / 6 + b w + 6 D F
ii). For L – Beam
bf = L 0 / 12 + b w + 3 D f
99). Stress – Strain diagram points for singly Reinforced section.
i). Maximum Strain in Concrete in compression = 0.0035
ii). Maximum Stain in Steel in Tension = 0.87 f y / ES + 0.002
iii). Maximum Stress in Concrete = 0.45 f c k
iv). Maximum Stress in Steel = 0.87 f y
100). Development Length for R.C.C Members.
L d = 0.87 f y x diameter of bar
4 x Bond Shear Stress
101 ). For Deformed bars bond shear stress increased by 25% .
102).For bars in compression it is increased by 60% .
103). R.C.C Column.
i). Short Column = Le/D < 12
ii). Long Column = Le/D > 12
i). One Way Slab = L y / L x > 2
Spanning in one direction only.
ii). Two Way Slab = L y / L x < 2
Spanning in both direction.
105). Deflection Control Value for slabs & beam.
Basic value of span / depth ratio for deflection control are as below
S.S Slab = 20
Cantilever = 07
Continuous Slab = 26
So, Guys These are the 100 TECHNICAL TERMS ABOUT REINFORCEMENT.
Thanks for your Great Attention to read this post.I hope this articles might be useful for all of you.
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