DOI : 10.17577/IJERTV9IS030583
- Open Access
- Authors : Harsh Rana , Dr. Darshana R. Bhatt , Dr. Snehal V. Mevada
- Paper ID : IJERTV9IS030583
- Volume & Issue : Volume 09, Issue 03 (March 2020)
- Published (First Online): 06-04-2020
- ISSN (Online) : 2278-0181
- Publisher Name : IJERT
- License:
This work is licensed under a Creative Commons Attribution 4.0 International License
High Rise Long Span Steel Structure with Semi-Rigid Connection using Bracing System
Harsh Rana1, Dr. Darshana R. Bhatt2, Dr. Snehal V. Mevada3 Post Graduate Student1, Associate Professor2, Assistant Professor3 Department of Structural Engineering
Birla Vishvakarma Mahavidyalaya (BVM) Engineering College, Gujarat, India.
Abstract: Generally, in steel structure the connection between beam and column are designed as moment connection and pinned connection, but in actual condition the structure behaves between these two conditions, resulted into semi-rigid condition which is intermediate stage between rigid and pinned joints. Effect of semi-rigid connection on multi-story multi-bay frame is accomplished in this paper. The present study introduces the effect of static and dynamic loading on high rise steel structure of G+15 story with 4m, 6m and 8m three bay span length. Structure is analyzed under two different condition of partial release of semi-rigid connections which is derived by fixity factor of values 0.5 and 0.75 (as per AISC) in this study. The analysis is done commercially available software-STAAD.Pro. From the non-linear analysis, the story displacement and story drift are obtained. The overall performance of the structure from the analysis, semi-rigid joints display more story displacement and story drift compared to rigid joints. To overcome the results, bracing system is introduced at different location of periphery of structure. These brace frame structure consist of X- bracing and diagonal bracing. Again, comparative analysis is to be performed in STAAD.Pro on these three-bay span lengths. It is found that braced semi-rigid frame structure perform quite well as compared to unbraced frame structure.
Keywords: Multi-story Multi-bay frame, Semi-rigid connections, Fixity factor, Brace frame.
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INTRODUCTION
Steel structures are made up of different elements like beams, columns, bracings, flooring and roofing systems. In every structure Beam-to-column connections are important and inherent component of steel frame structure and their behavior influence the global performance of the structure under various loadings. Generally, connections are characterized in two types 1. Moment Connections and 2. Pinned connections. Besides that in actual practice steel connections are not providing ideal rigid or pinned but behavior of connections fall between these two-condition called as semi-rigid connections which basically based on their stiffness criteria. Basically, Connections are classified by their strength as well as their ductility, where ductility is a description of the rotation capacity i.e. rotational stiffness. As per AISC (American institute of Steel construction) fixity factor is derived to evaluate rotational stiffness of member of the structure which is conventional practice but it gives approximate value of partial releases in the structure as well as their behaviour is also influenced on the rotational stiffness of the member
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LITERATURE REVIEW
Nandeesha and Kashinath (2017) Investigated the analysis of multi storey steel space frame by varying fixity factor and found the capacity of strength of joints and to perform linear static of semi-rigid connection steel frame using response spectrum method. Considering 0 fixity f actor for pinned or hinged joints and 1 for rigid joints and the variation of bending moment, shear Force with varying fixity factor was found out. Nihan dogramac aksoylar, Hussam mahmoud (2011) have studied the moment resisting frame with semi- rigid connections and prepared 26 sample model frames were evaluated with pushover and dynamic analysis under
25 strong ground motion records. Main outcome of investigation was overall top story displacement of structure with semi-rigid structure are smaller than rigid frame structure. Peng deng, yigjuan, Xiaotong shang (2015) had studied comparison of eccentric inclined braced steel frame with semi-rigid connection and simple steel frame with semi-rigid connections. Based on seismic performance the energy dissipation capacity was found out in terms of lateral stability and stiffness of the structure. Mohammad razavi, Ali abolmmali (2014), came up with new concept of hybrid steel frame system, as it contains the mixture of full rigid and semi-rigid steel connections used in 20-storey steel structure. They assigned the semi-rigid connections as replacement of rigid connections at different location of structure. By performing the parametric study of seismic analysis, they corelate the cyclic behaviour of HYBRID frame structure in terms of storey drift and life safety. Anuraj e, Hemalatha g (2018), their effort was made to find out actual behaviour of rigid and semi rigid connection by performing nonlinear static analysis on G+5 storey structure in SAP2000. From analysis, storey drift value and performance points were obtained
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METHOLOGY FOR ANALYSIS
There are many methods to find out capacity of semi-rigid connections, but in this paper needs to estimate rotational stiffness of member of structure. Main aim to analyse the performance of high rise (G+15 storey) long span steel structure with semi-rigid connections using bracing system. It is proposed to carry out the analysis of multi-story multi- bay frame (contains 4m,6m & 8m bay length) considering the ideal rigid and semi-rigid conditions using STAAD.Pro and evaluate the effect of height, span, fixity factor,
rotational stiffness. Apart from this analysis, in this research widely investigated the comparative analysis of semi-rigid connection with
Study of various Parameters in Semi- Rigid connections
or without bracing system. As per convenience, X- Bracing and Diagonal bracing are used at different location of periphery of structure.
The primary aim of this study to compare the two types of partial release condition as per fixity factor equation.
Fixity factor considered 0for ideally pinned conditions and 1 fixity for rigid conditions in the analysis of frame. As per past experiences and researches the most favourable results
are obtained for the range of 0.5 to 0.7 fixity factor.
Present study incorporates the analysis of steel frame structure using fixity factors 0.5 and 0.75 (i.e. 50% partial release structure and 25% partial release in structure). In end fixity factor, ri is written as
With bracing
Analysis and design of long span high rise steel framed structure with semi rigid connection
Without bracing
Under static, seismic non-linear loading
Under static, seismic non-linear loading
Ri: Rotational Spring Stiffness of connections
EI/L: Flexural Stiffness of elements
Using above equation, there are 63 models prepared as per different conditions of fixity factor (0.5 and 0.75), bay lengths and bracing system. The flow chart of methodology of analysis and classification of models are mentioned below.
Connections
Rigid Semi-rigid
Flow chart 1: Scope of study
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ANALYSIS
All primary data are mentioned in table-1 & 2. Apart from this, section properties and loading conditions are given in table- 3 & 4.
Structural Data
Building type
Symmetrical High-rise G+15 storey
Numbers of bay
3 In both direction
Bay length
4m, 6m and 8m
Height of building
48m
Building type
/td>
Symmetrical High-rise G+15 storey
Numbers of bay
3 In both direction
Bay length
4m, 6m and 8m
Height of building
48m
Table 1: Primary structural data
As per Different bay length 4m, 6m & 8m and also Different bracing system Total No.
Middle
Without bracings
Corner
With bracings
Fixity Factor
Rotational Stiffness (kN.m/rad)
ISWB 250
ISWB300
ISMB300
ISMB400
0.5
9360.4
12375.22
13550.67
25777.6
0.75
26754.9
39188.18
42910.465
81629.02
Fixity Factor
Rotational Stiffness (kN.m/rad)
ISWB 250
ISWB300
ISMB300
ISMB400
0.5
9360.4
12375.22
13550.67
25777.6
0.75
26754.9
39188.18
42910.465
81629.02
Table 2; Rotational stiffness of members
of Models- 63
z
Full perimeter
Section
Area (m2)
Modulus of elasticity (E) (kN/m2)
Moment of inertia (I) m4
ISWB 250 X
40.9
0.005205
210000000
0.000059431
ISWB 300 X
48.1
0.006133
210000000
0.000098216
ISMB 300 X
44.2
0.005626
210000000
0.000086036
ISMB 400 X
61.6
0.007846
210000000
0.000204584
Section
Area (m2)
Modulus of elasticity (E) (kN/m2)
Moment of inertia (I) m4
ISWB 250 X
40.9
0.005205
210000000
0.000059431
ISWB 300 X
48.1
0.006133
210000000
0.000098216
ISMB 300 X
44.2
0.005626
210000000
0.000086036
ISMB 400 X
61.6
0.007846
210000000
0.000204584
Table 3 : Section properties of beams
Dead load + Live load
4 kN/m2
Beam section (UDL) (For all structures)
ISWB250 ISWB300 ISMB300 ISMB400
0.409 kN/m
0.481 kN/m
0.442 kN/m 0.615 kN/m
Column Section
IW500400X012 IW500400X2040 I160016A50040
Bracings
(For all structures)
ISA 150X150X16
Dead load + Live load
4 kN/m2
Beam section (UDL) (For all structures)
ISWB250 ISWB300 ISMB300 ISMB400
0.409 kN/m
0.481 kN/m
0.442 kN/m 0.615 kN/m
Column Section
IW500400X012 IW500400X2040 I160016A50040
Bracings
(For all structures)
ISA 150X150X16
Table 4 : Loadings and primary data of columns and bracing
In STAAD.Pro, the partial releases are providing at start and end of the beam members which is mentioned below fig-1.
Figure 1: Using Partial Release in Beam Section for semi rigidity
Mainly two type of bracing system (X and diagonal) are provided on different location of periphery of structure. The detailed rendering view of structures are presented in fig-2 & 3.
Figure 2: Different locations of provision of X – Bracings
Figure 3: Different locations of provision of diagonal Bracings
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PARAMETERS FOR EARTHQUAKE AND
WIND ANALYSIS
Table 4: Seismic analysis data
AS PER IS 1893 2016 PART I
USING RESPONSE SPECRTRUM ANALYSIS
City
Ahmedabad
Zone
III 0.16
Response Reduction Factor(R)
5 (Steel Structure with SMRF frame)
Importance Factor(I)
1
Combination Method
CQC method
Soil Type
Medium Soil
Damping Ratio
0.05
(Sa/g)*(Z/R)
0.016 (X and Z direction)
Time
5.94 s
Acceleration
3.33426 m/s2
Table 5: Wind analysis data
AS PER IS 875 PART- III 2015
Design Wind speed
Vz = Vb*K1*K2*K3 Where Vb = 39 m/s
Height (m)
Wind pressure(kN/m2) pz = 0.6*Vz2
10
0.732
15
0.796
20
0.859
30
0.930
48
1.133
After providing bracing (X and diagonal), reduction in lateral displacement as per bay lengths are shown in fig-6 to fig-11.
-
RESULTS
From the parametric analysis results (in mm) are in terms of lateral displacement and lateral drift (Both permissible
<=L/300) as characterized in three different (4m, 6m & 8m) bay length nd fixity factors are mentioned below.
-
For 50% release i.e fixity factor is 0.5
-
For 25% release i.e fixity factor is 0.75
Also, measure the effect of bracing system (X and Diagonal Bracing) on lateral stability of structure.
200
150
200
150
The results comparison of lateral displacement between rigid connection and semi-rigid connection for three bay lengths are shown in fig- 4 and 5.
250
250
238
238
Displacement for Bay length 4m
Displacement for Bay length 4m
80
70
60
50
40
30
20
10
0
71
61
80
70
60
50
40
30
20
10
0
71
61
0.5 0.75
Full perimeter Middle Corner
0.5 0.75
Full perimeter Middle Corner
28
28
31
31
22
22
21
21
Figure 6: X-bracing
170
170
400
350
300
250
200
150
100
50
0
100
100
97
97
50
0
50
0
Displacement
4m 6m 8m
Displacement
4m 6m 8m
Figure 4: Rigid Connections
Displacement
335
288
335
288
308
220
160
122
4m 6m 8m
140
120
100
80
60
40
20
0
Displacement for bay length 4m
117
100
72
75
63
65
0.5 0.75
Full perimeter Corner Middle
Figure 7: Diagonal bracing
0.5 0.75
Figure 5: Semi-Rigid Connections
Displacement for bay length 6m
Displacement for bay length 6m
Displacement for bay length 6m
Displacement for bay length 6m
32
32
120
100
120
100
99
99
80
80
91
91
60
60
59
59
40
40
56
56
20
20
31
31
0
0
0.5
0.5
0.75
0.75
Full perimeter Corner Middle
Full perimeter Corner Middle
91
91
160
140
120
100
80
60
40
20
0
160
140
120
100
80
60
40
20
0
137
137
118
118
97
97
103
103
94
94
0.5 0.75
Full perimeter Corner Middle
0.5 0.75
Full perimeter Corner Middle
Figure 8: X-bracing
Displacement for bay lengh 8m
Displacement for bay lengh 8m
140
120
100
80
117
110
140
120
100
80
117
110
60
40
20
0
68
64
60
40
20
0
68
64
0.5 0.75
Full perimeter Corner Middle
0.5 0.75
Full perimeter Corner Middle
44
44
43.9
43.9
Figure 10: X-bracing
Figure 9: Diagonal bracing
Displacement for bay length 8m
Displacement for bay length 8m
180
160
140
120
100
80
60
40
20
0
162
180
160
140
120
100
80
60
40
20
0
162
0.5 0.75
Full perimeter Corner Middle
0.5 0.75
Full perimeter Corner Middle
135
135
150
150
110
110
98
98
93
93
Figure 11: Diagonal bracing
25
20
15
10
25
20
15
10
80
70
60
80
70
60
75
75
50
40
30
20
50
40
30
20
55
55
Same as the comparison of results of lateral drift between rigid connection and semi-rigid connection for three bay lengths are shown in fig-12 and 13.
Drift
Drift
Drift
Drift
35
30
33.3
35
30
33.3
0
4m
6m
8m
0
4m
6m
8m
4m 6m 8m
0.5 0.75
4m 6m 8m
0.5 0.75
10.8
10.8
5
5
6.4
6.4
28
28
10
0
10
0
21
21
16
16
11
11
Figure 12: Rigid Connections Figure 13: Semi-Rigid Connections
As per different bay lengths and bracing system comparison of lateral drift are as shown in fig- 14 to 19.
Drift for bay length 4m
Drift for bay length 4m
Drift for bay length 4m
9
8
7
6
5
4
3
2
1
0
9
8
7
6
5
4
3
2
1
0
6
7.63
7.63
5.12
4.93
3.97
2.9
1.58
1.27
5.12
4.93
3.97
2.9
1.58
1.27
5
5.32
5.32
4
6
5.98
6
5.98
4.86
4.86
3
3.96
3.96
2
1
0
0.5 0.75
Full perimeter Corner Middle
0.5 0.75
Full perimeter Corner Middle
0.5 0.75
Full perimeter Corner Middle
Figure 14: X-bracing Figure 15: Diagonal bracing
Drift for bay length 6m Drift for bay length 6m
9
8
7
6
5
4
3
2
1 1.9
0
4.15
3.8
10
9
8
7
6.31
6.31
6 7.15
5
4
3
2
1
0
4.67
4.67
5.98
1.36
1.36
7.63
7.63
6.5
6.5
8.58
8.58
7.32
7.32
0.5 0.75 0.5 0.75
Full perimeter Corner Middle Full perimeter Corner Middle
Figure 16: X-bracing Figure 17: Diagonal bracing
Drift for bay length 8m
Drift for bay length 8m
Drift for bay length 8m
14
12
10
8
6
4
2
0
14
12
10
8
6
4
2
0
9
7.9
6.88
5.91
4.83
2.56
2.03
7.9
6.88
5.91
4.83
2.56
2.03
8
12.19
12.19
7
6
9.15
9.15
8.25
8.25
5
7.19
7.19
7.02
7.02
4
5.55
5.55
3
2
1
0
0.5 0.75
Full perimeter Corner Middle
0.5 0.75
Full perimeter Corner Middle
0.5 0.75
Full perimeter Corner Middle
Figure 18: X-bracing Figure 19: Diagonal bracing
-
-
CONCLUSION
-
From the overall analysis, it has been observed that lateral displacement in semi-rigid connection is more than rigid connections as well as increasing in bay length.
-
Reduction in results with increasing the flexibility of connection about fixity factor 0.75 as compare to fixity factor 0.5.
-
As span increase the more lateral displacement observed. To overcome this effect the bracing system is used to improve the lateral stability of structure. The analysis results of X-braced frame have indicated more lateral stability than diagonal braced frame.
-
In the overall seismic analysis of high-rise structure, corner and full perimeter braced frame enhance to give least lateral displacement and drift comparing with middle braced frame from above figures.
-
-
REFERENCES
-
Nandee-sha G. , Kashinath B. Rugi, Nov-2017, Influence of semi-rigid connection on behavior of steel frame under static loads, International Research journal of engineering and technology (IRJET), vol. 4, pp. 1441-1445.
-
Arunraj e and hemalatha G, Nctober 2018, Performance analysis of semi rigid connection over rigid and hinged connections, International journal of civil engineering and technology (IJCIET) vol-9, pp.1749-1755.
-
Mohammad Razavi, Ali Abolmaali, 22 February 2014, Earthquake resistance frames with combination of rigid and semi-rigid connections, Journal of Constructional Steel Research, vol-98, pp. 1-11.
-
Nihan Dogramac Aksoylar , Amr S. Elnashai , Hussam Mahmoud , 9 July 2010, The design and seismic performance of low-rise long-span frames with semi-rigid connections, Journal of Constructional Steel Research, vol-67, pp. 114- 126.
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Peng Deng, Yingjuan Ma ,Xiaotong Shang, Research on Seismic Behavior of Semi-rigid Steel Frame Structures With Eccentric Brace, 5th International Conference on Advanced Engineering Materials and Technology (AEMT 2015).
-
Sanjaykumar N. Sonune, Dr. Nagesh L. Shelke, 2017, Response of structural steel frame by using semi-rigid connections, International journal of advance research and innovative ideas in education, vol-3, pp. 1675-1686.