PERFORMANCE OF DIAGONALS IN HIGH RISE STEEL STRUCTURES · Performance of Diagonals in High Rise...

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International Journal of Civil Engineering and Technology (IJCIET) Volume 10, Issue 02, February 2019, pp. 1082-1092, Article ID: IJCIET_10_02_104

Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=10&IType=02

ISSN Print: 0976-6308 and ISSN Online: 0976-6316

© IAEME Publication Scopus Indexed

PERFORMANCE OF DIAGONALS IN HIGH

RISE STEEL STRUCTURES

Ali Hussein Ali

Assistant Teacher, Civil Department, Southern Technical University

Basrah, Iraq

ABSTRACT

In future one will continue to construct buildings interesting rather than

monotonous, however this has to be done at the cost of poor performance of buildings.

The braced system will give more flexibility in architectural design and it is structurally

more efficient compared to other normal framing systems and lateral load resisting

systems like shear wall, core wall systems, and tubular framing system and outrigger

structural systems.

In this study the behaviour of the high rise steel structure with and without braces

and different type of braces like X-type, A-type, V-type and single diagonal type brace

are studied by comparing results of different models. Dynamic Analysis by response

spectrum is carried out using ETABS 2016. The results are discussed through various

parameters like displacement, storey drift, storey stiffness etc.

Key words: Braced system, Dynamic Analysis, High rise

Cite this Article: Ali Hussein Ali, Performance of Diagonals in High Rise Steel

Structures, International Journal of Civil Engineering and Technology, 10(02), 2019,

pp. 1082–1092

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=02

1. INTRODUCTION

Tall structures are not as easy for construction as that of normal buildings due to the huge action

of lateral loads, displacements due to these Bending moments and shear force effects will be

more. Braced framed structures are usually considered to resist the lateral forces and to resist

the earthquake loads. Braced systems usually provide strength, stiffness to the structures.

They provide more stiffness against the horizontal shear because the diagonal member

elements work in axial stress. Braced frames develop their resistance to lateral forces by the

bracing action of diagonal members. Full braced frames are more rigid from economic point

of view arbitrarily braced ones have least forces induced in the structure.

In tall structures, the beams and columns are generally arranged in orthogonal pattern in

both elevation and plan. In a braced frame building, the resistance to horizontal forces is

Ali Hussein Ali


provided by two orthogonal bracing systems. In Bracing systems materials used for

construction are steel, concrete and wood. But steel is mainly used as a construction material

for high rise buildings which are more than 60 storeys.

Figure 1. Types of bracing systems

2. LITERATURE REVIEW

2.1. Dhanapalagouda Patil et al., (2015) [1]

In this paper they had explained about lateral resisting system called steel tube structure with

bracing system. And compared Frame structures with different bracing systems. For the

analysis purpose they had considered set of models consists of Frame structures, Tube

structures, Tube structures with mega bracings and Tube structure with Diagrid bracings.

Strength and stiffness based on design approach had been taken into account to resist lateral

loads wind load). For this study 45 storey is considered with floor height of 4m for all models.

They concluded that the,

� Steel tube structures systems were aesthetically stiffer than the frame structure in

terms of displacement.

� Steel tube structures with mega bracing system are most efficient in lateral

Displacement and Drift.

� The diagrid tube structure had lowest of all compared to other models.

� The steel tubular structure with mega bracing system exhibits least displacement.

2.2. Manish s. et al., (2014) [2]

In this paper comparative study of response of braced and un-braced building subjected to

lateral loads, suitable bracing systems, analyse the response of unsymmetrical building with

braces subjected to seismic loading by using software SAP2000.

The analysis purpose G+11 floors with each height of 4m are considered. The braced

building of the storey drift decreases as compared to the un-braced building. Storey drift,

Performance of Diagonals in High Rise Steel Structures


displacement, base shear, bending moment of building, axial force are considered and

compared with the models. After analysis the result and the conclusions are,

� The braced building of the storey drift decreases as compared to the unbraced

building.

� The displacement of the building decreases depending upon the different bracing

system employed and bracing sizes.

3. BACKGROUND

Steel is the material of choice for design because it is inherently ductile and flexible, it flexes

under extreme loads rather than crushing and crumbling. Structural steel’s low cost, strength,

durability, design flexibility, adaptability and recyclability continue to make it the material of

choice in building construction. The basic philosophy of rigid frame structure design is by

conducting "Fixed" or "Hinged" vertical member base conditions. A fixed column base is

always a strong frame and helps in controlling allowable deflection in the frame. Steel

designers commonly preferred fixed base compared to hinged base frames.

In fixed base design, the frame is rigid, but transfers heavy moments to the foundations In

like manner for hinged support, the frame does not transfer any moment to the foundation and

just vertical & horizontal responses influence the design of foundation. The most ideal way we

could discover is to "Brace" the frame to control the increasing deflection.

Figure 2. Building with bracings

4. MODEL DETAILS

The models considered in this study are 30 floors with Seismic Zone-V as per IS-1893 Details of the models are as follows:

� Total number of stories : G+29

� Height of typical floor : 3.0m

� Height of ground floor : 4.5m

� Number of bays in X-direction : 5

� Number of bays in Y-direction : 4

� Dimension: 25m x 20m

Ali Hussein Ali


� Depth of slab : 150mm

� Size of brace : ISA100X75X10mm

� Size of beam : ISMB 450 up to 15 floors

� ISMB 300 for remaining 15 floors

� Size of column : ISHB 450 up to 15 floors

� ISHB 350 for remaining 15 floors

Support Condition is fixed at base, grade used for concrete is M20 and grade for steel is

Fe250.

Live load:

i) For all floors = 3.0 kN/m2

ii) For roof = 2.0 kN/m2

Floor finish:

i) For all floors = 2.0 kN/m2

ii) For roof = 1.5 kN/m2

Along with above load, wall load is also considered.

Earth Quake Data:

Zone factor, Z

0.36 (For Zone 5)

Importance Factor, I 1.5

Soil type II(Medium)

Response

reduction factor 5 (SMRF)

Eccentric ratio 0.05

Modal combination Complete Quadratic Combination (CQC)

Directional combination SRSS



Model without bracing –MWB Model with backward bracing ONE bay –MBB1

Model with X bracing ONE bay –MXB1 Model with V-bracing ONE bay –MVB1

Model with A-bracing ONE bay –MAB1 Model with backward bracing 3 bay –MBB3

Ali Hussein Ali


Model with X bracing 3 bay –MXB3 Model with V-bracing 3 bay –MVB3

Model with A-bracing 3 bay –MAB3

5. RESULT DISCUSSIONS & CONCLUSIONS

Figure 3. Comparison of storey displacement values




The figure 3 shows comparison between bare frame model and model with X-bracing and

backward bracing for displacement parameter, it was observed that displacement is reduced by

20% in model with x-bracing and 16% in model with backward bracing in comparison to model

without bracing.

Similarly in figure 4 comparison is made between X-bracing and backward bracing for one

and three bays, the model with bracing in 3 bays shows decrease in displacement value by 18%

approximately in comparison with model with bracing in one bay.


The below table I shows comparison between brace provided in one bay for A-type and V-

type brace with model without brace. The variation is anywhere between 15 to 20%. Out of all

options X-bracing model shown better result in controlling displacement values.

Ali Hussein Ali


TABLE 1 Storey displacement comparison

Story RSX- Displacement, mm

MWB MAB1 MVB1

30 1108.768 887.348 905.8

29 1093.012 867.838 885.7

28 1072.897 845.391 862.8

27 1047.847 820.387 837.3

26 1017.935 792.871 809.3

25 983.392 762.916 778.9

24 944.493 730.647 746.2

23 901.512 696.227 711.4

22 854.718 659.853 674.6

21 804.372 621.755 636.0

20 750.746 582.203 595.9

19 694.151 541.514 554.6

18 635.021 500.065 512.5

17 574.266 458.304 470.0

16 514.761 417.063 428.0

15 467.687 381.465 391.6

14 437.546 354.975 364.6

13 408.084 328.718 338.0

12 378.375 302.573 311.5

11 348.323 276.511 285.1

10 317.958 250.523 258.7

9 287.334 224.621 232.5

8 256.519 198.847 206.3

7 225.588 173.266 180.3

6 194.628 147.974 154.5

5 163.734 123.101 129.1

4 133.01 98.815 104.2

3 102.561 75.322 79.9

2 72.429 52.826 56.4

1 42.155 30.989 33.4



Figure 6. Comparison of storey drift values

Figure 7. Comparison of storey drift values

The figures 6 explains drift parameter variation for model with X-bracing and backward

bracing provided in one & three bays. The model with X-bracing shows reduced drift value

compared other models. Figure 7 shows comparison between X-bracing, backward, and A-

bracing with model without bracing, bare frame shoed maximum values of drift by 20 to 25%.

Ali Hussein Ali


Figure 8. Comparison of storey stiffness values Figure 9. Comparison of storey stiffness values

The figures 8 & 9 shows relation between different models with respect to stiffness

parameter, model without bracing shows least value of stiffness whereas X-bracing and A-

bracing shows almost similar values.

Based on this work following conclusions are made.

� The model with X-bracing shown better performance in controlling lateral load in

comparison to all other type of brace.

� Structures located in seismic zone, need special configuration of structure with

respect to type of brace and location.

� A-type bracing shows second best type of bracing after X-type brace in reducing

lateral displacement and drift in tall steel structures.

� The bracings provided in more than one bay provides more rigidity to the structure.

� If bracings are provided in both direction of plan will results in to more stable

structure.

REFERENCES

[1] Dhanapalagouda Patil and Naveen M P (IJRET) 2015: Dynamic analysis of steel tube

structure with bracing systems.

[2] Manish S. Takey Volume 2, Issue 1 - seismic response of steel building with linear bracing

system (a software approach)

[3] P.Sairaj, K.Padmanabham volume 3, issue 2, February 2014 - Performance Based Seismic

Design of Braced Composite Multi Storied Building.

[4] Viswanath K.G, Prakash K.B, Anant Desai Volume 1, No 1, 2010 - Seismic Analysis of

Steel Braced Reinforced Concrete Frames

[5] Zasiah Tafheem, Shovona Khusru Volume 4, No 1, 2013- Structural behaviour of steel

building with concentric and eccentric bracing: A comparative study.



[6] Kulkarni J. G., Kore P. N., Tanawade S. B. Vol. 3, Issue 4, Jul-Aug 2013- Seismic

Response of Reinforced Concrete Braced Frames

[7] Adithya. M, Swathi rani K.S, Shruthi H K, Dr. Ramesh B.R volume 2 Issue 2 February

2015 - Study On Effective Bracing Systems for High Rise Steel Structures

[8] Manish S. Takey Volume 2, Issue 1 - seismic response of steel building with linear bracing

system (a software approach)

[9] A.Massumi and A.A.Tasnimi October 12-17, 2008,„Strengthening of Low Ductile

Reinforced Concrete Frames Using Steel X-Bracings with Different Details‟ the 14th

world conference on earthquake engineering Beijing, china.

[10] Chetan Jaiprakash Chitte (Jan-2014), „Effect Of Concentric Braces On The Behavior Of

Steel Structure By Pushover Analysis‟, IOSR Journal of Mechanical and Civil Engineering.

[11] A.Kadidd, D.Yahiaoui Procedia Engineering 14 (2011) 2899–2905 2011 -Seismic

assessment of braced RC frames.

[12] IS-875 (Part-1)-1987 code of practice for design loads (other than earthquake loads) for

buildings and structures: part-1 for dead loads

[13] IS: 875 (Part 2): 1987, “Code of practice for design loads (other than earthquake for

buildings and structures: Imposed loads”, Bureau of Indian Standards, New Delhi

[14] IS:1893 (Part 1): 2002, “Criteria for Earthquake Resistant Design of Structures”, Bureau of

Indian Standards, New Delhi

PERFORMANCE OF DIAGONALS IN HIGH RISE STEEL STRUCTURES · Performance of Diagonals in High Rise...

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