Wind Load Analysis and the Structure Optimization Design of the Steel Structures with ANSYS

Zhaoxin Meng a, Jianxin Zhao b , Shuyang Wangc and Nan Zhoud

College of Electromechanical Engineering, Northeast Forestry University, Harbin, 150030, P.R. China

amzhxmail@163.com, bzhaojianxin9112@126.com, cdljd28@yahoo.com.cn, dzhaonan851124@163.com

Keywords: Steel structure, Wind load, Bio-oil

Abstract. In recent years, the bio-oil, as a new kind of clean energy, has been paid with more

attentions and has been in rapid development. Meanwhile, the design and research of the bio-oil

equipment also has made a great progress. This paper presented the research of the main unit installed

steel structure which was with the 3000t yearly capacity. It analyzed and researched the structure and

load characteristics of the bio-oil main unit installed steel structure. According to the related research

theory and design standards, by using software ANSYS establish the three-dimensional model of the

main unit installed steel structure. The paper also analyzed and calculated the wind load. The model

structure has been optimized on the foundation of the analyzing preliminary model foundation. The

stability of the equipment has been enhanced.

Introduction

The biomass energy is one kind of new clean energy, and receives the attention and exploitation all

over the word [1]. The steel structure is the frame structural support of bio-oil main unit. The safe and

reliable of structure is one of the key factors for ensuring the normal operation of the main unit. The

design of the main unit steel structure frame involves the load function firstly [2]. Besides gravity of

itself, the installed steel structure also receives influence of the gravity action of the main unit

equipment installed in the frame the wind load on the frame and the earthquake load function. At present, we still dont have the unification calculation method of loads for the bio-oil main unit installed steel structure in our country. This paper analyzes the own load characteristic of the main

unit installed steel structure, and combines the research method of related fields and the designed

successful examples, summarizes the load function types of the main unit installed steel structure.

Use the ANSYS software to simulation analysis the wind load of the equipment.

Basic Points of the Main Unit Installed Steel Structure

Design Content. The main unit installed steel structure frame with the annual output bio-oil of 3000

tons. The equipment has been installed in Xi'an.

Basic Condition. The equipment for the design installation location is Xi'an, Shaanxi. The basic

wind pressure of Xi'an is 0.25kN/m2 [3]. The ground roughness is type B. The basis uses the pile

foundation [4].

Characteristics of the Main Unit Installed Steel Structure Frame. The number of plies of the

framework is 9. The total height is 27m. The arrangement of equipment is regular. The reactor frame

has 12 equipments on it in all. The heaviest operation weight of the equipment is lower than 10 tons.

The Wind Load Calculation

The main unit installed steel structure frame is the self-supporting high-rise structure. The wind load

is usually the main factors of causing the structure lateral displacement and vibration, and has the

control action [5]. Because this frame is the high-rise steel structure and has no particular heavy

equipment on it, the wind load calculation of this frame is the main control loads.

Applied Mechanics and Materials Vols. 37-38 (2010) pp 1643-1646Online available since 2010/Nov/11 at www.scientific.net (2010) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMM.37-38.1643

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Because the height of the equipment steel frame is large, the wind load on steel frame has a large

change along the height. The vast measured data of the along-wind wind load indicates that wind

effects can be decomposed into the mean wind and fluctuating wind two forms. The mean wind blows

the structure to the equilibrium position, and the fluctuating wind makes it vibrate around the

equilibrium position. This design steel height is 27m. The base is 6.3m6.6m. Load code for the design of building structures of China provides the wind load standard value of vertical function in

building surface unit area. The wind load standard value is calculated as follows:

0)()()( zzz zsz . (1)

Where, )(z is the wind load standard value of function in tower tube surface at the height of z

(kN/m2).Where, z is the wind vibration coefficient at the height of z. Where, )(zs is the wind load

shape coefficient, and it is equal to 0.62. Where, )(zz is the wind pressure height coefficient. Where,

0 is the basic wind pressure (kN/m2).

Due to needs of production, the production line needs to be located in the field as well as the

villages and towns and the urban suburb, belongs to the type B area. )(zz is calculated as follows

[6]:

32.0)1.0()( zzz . (2)

The main unit installed steel structure is the self-supporting high-rise structure. The wind vibration

coefficient is calculated as follows [5]:

)(/1 11 zzzBvz . (3)

Where, v is the correction coefficient of considering the section change, according to

characteristics of the main unit installed steel structure and the trait of the equipment arrangement,

v is equal to 1.5 from the literature four. Where, B is the correction coefficient of considering

section and quality changes, it is design for the ratio of windward side width and bottom width at the

height of the Z. B is equal to 0.6 in this design. Where, 1 is the fluctuating amplifying coefficient,

according to the literature four, it is approximate the value is 1.69. Where, 1 is the fluctuating

influence coefficient, when the ground roughness is type B, according to the literature four , 1 is equal

to 0.50. Where, z is the first vibration mode coefficient, the main unit installed steel structure frame

is belong to high-rise of bigger windward side. The frame plays a main effect. The vibration mode

coefficient can be obtained by appendix F of literature four. The wind pressure height coefficient, the

wind vibration coefficient and the standard value of the wind load are shown in Table 1.

Table 1 The standard value of the wind load in the highly area

Relative height Z/H the first vibration mode Coefficient z )(zz z )(z kN/m2

0.1 0.02 0.658 1.023 0.069

0.2 0.08 0.821 1.074 0.137

0.3 0.17 0.935 1.138 0.165

0.4 0.27 1.025 1.200 0.191

0.5 0.38 1.101 1.262 0.215

0.6 0.45 1.167 1.293 0.234

0.7 0.67 1.226 1.416 0.269

0.8 0.74 1.276 1.441 0.285

0.9 0.86 1.329 1.492 0.302

1.0 1.00 1.374 1.553 0.331

ANSYS Analysis and Optimization for Steel Structure

Finite Element Analysis for the Wind Load of Steel Structure. Using the ANSYS software

established the three-dimensional model of steel frame. According to 1:1 size of preliminary design

structure, the model is established and divided the finite element unit with the free mesh. The

1644 Advances in Engineering Design and Optimization

complete constraints are applied to the base of model. The wind load is loaded along the vertical

direction [7]. After finite element analysis the model is shown as the Fig.1.

(a) (b)

Fig. 1 The displacement distribute of model

Analysis results show that the maximum displacement of model is equal to 676.147mm in the

wind load conditions. The displacement is lager relative to the height of Model. Cant achieve standard of the equipment safe and stable operation. So the model structure needs a concrete analysis.

The structure needs more stable through strengthening and optimization, to achieve standard of the

equipment safe and stable operation.

The Steel Structure Optimization. According to the Design standard and the stable and

economical request of the steel structure design, the model has been improved gradually to be best.

To make the model achieved stable under economical premise. And find the final optimum design.

The optimized model is carried on the finite element analysis. Analyzed different optimization

models in the same constraint and wind load conditions. The analysis result of the optimal model is as

shown in Fig.2.

(a) (b)

Fig. 2 The displacement variant of the optimized model

Applied Mechanics and Materials Vols. 37-38 1645

Conclusion

According to the related standards and design examples, this paper analyzed the load characteristics

and the own structure of the main unit installed steel structure with the annual output bio-oil of 3000

tons. Based on the relevant research theory and design code it summarized the analysis and

calculation methods of the wind load of the main unit installed steel structure. Using finite element

analysis software ANSYS to establish the steel structure model, the variant size of model is analyzed

in the designed wind load conditions, and find the optimized model. The result achieved the stable

operation requirements of the main unit installed steel structure. The purpose of optimization design

is realized.

References

[1] J. Zhao and S.Y. Wang: Acta Energiae Solaris Sinica, Vol. 29 (2008) No. 1, pp. 90-94. (In

Chinese)

[2] P. Liu: Petrochemical Design, Vol. 26 (2009) No. 4, pp. 11-13. (In Chinese)

[3] GB 50135-2006: Code for Design of High Towering Structures (China Planning Press, China

2007). (In Chinese)

[4] GB 50007-2002: Code for Design of Building Foundation (China Academy of Building Research,

China 2003). (In Chinese)

[5] GB 50017-2003: Code for Design of Steel Structures (The PRC Ministry of Construction, China

2004). (In Chinese)

[6] GB 50009-2001: Load Code for the Design of Building Structures (China Architecture &

Building Press, China 2002). (In Chinese)

[7] H.S. Xu: ANSYS in Architectural Engineering Application (China Machine Press, China 2005).

(In Chinese)

1646 Advances in Engineering Design and Optimization

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