LATERAL PERFORMANCE OF HIGH RISE BUILDING INCORPORATING SPACE SHEAR WALL AGAINST WIND
LIM WEI JIA
FACULTY OF ENGINEERING TECHNOLOGY
UNIVERSITI MALAYSIA PERLIS
LATERAL PERFORMANCE OF HIGH RISE BUILDING INCORPORATING SPACE SHEAR WALL AGAINST WIND
LIM WEI JIA
Report submitted in partial fulfillment
of the requirements for the degree
of Bachelor of Engineering Technology
1.1 Background of Study
The development of tall buildings has been prolonged in major cities of Malaysia such as Kuala Lumpur, Penang and Johor Bahru due to the rapid growth of urban population (Fadzil, 2016). The structural stability of tall building is not only depended on the ability to withstand axial load, but also the lateral performance. Besides, the city such as Penang, due to the geographical location which is an island, it is frequently exposed to wind along the years (Deraman & Chik, 2014). Thus, the impact of wind acting on tall building becomes an important aspect and challenge in structural design.
Nowadays, shear wall is the most common structural element to maintain lateral performance of high rise building in Malaysia. They are flexural members and which normally constructed in high rise buildings to avoid the total collapse of the high rise buildings under lateral loading. The high in-plane stiffness and strength of shear wall are used to resist large horizontal loads and support gravity loads simultaneously. However, the shear wall still have the limitation on building space and opening of window and door (Abd-El-Rahim & Farghaly, 2010).
Therefore, a new innovative structure element known as space shear wall, which is a space frame system, to resist the lateral forces generated by the wind activities. The space shear wall will able to maintain the lateral performance while giving advantage such as providing ability of allowing natural lighting (Bayat, Ghazali, & Tahir, 2014).
In this research, a study has been carried out to determine the lateral performance by applying space shear wall in high rise building model. The models with and without space shear wall will be tested by numerical analysis and physical testing to verify.
1.2 Problem Statement
The rapid growth of urban population and increased income in the Southeast Asia has prolonged the development of tall buildings which are either used for residential or commercial purposes (Fadzil, 2016). In Penang, there is a higher proportion of new high-rise buildings are going to develop in coming years (Lim, 2015). Besides that, Penang is also a city that exposed to wind frequently along the years. The average wind speed of building in Penang is about 29.79 m/s (Deraman & Chik, 2014). The impact of wind acting on tall building becomes an important aspect in structural design.
Shear wall is the most common structural element to maintain lateral performance of high rise building in Malaysia. However, the application of shear walls limited the demandable of architectural openings (windows & doors) in the exterior views of such buildings (Abd-El-Rahim & Farghaly, 2010). The shear wall occupied more space in a building and obstructed natural lighting. Besides, with the trend of development of high rise in Malaysia, the main challenge for structural engineers nowadays is to optimise the performance and construction cost for creating an excellent lateral system (Bayat et al., 2014). The innovation of advanced systems such as mass tuned damper can help to dissipate lateral load but these systems require high production cost to implement. Therefore, this research introduces space shear wall, which is a space frame system, which allow more natural lighting and space, while also strengthen the lateral resisting performance without costing too much has been introduced.
The objectives of this study are:
i. To analyse lateral displacement of high rise building with and without space shear wall against wind.
ii. To compare various configuration of space shear wall to be applied.
iii. To verify the outcome between software analysis (SAP 2000) and wind tunnel test.
1.4 Scope of Study
In this research, the behaviour of a structure is studied based on the lateral performance when exposed to wind loading. The study of wind loading is based on Penang location only. It focussed on the stiffness of structure and distribution of loading to increase the stability of a structure. The application of space shear wall is studied for its properties to resist lateral loading.
The structures of this study are 16 storeys height of building. The structure with shear wall is the control specimen. Another several structures with different configuration of space shear wall are going to study. The parameters of these studies is the lateral displacement of the structure. For wind tunnel testing, models will be tested by measuring its displacement against wind load applied.
1.5 Significant of Study
The implementation of space shear wall can be determined by analysing the lateral displacement when wind load applied. The outcome can be verified with results from wind tunnel test. The application of space shear wall is significant in future construction field. Space shear wall is not only has stiffness and high damping to dissipate lateral energy, it also provide the odds to compatible with architectural consideration and encouragement of natural lighting (Bayat et al., 2014). Besides, it is not only applicable in new development of high rise building, but also able to retrofit existing building when more lateral resisting capacity needed.
1.6 Thesis Outline
The thesis is divided into 5 chapters which are introduction, literature review, methodology, result and discussion while the last chapter is conclusion and recommendation. Chapter 1 (Introduction) discussed the research background, problem statement, objective of research, scope of study, significant of study and also the outline of the thesis.
Chapter 2 (Literature Review) discussed regarding the demand of high rise building, concept of lateral resisting system and concept of shear wall against wind from previous published works. Some information such as wind speed, equivalent static wind load, lateral loading are stated in this chapter. Besides that, the principal and application of the space shear wall also being discussed in this part of chapter based on previous study.
Chapter 3 (Methodology) described the details of method used for this research. This chapter explain the calculation of wind loading and equivalent static wind load sequences of modelling, assignment of material and loading, and analysis by using SAP2000. Besides, this chapter includes the procedure of constructing the structure and the configuration of space shear wall in the structure. The wind tunnel testing procedure is also discussed in this part.
Chapter 4 (Results and Discussion) is the part to analyse result and discuss for this research after performing the simulation and testing. This means that how the space shear wall affect lateral performance of structure against wind is analysed and discussed. Besides that, the configuration of space shear wall affecting lateral performance is being determined. In addition, the comparison between the software simulation and wind tunnel testing.
Chapter 5 (Conclusion) indicated the conclusion of this research and achievement of the objectives. The application of space shear wall had been discussion after the conclusion. There are also included the recommendation for the future works or researches. This thesis concludes with a References List and Appendix.
This chapter is discussing on the previous of related studied done by other researcher. In this chapter, an overview of demand of high rise building and wind behavior in Malaysia are discussed. The existing lateral system such as shear wall and proposed new system, space shear wall are also discussed. The lateral performance of high rise building is also presented when exerting lateral loading.
2.2 High Rise Building
A ‘tall building’ is defined as a multi-story structure in which most occupants reach their destinations on higher floor depend on elevators (lifts) (Craighead, 2009). This tall building can be categorized as low, mid, high and super high rise (skyscraper). The low rise building is defined as less than four stories, mid rise is considering from five up to fifteen stories, while high rise is ranging from sixteen to fifty and more than fifty stories is the skyscraper (Fadzil, 2016).
Besides, The National Fire Protection Association (NFPA) defined a high-rise building as a building taller than 75 ft (23 meters) in height measured from the lowest level of fire department vehicle access to the floor of the highest occupiable storey (Mohamad Yatim, 2009). Another opinion says a high-rise structure is one that extends higher than the maximum reach of available fire-fighting equipment and it is between 75 ft and 100 ft (23 meters to 31 meters) (Craighead, 2009).
The overall slenderness of a high rise building is defined by its “height-to-base ratio”, being the height of the building divided by its narrowest plan dimension. Basically, higher height-to-base ratios and lower natural frequencies increase the dynamic component of the response to wind. A building with a height-to-base ratio of more than around 5 is expected to respond to wind loads in a significantly dynamic way (where building inertial effects are significant) (Kayvani, 2014).
In fact, New York’s most advanced towers are defined not by their height but by their width or rather, their slenderness. The slenderness ratio is defined as the ratio between a building’s height and its smallest width. For example, a 1,000ft (310m) height of tower that has 100ft (31m) at its narrowest width would have a slenderness ratio of 10:1. “The slenderness of a building is maybe more important than anything else,” said by Silvian Marcus, director of building structures at WSP USA (Runaghan, 2014). In New York’s building code, designs for buildings over 600ft (183m) and any building with a slenderness ratio above 7:1 must be peer reviewed by another engineering practice (Runaghan, 2014).
Therefore, the issue of slenderness must also be considered. A measure of a building’s slenderness is the aspect ratio. For core wall only lateral systems, ratios typically range from 10:1 to 13:1. For lateral systems that engage exterior elements, an aspect ratio up to 8:1 is feasible. Pushing this ratio up to 10:1 can result in the need for special damping devices to mitigate excessive motion perception (Zils & Viise, 2013). The space shear wall system is considered as exterior lateral element, due to the consideration of authenticity in real construction, the ratio used in this research is 4:1.
2.2.1 Demand of High Rise Building
Nowadays, due to the increasing of population in urban areas in Malaysia such as Penang, Kuala Lumpur, Selangor and Johor Bahru, demand for housing is increasing and development of high-rise residential schemes is accelerated in these high-density areas due to scarcity of land for development of landed residential properties (Tiun, 2009). These high rise properties are being promoted because high rise living became a logical response to soaring of land prices. There are successful example countries that implement high rise such as Singapore and Hong Kong where the traditional lifestyle is high-density, high-rise living (Tiun, 2009).
In Penang, there is a trend of developers preferring to build tall building such as condominiums. In coming years, especially on Penang Island, there is a higher proportion of new high-rise units (Lim, 2015). According to Table 2.1, on the statistics obtained from the National Property Information Centre (NAPIC), it is estimated that there were at least 203,618 units of high rise properties inclusive of flats, condominiums and apartments are under constructing for incoming supply in Malaysia by the end of 2017 and the number is growing yearly. From the data, Penang is the third highest state in constructing more high rise building which is about 35,793 units. This is due to the high demand of housing in this developing area.
Table 2.1: Incoming Supply of High Rise Building in Malaysia as of Q3 2017
State Low Cost Flat Flat Condominium/ Apartment Total
Selangor 2887 6255 43859 53001
W.P. Kuala Lumpur 0 0 40460 40460
Pulau Pinang 7280 8256 20257 35793
Johor 2451 4451 13011 19913
Sabah 3562 418 12426 16406
Sarawak 0 0 8801 8801
Table 2.1 – continued
Perak 0 724 6264 6988
W.P. Putrajaya 0 0 6944 6944
Pahang 0 840 3488 4328
Negeri Sembilan 0 1684 1588 3272
Kelantan 218 1001 1451 2670
Melaka 250 324 1392 1966
Terengganu 640 35 612 1287
W.P. Labuan 0 0 1143 1143
Kedah 416 0 196 612
Perlis 0 0 34 34
Malaysia 17704 23988 161926 203618
Source: Residential Property Stock Table Q3 2017, NAPIC.
2.3 Size of Column and Beam
Based on a study on wind behavior of buildings with and without shear wall (in different location) for structural stability and economy (Gourav P. Bajaj, 2016), the column size is 600 mm x 600 mm and beam size is 500 mm x 300 mm. The building dimension is 20 m in length and 15 m in width with a height of 47.6 m. The research is about determination of shear wall application toward wind load which is similar to this study, the dimension of building is also almost similar in this study. Therefore, the size of column and beam is determined as 600 mm x 600 mm and 500 mm x 300 mm respectively.
2.4 Shear Wall
Shear wall is a structural element installed in a building to resist horizontal forces parallel to the plane of the wall. Due to its highly in plane stiffness and strength, it can resist large both horizontal loads and support gravity loads simultaneously (Sardar & Karadi, 2013). The main horizontal forces that are induces by the shear wall are wind, earthquake and other lateral forces. They are mainly flexural members and mostly provided in high rise buildings to avoid the total collapse of the high rise buildings under seismic forces, wind forces or other lateral forces (Gourav P. Bajaj, 2016). Figure 2.1 and Figure 2.2 show the construction of shear wall in high rise building.
Sources: Kopczynski, 2011
Figure 2.1: Construction of shear wall of 40-storeys residential tower at Eighth and Pine.
Sources: PERI Group, 2017
Figure 2.2: Construction of shear wall of 26-storeys Aspen Residence in George Town, Malaysia
When the buildings are tall, which are more than twelve storeys or so, the sizes of beam and column need to be constructed larger and reinforcement at the beam and column junction works become heavier, therefore, there is a lot of obstruction at to place and vibrate concrete at these joints, which generally will affect the safety of buildings (Gourav P. Bajaj, 2016). So, the present of shear walls in high rise buildings solves these practical difficulties. However, recent RC tall buildings would have more complicated structural behavior than before. Shear wall system with irregular openings are that undergoes both lateral and gravity loads, and may result some especial issues in the behavior of structural elements and stability of structure (Abd-El-Rahim & Farghaly, 2010). Besides, installation of openings in the shear walls can affect on the top displacements of the buildings and it is related with openings arrangement system of openings. The top displacement is agreed quit well with that induced in shear walls without openings but this obstructs the transmission natural lighting into the building (Abd-El-Rahim & Farghaly, 2010). Therefore, new system called space shear wall which is a combination of shear wall and space frame structure is introduced to modified traditional shear wall.
2.5 Space Frame Structure
Space structure is defined as a three-dimensional structural system assemble in single, double or multiple layer with interlocked strut elements & joint-connections (Bayat et al., 2014). Besides, innovation of space structures provided the domineering features emphasizing the giant impact exerted by three-dimensional structures upon modern architecture and structural engineering (Makowski, 2018). Space frame connection is the most determinant component in order to connecting linear members and distributing the imposed loads in three-dimensional manner (Bayat et al., 2014).
The space frame can be formed either in a flat or a curved surface. The earliest form of space frame structures is a single layer grid. By adding intermediate grids and including rigid connecting to the joist and girder framing system, the single layer grid is formed. The major characteristic of grid construction is the omni-directional spreading of the load as opposed to the linear transfer of the load in an ordinary framing system. Since such load transfer is mainly by bending, for larger spans, the bending stiffness is increased most efficiently by going to a double layer system. The load transfer mechanism of curved surface space frames essentially different from the grid system that is primarily membrane-like action (Wai-fah, 1999).
A good example of space structure is Baltimore-Washington International Thurgood Marshall Airport (BWI Airport) shown in Figure 2.1. Baltimore-Washington International Airport is an international airport located in Linthicum, an unincorporated community in northern Anne Arundel County, Maryland, United States. The airport has the signature space frame design while increasing passenger capacity and improving the traveler’s experience. The design is a 90-foot atrium, topped by a large skylight, floods the upper and lower levels, including waiting and shopping areas, with natural light, while supported by the steel space frame elements. This project even won the WBC (Washington Building Congress) Craftsmanship Award for the Metals/Structural Steel Categories (Airport Technology, 2018).
Sources: Airport Technology, 2018
Figure 2.3: Space frame structure of Baltimore-Washington International Thurgood Marshall Airport
The advantage of a space frame structure is lightweight properties. The material is distributed spatially in such away that the loads transfer mechanism are primarily axial loads which are in tension or compression (Makowski, 2018). Furthermore, space frames can be built from simple prefabricated units, which are often of standard size and shape. Such units can be easily transported and rapidly assembled on site by semi-skilled labor. Besides, space structure compatible with architecture aspect. Architects appreciate the visual beauty and the impressive simplicity of lines in space frames. A trend is very noticeable in which the structural members are left exposed as a part of the architectural expression. Desire for openness for both visual impact as well as the ability to accommodate variable space requirements always calls for space frames as the most favorable solution (Wai-fah, 1999).
2.6 Space Shear Wall
Space Shear Wall is space trusses to resist the lateral forces generated by the wind activities. Such lateral forces may be resisted quite effectively by integration of three-dimensional structures with two dimensional lateral systems like cross bracing, where the building frame is designed to carry the vertical loads, and the bracing the lateral force (Bayat et al., 2014). The concept of space shear wall can be simplified as the combination of shear wall and space structure. Figure 2.2 shows the initial concept of space shear wall.
Sources: Bayat et al., 2014
Figure 2.4: Initial Concept of Space Shear wall
The idea of Space shear wall is based on the capability of space trusses to resist the lateral forces generated by the seismic activities or wind activities. These lateral forces may be resisted by integration of three-dimensional structures with two dimensional lateral systems quite effectively where the building frame is designed to carry the vertical loads, and the space truss resists the lateral force (Sutjiadi ; Charleson, 2014).
The expected advantages of space shear wall are high stiffness, ductility and energy dissipation, lightness, industrialization, maintainability and reparability, compatibility with architectural considerations, low cost, simple and fast fabrication. These advantages are expected based on the structural performance of space truss under past earthquakes and its unique characteristics (Bayat et al., 2014).
Space structure is high stiffness due to its three-dimensional geometric and proper contribution of loading by its interconnected elements (G.S. Ramaswamy, M. Eekhout, G.R. Suresh, 2002). Table 2.2 shows a list of famous space structures with their free span length and carried dead load. The large free span and imposed heavy load in existing space structures demonstrate the high stiffness of space structures.
Table 2.2: Examples of Famous Buildings Using Space Frame Structures
Project Free Span (m) Dead Load (kPa)
Currigan Hall 55 –
Sao Paulo Exhibition Center 60 –
Boeing 747 Hanger, London Airport, 1970 84 11.1
Omni Coliseum 107 7.3
Expo 68, Osaka 108 15.2
Pauly Pavilion 122 7.8
Kloten Airport, Zurich, 1975 128 18.8
Nartia Airport, Tokyo, 1972 190 25.6
Source: Bayat et al., 2014
Besides that, space shear wall is compatible with architectural consideration. Architects always wish to design long vertical structure with fewer structural components (Sutjiadi ; Charleson, 2014). Therefore, there is development of space structures in previous years. Space frame structure is a precious system that can optimise between engineer and architect to create a new forms, that provide wider application, flexibility and diversity. High intention by one of the most famous architects, Lord Norman Foster, is frequently applying the exposed spatial structural elements in his architectural design, as shown in Figure 2.6 (Bayat et al., 2014). By using space shear wall, the integration between structural and architectural elements can be improved and investigated on its challenges in high-rise buildings as demonstrated in Figure 2.5 (Sutjiadi ; Charleson, 2014). Therefore, space shear wall would be introduced as a compatible lateral resisting system for architectural considerations.
Sources: Sutjiadi ; Charleson, 2014
Figure 2.5: A Section of Three-Storeys Building Using Boundary Double-layer Space Structure
Source: Bayat et al., 2014
Figure 2.6: Architectural-Structural Integration of Space Grid Structures a) 30 St Mary Axe, London b) Hearst Tower, New York c) Almaty Twin Tower, Almaty d) Double-Layer Space Structure of an un-built 150 storeys Project, Chicago e) Gakuen Spiral Tower, Nogoya f) Skytree Tower, Tokyo International
2.7 Lateral Load
Lateral loads are defined as the live loads in the form of horizontal force acting on the structure. Typical lateral loads would be a wind load against a facade, an earthquake, the earth pressure against a beach front, retaining wall or the earth pressure against the basement wall (Hoogendoorn, 2009). Most lateral loads vary in intensity depending on the buildings geographic location, structural materials, height and shape. The dynamic effects of wind and earthquake loads are usually analyzed as an equivalent static load in most small and moderate sized buildings (Brownjohn, 2015).
2.7.1 Wind Behaviour
Wind is a phenomenon of great complexity because of the many flow situations arising from the interaction of wind with structures. Wind has some negative and positive effects. For structural engineers, it always causes trouble with height (Lotfabadi, 2014). The average wind speed over a time period of the order of ten minutes or more, tends to increase with height (Mendis et al., 2007). Therefore, high rise building which is tall or slender, respond dynamically to the effects of wind. In Penang, an estimation of maximum wind speed at a building with height of 145.6m was conducted and indicated the value of 29.85 m/s (Deraman ; Chik, 2014). According to Malaysia Standard (MS1553:2002), the basic wind speed of Penang which categorised as Zone II is about 32.5m/s.
2.7.2 Wind Load
The principal lateral load this thesis is focused on the wind action. An introduction is presented to wind loading and wind-induced building response. It is tried to combine both wind engineering and the building code prescriptions (Hoogendoorn, 2009). The recommendations of Eurocode 1 are discussed and on occasion compared with the consulted literature on wind engineering (Hoogendoorn, 2009). Practically all building codes consider the wind action as a quasi-static load. To allow a static structural calculation, factors are introduced accounting for the spatial and temporal averaging of wind gustiness and the dynamic amplification of the building response (Patruno, Ricci, de Miranda, ; Ubertini, 2017). Eurocode 1 defines the wind load acting on any structure or element by:
F_w (z)=C_s C_d?C_f?q_p (z)?A_ref (2.1)
where F_w wind force N
C_s C_d structural factor –
C_f force coefficient –
q_p peak wind pressure Pa
A_ref reference area m2
2.7.3 Surface Wind Characteristics
Wind is defined as the motion of air with respect to the earth’s surface. The motion is caused by pressure differences in air layers of the same altitude (Patruno et al., 2017). These different air pressures are caused by variable solar heating of the atmosphere. Since buildings are located at the surface of the earth we are especially interested in the surface wind characteristics. The surface wind characteristics include variation with height and terrain roughness, turbulence and pressure (Hoogendoorn, 2009).
Variation with height and terrain roughness means that the surface wind varies strongly with height. It is approximately zero at the surface, and it increases with height in a boundary layer depth; ranging approximately from 100 m for low wind velocities over smooth surfaces to 4 km for extreme winds over rough surfaces. This layer is called the atmospheric boundary layer, and is schematically sketched in Figure 2.7. Above this boundary layer the wind flows approximately with a constant gradient wind velocity along the pressure isobars.
Sources: Hoogendoorn, 2009
Figure 2.7: Boundary Layer of Wind
The wind flow is highly turbulent in three dimensions when near to the earth’s surface. Turbulent velocity fluctuations in the air flow passing a point can be considered to be caused by a superposition of rotating “eddies”, transported by the wind with the mean velocity. These rotating eddies are three-dimensional turbulent vortices of varying size (Kay??o?lu, 2011).
Pressure is the force exerted on the surface per unit area. Depending on the wind direction and the porosity distribution of the building envelope, they can act in the same or opposite direction. The reference pressure in wind engineering is taken as the ambient pressure being the atmospheric pressure for true scale buildings. A pressure above atmospheric is called positive and below atmospheric is denominated negative or suction. There is a stagnation point on the windward side of buildings where the wind is completely blocked (Eurocode 1, 2010).
2.7.4 Structural Factor
The quasi-static approach of wind loading in the Eurocode requires the use of an additional factor to account for the dynamic effects in a static calculation. The Eurocode denominates the total dynamic effect as the structural factor. The structural factor is defined as the product of the size factor and the dynamic factor. The size factor c_s takes the improbability into account of the simultaneous presence of wind gusts over the building surface. The dynamic factor c_d takes into account the amplification of the structural response due to the resonance of the building structure with the longitudinal turbulence (Eurocode 1, 2010).
2.7.5 Equivalent Static Wind Load
Equivalent static wind loads (ESWLs) is the loading described as pivotal information for estimating the response under the combined action of wind and other loads, through a simple static analysis procedure, to ensure structural safety and serviceability (Chen ; Kareem, 2004). The basic idea underlying their definition is to search for a set of static load conditions which, once enveloped, provide the correct design value in each structural member (Patruno et al., 2017).
Several approaches to the determination of ESWLs have been presented. The gust loading factor approach, in its simplest version, assumes that the structural response to the time averaged wind profile can be appropriately amplified in order to synthetically take into account the structure dynamic response. Such an approach, although still widely used in practice due to its simplicity, is prone to numerous limitations, the principal one being the impossibility to describe effects which are null when the time averaged response is considered (Patruno et al., 2017).
The equivalent static wind load of this study is calculated by referring Uniform Building Code 1997. The uniform building code is dedicated to the development of better building construction and greater safety to the public by uniformity in building laws. The code is founded on broad-based performance principles that make possible the use of new materials and new construction systems. (UBC, 1997)
Every building should be designed and constructed to resist the wind effects by determining the requirements in uniform building code 1997. Wind should be assumed acting from any horizontal direction. The wind pressure cannot be reducted due to any shielding effect of adjacent structures. The structures which are sensitive to dynamic effects, such as buildings with a height-to-width ratio greater than five, and buildings over 400 feet in height, should be designed in accordance with approved national standard (UBC, 1997). Therefore, UBC 1997 acts as a guideline, which can ensure the safety and stability of the every structures by following standard design procedure in UBC 1997.
The total pressure from wind load can be calculated by applying the formula listed in UBC 1994 section 2316. This formula is listed below :
P = Ce Cq qs I (2.2)
Where P = design wind pressure
Ce = combined height, exposure and gust factor coefficient as given in Table 126.96.36.199 in Appendix A
Cq= pressure coefficient for the structure or portion of structure under consideration as given in Table 188.8.131.52 in Appendix B.
qs = wind stagnation pressure at the standard height of 33 feet (10000 mm) as set forth in Table 184.108.40.206 in Appendix C.
l = importance factor as set forth in Table 220.127.116.11 in Appendix D.
2.8 Lateral Performance of High Rise Building
Lateral performance of high rise building is the performance under lateral loads of a tall buildings. It is a significant characteristic especially when design tall building for the serviceability limit state (Melo Ferreira, 2014). In this research, the lateral performance is measured in term of lateral displacement. Due to lateral loads, there will be a drift or sway on the high rise structures and it is the magnitude of displacement at the top of a building relative to its base (Rahman, Farzana, ; Alam, 2014).
2.8.1 Lateral Displacement
As far as the ultimate limit state is concerned, building displacements due to horizontal loads must be limited to prevent collapse due to P-delta effects. P-Delta effect is secondary order loading effect which will happen in structure directly related to stiffness of building, The P-delta effect reduces the stiffness of structural elements (Yousuf Dinar, Samiul Karim, Ayan Barua, ; Ashraf Uddin, 2013). In the serviceability limit state, the lateral displacements are to be limited to prevent damage to or malfunctioning of non-structural components such as cladding on the building façade, partitions and interior finishes (doors, elevators, etc.). These problems in non-structural elements are caused by inter-storey drift. No universally adopted criterion exists with regard to the lateral displacement limit in the serviceability limit state (Hoogendoorn, 2009).
Nevertheless, values of the inter-storey drift of up to H/400 are normally considered as acceptable. In order to avoid an exhaustive calculation of all storey displacements, usually a global drift criterion is adopted with a limit of H/500, where H refers to the building height. Note that the overall drift criterion can be more or less conservative depending on the displacement diagram, i.e. whether the displacement diagram is shear or bending-dominated (Hoogendoorn, 2009).
2.9 Wind Tunnel Test
Wind Tunnel Test is a powerful tool that allows engineers to determine the nature and intensity of wind forces acting on complex structures. Wind tunnel testing is particularly useful when the complexity of the structure and the surrounding terrain, resulting in complex wind flows, does not allow the determination of wind forces using simplified code provisions (Mendis et al., 2007). The first attempts for building up such kind of a laboratory was resulted from the need of understanding the lift and drag forces acting on surfaces cutting through the atmosphere for the purpose of designing and making a flying machine (Kay??o?lu, 2011).
Wind tunnel experiments for tall buildings can be divided into three type which are synchronous multi-pressure scanning system (SM-PSS), high frequency base balance (H-FBB) and aeroelastic model tests. The SM-PSS tests types of the wind tunnel tests that are based on the pressure fluctuations on the models. The main purpose in this type is to measure the time series of instantaneous pressure distributions occurring on the exterior surfaces of the model utilizing pressure tubes mounted on it. Since the pressure fluctuation monitoring is the basis of the SM-PSS tests, they are mostly preferred for the pressure based design works such as the cladding design and the design of large-area roof systems. SM-PSS tests are very useful in the development and improvement works of the building design specifications since the codes approach to wind loading problems from the pressure point of view (Kay??o?lu, 2011).
The second type is the high frequency base balance (H-FBB) which is a type of a data acquisition and processing system that consists of ultra-sensitive force measurement arrangements. The balance system constitutes of ultra sensitive load cells for the purpose of measuring the five base response components that are basically the moments about the three orthogonal axes (x,y,z) and the two base shears as time series. Besides, the third type is aeroelastic test. When a lightly damped, low mass and highly flexible structure experiences wind-induced oscillations, the deformations in turn lead to amplifications in the wind loads that the structure feels. This phenomenon is known as wind / structure interaction and it may result in aeroelastic instability with a possible unfavourable consequence such as inadmissible deformations/accelerations or it may also result in lesser extreme effects than predicted (Kay??o?lu, 2011).
In this research, the wind tunnel that is going to use is the UTM low speed wind tunnel. The UTM low speed wind tunnel is commissioned in 2001 and has served for more than 7 years. The clients include researchers from universities and designers from industries such as USM, UTeM, UPM, MINDEF, MODENAS, PROTON and others. UTM wind tunnel has capability to provide widerange of testing include aircraft, ground surface vehicle and industrial aerodynamics such as building, bridges, street-lantern light and wind turbine (Mansor, 2009). Figure 2.8 shows the wind tunnel in UTM, Skudai, Johor.
Figure 2.8: Wind Tunnel in UTM, Skudai, Johor.
This chapter discussed about the design of the structural, dimension of the structure, parameter of study, assignment of wind speed, and the method of the testing on the structural in order to obtain the lateral performance under wind loading. Initially, the problem statement is determined in order to develop the ideas of the title. After that, three objectives are decided based on the problem statement to scope down the research field. Literature Review is then been carry out to study more on the paper that have been done from the previous researcher which are related. The papers that have been reviewed are regarding the high rise building, wind load, space shear wall, lateral performance of building against wind, analysis and the method that used to obtain the result in the testing on the structural. In these chapter, the way to obtain the parameter will be discussed. The steps of design, assign and analyse in SAP2000 are shown. 16 storey building with and without space shear wall is design and analysed by using SAP2000. In addition, down scale models will be constructed and tested in wind tunnel. The flow chart is showed on the Figure 3.1.
3.2 Flow Chart of Overall Research
The flow chart for overall research activities is shown in the Figure 3.1.
Figure 3.1: Flow Chart of Methodology
The parameters required in this study are height of building, base dimension of building, wind speed at Penang. All the informations are referred journal or thesis from previous related research and standard. According to the manual of standard building specification (European Commission, 2011), the typical height for a normal building for general purpose is 3.0m. Therefore, the floor to floor height of this study is decided to be 3.0m as well. As stated in 2.2 (High Rise Building), the high rise building is defined as a building which having between sixteen to fifty stories. To meet the high rise building requirement, the building in this study is 16 stories, which by multiply by 3.0m for each floor, the total building height is 48m.
As discussed in 2.2 (High Rise Building), the slenderness of this building (height-to-base ratios) is decided as 4:1. This indicated that the narrowest width of building is 12m. Therefore, the base dimension of building are 20 m in length and 12 m in width. The layout plan of this building is shown in Figure 3.2. Whereas, Figure 3.3 shows the direction of wind exert on the building.
Figure 3.2: Layout plan of building
Figure3.3: Structure of buiding and wind direction
3.4 Determination of Wind Speed
To determine the wind load to be assigned in structure design analysis, the data of maximum wind speed, average wind speed, maximum wind gust and average wind gust are obtained from Weather Underground. The data obtained is from the year 2013 to 2017 and set location in Penang.
From Figure 3.4, the data showed the highest maximum wind speed from 2013 to 2017 is 42 km/h (11.67 m/s) and the highest average wind speed from 2013 to 2017 is 11 km/h (3.06 m/s). While, the lowest maximum wind speed and average wind speed from 2013 to 2017 are 5 km/h (1.39 m/s) and 23 km/h (6.39 m/s) respectively. Besides that, the highest maximum wind gust from 2013 to 2017 is 69 km/h (19.17 m/s) and the highest average wind gust from 2013 to 2017 is 52 km/h (14.4 m/s). Whereas, the lowest maximum wind speed and average wind speed from 2013 to 2017 are 27 km/h (7.5m/s) and 32 km/h (8.89 m/s) respectively. This shows that there are no much different between the highest and lowest wind speed, the wind in Penang can be consider as static wind.
Furthermore, based on 2.6.1, an estimation of maximum wind speed at a building with height of 145.6 m was conducted and indicated the value 29.85 m/s in Penang (Deraman ; Chik, 2014). According to Malaysia Standard (MS1553:2002), Penang is fell on the Zone II in Malaysia, which means that the basic wind speed of Penang is about 32.5 m/s. So, the wind speed that decided to be used in this study is 32.5m/s.
Source: (Weather Underground, 2018)
Figure 3.4: Maximum and Average Wind Speed and Wind Gust from 2013 to 2017 in Penang (km/h).
3.5 Equivalent Static Wind Load
Base on Uniform Building Code 1997, equivalent static wind load can be computed by using equation 2.2 which the details of the equation was discussed in Chapter 2. Ce is the coefficient of combined height, exposed and gust factor which can be obtained by referring Table 18.104.22.168 in Appendix A. Penang is a town which might surrounded by others building, so it is considered as exposure B. By interpolating of level height, the Ce value can be obtained for each level. The structure is primary frames and system, so the values of Cq are 0.8 for windward wall and 0.5 for leeward wall by referring Table 22.214.171.124 in Appendix B. As mention in 3.4, the wind speed decided to be used is 32.5 m/s (72.7 mph), the qs value can be obtained by referring Table 126.96.36.199 in Appendix C, which the qs is 16.4 psf. By referring Table 188.8.131.52 in Appendix D, the important factor lw is 1 since the structure is standard occupancy structure. Table 3.1 below summarise the parameter to be used.
Table 3.1: Parameter to be used in design
Basic Wind Speed 32.5 m/s (72.7 mph)
Height of Building 48 m (157.48 ft)
Important Factor, Iw 1.00
Exposure Category Category B
In this study, the wind load exerted on each floor of the structure are calculate by using UBC 1994 and the wind pressure distribution along the height of building is shown in Table 3.3. The windward pressure and leeward pressure of the structure acting on 1st storey 8.1344 psf and 5.0840 psf while the highest windward pressure and leeward pressure acting on 16 storey of the structure are 17.0963 psf and 10.6852 psf. The total windward pressure and leeward pressure are214.4020 psf and 134.0012 psf respectively. Table 3.2 shows one example of calculation step while Table 3.3 and Figure 3.5 shows wind pressure distribution along the height of building.
Table 3.2: Example calculation of wind pressure distribution on each storey
Reference Design Calculation Remarks
For the 1st storey,
Level Height = 3m (9.84ft)
Ce = 0.6200
Primary frames and systems
Cq (windward) = 0.8
Cq (leeward) = 0.5
Basic wind speed = 32.5 m/s (72.7 mph)
qs = 16.4 psf
Standard occupancy structure
Iw = 1.00
P = CeCqqslw
P = (0.62)(0.8)(16.4)(1.00)
P = 8.1344 psf
P = CeCqqslw
P = (0.62)(0.5)(16.4)(1.00)
P = 5.0840 psf
Windward pressure at 1st storey
= 8.1344 psf
Leeward pressure at 1st storey
= 5.0840 psf
Table 3.3: Wind pressure distribution along the height of building
Storey Level Height Ce Cq Pressure, P (psf)
(meter) (feet) Windward Leeward Windward Leeward
1 3 9.84 0.6200 0.8 0.5 8.1344 5.0840
2 6 19.69 0.6669 0.8 0.5 8.7491 5.4682
3 9 29.53 0.7562 0.8 0.5 9.9216 6.2010
4 12 39.37 0.8350 0.8 0.5 10.9547 6.8467
5 15 49.21 0.8907 0.8 0.5 11.6856 7.3035
6 18 59.06 0.9448 0.8 0.5 12.3958 7.7474
7 21 68.90 0.9900 0.8 0.5 12.9893 8.1183
8 24 78.74 1.0343 0.8 0.5 13.5704 8.4815
9 27 88.58 1.0786 0.8 0.5 14.1515 8.8447
10 30 98.43 1.1229 0.8 0.5 14.7326 9.2079
11 33 108.27 1.1589 0.8 0.5 15.2053 9.5033
12 36 118.11 1.1934 0.8 0.5 15.6572 9.7858
13 39 127.95 1.2219 0.8 0.5 16.0309 10.0193
14 42 137.80 1.2489 0.8 0.5 16.3861 10.2413
15 45 147.64 1.2760 0.8 0.5 16.7412 10.4632
16 48 157.48 1.3031 0.8 0.5 17.0963 10.6852
Total pressure: 214.4020 134.0012
Figure 3.5: Wind pressure distribution along the height of building.
3.6 Configuration of Space Shear Wall
2 types of configuration of space shear wall will be installed in the structure. The space shear wall will be installed at the wall side which parallel to the axis that will be exert the wind loading for all 16 stories. For model 1, which will be the structure installed with typical shear wall as the control specimen. For model 2, the space shear wall will be installed fully at the for 4 bay of structure while model 3 will only be installed at the center 2 bay of structure only. Figure 3.6 and Figure 3.7 shows the model of configuration of space shear wall.
Figure 3.6: 3D model of configuration of space shear wall.
Figure 3.7: Side view of configuration of space shear wall.
3.7 Analysis of Structure
By collecting all data and parameter needed, the analysis of structure can be done by using SAP 2000. As mention in 2.3 (Size of Column and Beam), the size of column is 600 mm x 600 mm while the size of beam is 500 mm x 300 mm. The material will be Concrete Grade M25 with main and secondary steel reinforcement of Grade 500. The equivalent static wind load is obtained as calculated in 3.5 and to be assigned in SAP 2000 analysis. The principal steps to analyse using SAP 2000 are define material, define beam and column sections, design geometry of model, assign support, define load patterns, assign loading, define load combination. After that, the analysis can be run and results obtained can be interpreted by graphically review or table of data.
Firstly, as launch the software SAP 2000, a new file is opened by selecting new model in File tab. 3D frame is selected and the unit is set as kN, mm, C as shown in Figure 3.8 below. By inserting 16 stories, 3000 mm storey height, 4000 mm bay width for X direction, 3000 mm for Y direction, 5 bays in X direction and 4 bays in Y direction as shown on Figure 3.9.
Figure 3.8: Selection 3D frame and unit of kN, mm, C.
Figure 3.9: Dimension of 3D frame
After that, adding new material property of Concrete M25, with strength of 25 N/mm2 and its properties. Adding another new material for reinforment steel bar, with strength 500 N/mm2 and its properties. Materials defined shows in Figure 3.10. By then, frame sections are defined which are Column 600 mm x 600 mm and Beam 500 mm x 300 mm shown in Figure 3.11. The material for both is conrete M25 with rebar Grade 500.
Figure 3.10: Define of Material Properties
Figure 3.11: Define of section properties
In this research, since the objective is to study the lateral performance of structure when acting on wind, only static wind load will be defined and assigned to the structure. The wind load is based on the calculation in 3.5, which is computed based on the wind speed in Penang and condition. The auto lateral load pattern is selected for UBC 97 and the wind speed and exposure are modified as shown in Figure 3.12 and Figure 3.13.
Figure 3.12: Define of load patterns
Figure 3.13: Modification of auto lateral load pattern
After that, define load cases and load combinations as shown in Figure 3.14 and Figure 3.15. Add code-generated user load combinations by selecting the concrete frame design as shown Figure 3.16.
Figure 3.14: Define of load cases
Figure 3.15: Define of load combinations
Figure 3.16: Adding of code-generated user load combinations
Lastly, the analysis can be run by selecting Run Analysis in Analyse tab as showns in Figure 3.17, the result will be discussed in Chapter 4.
Figure 3.17: Analysis of design
3.8 Wind Tunnel Testing
After simulation analysis by using SAP 2000, a down scale model will be constructed and carried out wind tunnel test in UTM wind tunnel. UTM wind tunnel is a closed circuit type which the air is continuously recirculated leading to a less noisy and an efficient test. The test section is 2.0 m width x 1.5 m height x 5.8 m Length, built by solid wall. The maximum wind speed can be achieved 80 m/s. For this study, the wind speed will be set as 32.5 m/s. The testing result will be discussed and compare with result from simulation analysis in Chapter 4.