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The Hashtag Tower (Seoul , Korea)

REG 162- INTRODUCTION OF STRUCTURES

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REG 162- INTRODUCTION OF STRUCTURES

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REG 162- INTRODUCTION OF STRUCTURES

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REG 162- INTRODUCTION OF STRUCTURES

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REG 162- INTRODUCTION OF STRUCTURES

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REG 162- INTRODUCTION OF STRUCTURES

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REG 162- INTRODUCTION OF STRUCTURES

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REG 162- INTRODUCTION OF STRUCTURES

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REG 162- INTRODUCTION OF STRUCTURES

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REG 162- INTRODUCTION OF STRUCTURES

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LECTURE OUTCOME

• Audiences will comprehend the various stages of building construction

• Audiences will be able to distinguish the various classes of structures

• Audiences will be able to determine the structural determinancy of a truss structure

• Audiences will be able to perform the structural analysis of a determinate truss structure

REG 162- INTRODUCTION OF STRUCTURES

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WHO ARE WE?

• ARCHITECTS

• URBAN PLANNERS

• BUILDING ENGINEERS

• PROJECT MANAGERS

• BUILDING SURVEYORS

• QUANTITY SURVEYORS

• INTERIOR DESIGNERS

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WHAT DO WE DO?

• To ensure a structure is erected at the right location, aesthetically appealing and safe for occupancy with optimum cost of construction.

REG 163- Theory of Structures I

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WHAT IS OUR ROLE AS A BUILDING CONSULTANTS?

• Produce the architectural and engineering layout of a building.

• Estimation of loads (live, dead and dynamic loading)

• Analysis of forces, moments and deflection

• Design of structural members with adequate load bearing capacity

• Monitoring of compliance of site work to

design specification

REG 163- Theory of Structures I

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MAJOR STAGES IN BUILDING CONSTRUCTION

PROJECT FEASIBILITY STUDY

PROJECT PLANNING

ENGINEERING ANALYSIS AND DESIGN

PROJECT TENDER

PROGRESS AND COMPLIANCE MONITORING

AS-BUILT SURVEY AND INTEGRITY CHECK

ISSUANCE OF CERTIFICATE OF FITNESS

REG 163- Theory of Structures I

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ENGINEERING ANALYSIS AND DESIGN

SELECTION OF STRUCTURAL

FORM AND CLASS

• Determination of structural form and class according to site constraints, expected loading condition, load bearing requirements and cost consideration.

LOAD ESTIMATION

• Consideration on any type, nature and vector of potential load on the building.

STRUCTURAL ANALYSIS

• Determination of the vector of axial forces, shear forces, bending moments and deflection of a structure in response to the projected loads

STRUCTURAL DESIGN

• Specifying the dimensions of structural elements and its internal reinforcements (if any) to yield adequate load bearing capacity.

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CLASSIFICATION OF STRUCTURES

• Selection of structure element class is the utmost important consideration for effective transmission of a given load

• There are five basic categories of structural element based on the type of internal stress induced by the design load.

– Bending Structures

– Shear Structures

– Tension Structures

– Compression Structures

– Trusses

REG 163- Theory of Structures I

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CLASSIFICATION OF STRUCTURES

• Bending Structures – Bending structure is a horizontal structural member which is loaded

perpendicular to its longitudinal axis.

– Internal stress on the structure is combination of bending and shear stress.

– All external design load exerted on bending structures are transformed into bending and shear stress within the structure.

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CLASSIFICATION OF STRUCTURES

• Bending Structures – Suitable and economical for short spanned structures(<8 metres span)

– Quasi homogeneous materials with composite strength properties (Such as reinforced concrete) is suitable for fabrication of bending structures.

– Longer span (up to 20 metres) can be achieved using the pre-stress concrete technology.

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CLASSIFICATION OF STRUCTURES

• Shear Structures – Shear structure is a vertical structural member which is loaded

perpendicular to its longitudinal axis.

– Internal stress on the structure is mainly shear with negligible bending stress.

– All external design load exerted on bending structures are transformed into shear stress within the structure.

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CLASSIFICATION OF STRUCTURES

• Shear Structures – Shear structure is an essential element in tall building structures to

resist lateral load exerted by wind and seismic movement.

– In most tall building, shear walls are fabricated using reinforced concrete composite.

– Shear walls are also considered as a vertical support for beams and slabs in the design of reinforced concrete structures.

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CLASSIFICATION OF STRUCTURES

• Tension Structures – Internal stress on the structure is pure tension stress.

– All external design load exerted on tension structures are transformed into tension stress within the tension structure.

– Suitable and economical for long spanned structures(>15 metres span)

– Materials with good tensile strength properties (Such as steel and fibre reinforced polymers) is suitable for fabrication of tension structures.

– Tension structures is usually lacking in lateral stiffness and susceptible to wind-induced oscillation.

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CLASSIFICATION OF STRUCTURES

• Compression Structures – Internal stress on the structure is pure compression stress.

– All external design load exerted on compression structures are transformed into compression stress within the structural members.

– Economical for fabrication of long spanned structures.

– Materials with good compressive strength properties (Such as concrete and natural rocks) is suitable for fabrication of compression structures.

– Compression structures is usually lacking in lateral stiffness and susceptible to buckling failure.

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CLASSIFICATION OF STRUCTURES

• Trusses – Trusses are stable structural configuration which composed of

straight members connected at their ends

– Internal stress of an ideal truss system is either pure compression stress or pure tension.

– All external design load exerted on compression structures are transformed into either compression stress or tension stress within the structural members.

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CLASSIFICATION OF STRUCTURES

• Trusses – Economical for fabrication of long spanned structures.

– Homogeneous materials with good compressive strength and tension strength(Such as structural steel) is suitable for fabrication of truss structures.

– Can be subcategorized into two dimensional and three dimensional truss system.

– An efficient structural system which is both light weight and high strength.

– Not suitable for use when headroom is limited.

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PROJECT BRIEF

• TOTAL GROUP:25

• NUMBER OF STUDENTS PER GROUP:7-8

• NOTE: GROUP LIST CAN BE REFERRED IN THE ELEARN @ USM (elearning.usm.my) Portal

REG 163- Theory of Structures I

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PROJECT BRIEF

• PART 1: ASSESSMENT ON BENDING STRUCTURES 1.1 SUPPORT REACTION ASSESSMENT

1.2 SHEAR FORCE ASSESSMENT

1.3 BENDING MOMENT ASSESSMENT

• LABORATORY TECHNICIAN-IN-CHARGE:

PN DIANA ISME ISHAK

• GROUP COORDINATORS NEED TO BOOK THE LAB SCHEDULE WITH PN DIANA IMMEDIATELY AFTER TODAY CLASS.

• LAB ASSESSMENT WILL COMMENCE ON THE SECOND WEEK OF THE ACADEMIC SEMESTER

• THREE GROUP PER LAB SESSION

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PROJECT BRIEF

• PART 2: ASSESSMENT ON THE MECHANICAL PERFORMANCE OF STEEL REINFORCEMENT

2.1 PREPARATION OF STEEL REBAR AND PHYSICAL PROPERTIES ASSESSMENT

2.2 TENSILE AND YIELD STRENGTH PERFORMANCE

2.3 ASSESSMENT ON YOUNG’S MODULUS

• LABORATORY TECHNICIAN-IN-CHARGE:

PN. DIANA ISME ISHAK

• GROUP COORDINATORS NEED TO BOOK THE LAB SCHEDULE WITH THE TUTOR

• LAB WORK WILL COMMENCE ON THE SECOND WEEK OF THE ACADEMIC SEMESTER

• TWO GROUP PER LAB SESSION

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PROJECT REPORTING FORMAT

• TITLE PAGE (REFER TO STANDARD TEMPLATE IN E-LEARN)

• ACKNOWLEDGEMENT

• TABLE OF CONTENT

• CHAPTER 1:STRUCTURAL ASSESSMENT

• CHAPTER 2:PROPERTIES OF STEEL REINFORCEMENT

• CHAPTER 3:CONCLUSIONS

REG 163- Theory of Structures I

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REPORT SUBMISSION

• REPORT SHALL BE SUBMITTED INDIVIDUALLY

• SUBMISSION DATELINE:10TH MAY 2016

• CHANNEL OF SUBMISSION: E-LEARN SYSTEM

• DOCUMENT SHALL BE IN MS WORD FORMAT(doc. File)

• File name nomenclature order:

Group No._Student Name_Matric Number

• Severe action will be taken in the event of plagiarism

REG 163- Theory of Structures I

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ANALYSIS OF PLANE TRUSSES

• Four basic steps involved in the analysis of truss

Determination of truss structural condition

Identification of zero-force members

Determination of support reaction forces

Determination of internal forces of truss members

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ANALYSIS OF PLANE TRUSSES-STEP 1

• There are three basic truss structural conditions namely:

• Where m=number of members

r = number of reactions

j = number of joints

•Structurally unstable and not able to sustain any load.

•m+r<2j

Statically unstable truss

•Structurally stable and the forces in members can be determined with consideration on equilibrium of planar forces

•m+r=2j

Statically determinate

truss

•Structurally stable but the forces in members cannot be determined with consideration only on equilibrium of planar forces

•m+r>2j

Statically indeterminate

truss

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ANALYSIS OF PLANE TRUSSES

• m=17, j=10, r= 2

REG 163- Theory of Structures I

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ANALYSIS OF PLANE TRUSSES

• m=17, j=10, r= 3

REG 163- Theory of Structures I

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ANALYSIS OF PLANE TRUSSES

• m=21, j=10, r= 3

REG 163- Theory of Structures I

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ANALYSIS OF PLANE TRUSSES-STEP 2

• Identification of zero force members:

– Performed to expedite the analysis of forces of members in a truss system.

– There is only two conditions that a member of truss will have zero force.

REG 163- Theory of Structures I

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ANALYSIS OF PLANE TRUSSES-STEP 2

• Condition 1: If only two non-colinear member are connected to a joint that has no external loads or reactions applied to it. Then forces in both members are zero.

REG 163- Theory of Structures I

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ANALYSIS OF PLANE TRUSSES-STEP 2

• Condition 2: If three members, two of which are co-linear, are connected to a joint that has no external loads or reaction applied to it. The force in the member that is not co-linear is zero.

REG 163- Theory of Structures I

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ANALYSIS OF PLANE TRUSSES-STEP 3

• Determination of support reactions

• Conditions which can be employed are:

𝐹𝑦 = 0

𝐹𝑥 = 0

𝑀𝑃𝐼𝑁 𝑆𝑈𝑃𝑃𝑂𝑅𝑇 = 0

REG 163- Theory of Structures I

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ANALYSIS OF PLANE TRUSSES-STEP 4

• Determination of member forces

• Conditions which can be employed are:

𝑓𝑦 = 0

𝑓𝑥 = 0

REG 163- Theory of Structures I

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ANALYSIS OF PLANE TRUSSES-METHOD OF JOINTS

• Example 1:

What is the structural condition?

REG 163- Theory of Structures I

𝑚 = 5

𝑟 = 3

𝑗 = 4

𝑚 + 𝑟 = 8

2𝑗 = 8

𝑚 + 𝑟 = 2𝑗

Statically Determinate

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ANALYSIS OF PLANE TRUSSES-METHOD OF JOINTS

• Example 1:

Which one is zero force member?

Member BD

REG 163- Theory of Structures I

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EXAMPLE 1

Ax

Ay Cy

𝐹𝑥 = 0; 𝐴𝑥 − 28 = 0

𝐴𝑥 = 28𝑘𝑁

+

𝐹𝑦 = 0; 𝐴𝑦 + 𝐶𝑦 − 42 = 0

𝐴𝑦 + 𝐶𝑦 = 42𝑘𝑁

+

𝑀𝐴 = 0; 𝐶𝑦 35 − 42 20 + 28 20 = 0 +

𝐶𝑦 = 8𝑘𝑁

𝐴𝑦 + 8 = 42𝑘𝑁

𝐴𝑦 = 34𝑘𝑁

REG 163- Theory of Structures I

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ANALYSIS OF PLANE TRUSSES-METHOD OF JOINTS

• Consider Point A

Ax=28kN

Ay=34kN Cy=8kN

Ax=28kN

1

1

√2

Ay=34kN

FAD

FAB

𝑓𝑦 = 0; 34 + 𝐹𝐴𝐷1

2= 0

𝐹𝐴𝐷 = −48.08𝑘𝑁 (Compression)

+

𝑓𝑥 = 0; 28 + 𝐹𝐴𝐷1

2+ 𝐹𝐴𝐵 = 0

𝐹𝐴𝐵 = 6𝑘𝑁 (Tension)

+

28 + −48.081

2+ 𝐹𝐴𝐵 = 0

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ANALYSIS OF PLANE TRUSSES-METHOD OF JOINTS

• Consider Point B

Ax=28kN

Ay=34kN Cy=8kN

FAB=6kN FBC

𝑓𝑥 = 0;−6 + 𝐹𝐵𝐶 = 0

𝐹𝐵𝐶 = 6𝑘𝑁 (Tension)

+

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ANALYSIS OF PLANE TRUSSES-METHOD OF JOINTS

• Consider Point C

Ax=28kN

Ay=34kN Cy=8kN

FBC=6kN

4

3

5

Cy=8kN

FDC

𝑓𝑦 = 0; 8 + 𝐹𝐷𝐶4

5= 0

𝐹𝐷𝐶 = −10.00𝑘𝑁 (Compression)

+

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ANALYSIS OF PLANE TRUSSES-METHOD OF JOINTS

• Consider Point D (Checking Answer)

Ax=28kN

Ay=34kN Cy=8kN

28kN

1 1

√2

3 4

5

FAD=48.08kN

FDC=10.00kN

42kN

𝑓𝑦 = 48.081

2+ 10.00

4

5− 42 = −0.00231 ≈ 0

(OK)

+

𝑓𝑥 = 48.081

2− 28 − 10.00

3

5= −0 . 00231 ≈ 0

(OK)

+

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ANALYSIS OF PLANE TRUSSES-METHOD OF JOINTS

Ax=28kN

Ay=34kN Cy=8kN

0kN (ZERO FORCE MEMBER)

10kN (COMPRESSSION)

6kN (TENSION) 6kN (TENSION)

48.08kN (COMPRESSSION)

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TEST

• DATE:8 MARCH 2016

• DURATION: 1.5 HOURS

• SCOPE:

STRUCTURE CLASSES

TRUSS ANALYSIS

STRUCTURE FORM

REG 163- Theory of Structures I

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STRUCTURAL FORMS

• Structural form is a complex structural system whereby two or more structural classes are used in combination.

• The combination of a number of structural classes is often necessary to maximize the efficiency of load transfer and mitigation while meeting the architectural requirements namely: – Internal space and floor area

– Height of a structure

– Aspect ratios

– Spans between supports

– Geographical location of a project

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STRUCTURAL FORMS

• The five main structural form of building which can be found locally are as follows:

– Braced frame structure

– Rigid frame structure

– In-filled frame structure

– Shear walls structure

– Wall-frame structure

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BRACED FRAME STRUCTURE

• Load mitigation mechanism

– Dead and live gravity load is transferred by the conventional beam-column structural frames

– The gravity loads are transferred by the beams in the form of bending and shear stresses.

– Subsequently the load from the beams are transferred to the foundation by the structural columns in the form of compression stress.

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BRACED FRAME STRUCTURE

• Load mitigation mechanism

– Seismic and wind load are sustained by the diagonal bracing struts of the building structure

– Seismic and wind loading exerted on the building is converted into tension and compression stresses within the diagonal struts members

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BRACED FRAME STRUCTURE

• Advantages of the structural form

– High lateral stiffness and lateral load mitigation capacity

– Incurs minimum additional material and highly cost effective

– The sizes of the beams and slabs are independent of the height of building. This enable duplication of design for the beams and slabs for multiple floors.

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BRACED FRAME STRUCTURE

• Disadvantages of the structural form

– The presence of diagonal struts obstruct the planning of the windows location.

– High cost incurred for fabrication of diagonal strut joints.

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RIGID FRAME STRUCTURE

• Load mitigation mechanism

– Dead and live gravity load is transferred by the conventional beam-column structural frames

– The gravity loads are transferred by the beams in the form of bending and shear stresses.

– Subsequently the load from the beams are transferred to the foundation by the structural columns in the form of compression stress.

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RIGID FRAME STRUCTURE

• Load mitigation mechanism

– Seismic and wind load are mitigated by the rigid frame system which consist of columns and beams joined by moment resistant connection.

– Seismic and wind loading exerted on the building is converted into bending stresses at the moment resistant connection.

– The bending stresses are resisted by the additional internal reinforcements placed within the moment resistant connection.

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RIGID FRAME STRUCTURE

• Advantages

– The open rectangular arrangement of the structural form ease planning and placement of openings of a building.

– It is an ideal structural form for reinforced concrete building due to inherent rigidity of reinforced concrete joint.

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RIGID FRAME STRUCTURE

• Disadvantages

– Size of colums and beams are highly dependent on the height of the building. Hence, the design of floor members are not repeatable for the upper floors.

– Lateral load resistance capacity is limited, hence, not suitable for use in areas with active seismic activity.

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INFILLED FRAME STRUCTURE

• Load mitigation mechanism

– Gravity load transfer mechanism is similar to rigid frame and braced frame structure form.

– The space in between columns and beams are filled by concrete blocks instead of normal brick works

– Seismic and wind load are mitigated by the concrete blocks infills which act like a diagonal compression strut to brace the frame.

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INFILLED FRAME STRUCTURE

• Advantages

– Infills which normally serves as external or internal walls serves additional function of increasing lateral stiffness to resist lateral loads

• Disadvantages

– Unpredictable infill strength due to complex interaction behavior of infill and frame.

– Higher cost for placement of concrete blocks instead of conventional bricks.

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SHEAR WALL STRUCTURE

• Load mitigation mechanism

– Gravity load transfer mechanism is similar to rigid frame and braced frame structure form.

– Heavily reinforced concrete columns with high aspect ratios (>5) called shear walls are placed in the critical direction of the building

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SHEAR WALL STRUCTURE

• Load mitigation mechanism

– Shear walls can be designed in a form of planar walls or non planar assembly (in the form of lift cores)

– Seismic and wind load are transferred by the high stiffness shear wall system in the form of shear stresses which are eventually transferred to the foundation system.

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SHEAR WALL STRUCTURE

• Advantages

– Higher lateral stiffness and lateral load resistance as compared to infilled frame and rigid frame structures

– Exceptional seismic load resisting performance.

• Disadvantages

– The presence of large numbers of shear walls impose restriction on the planning of the internal spaces of a building.

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WALL-FRAME STRUCTURE

• Load mitigation mechanism

– The structural form consist of rigid reinforced concrete walls placed in the critical direction of a building.

– Dead and live gravity load is transferred by the reinforced concrete walls in the form of compressive stress to the foundation of the building.

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WALL-FRAME STRUCTURE

• Load mitigation mechanism

– Seismic and wind load are transferred by the high stiffness highly elongated reinforced concrete wall system in the form of shear stresses which are eventually transferred to the foundation system.

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WALL-FRAME STRUCTURE

• Advantages

– Very high lateral stiffness and lateral load resistance.

– The dimension of walls and floors are highly uniform. This allows the use of system form work which greatly expedite the construction progress.

• Disadvantages

– The presence of large numbers of elongated reinforced concrete walls impose heavy restriction on the planning of the internal spaces of a building.

Presented by

DR CHEAH CHEE BAN | SENIOR LECTURER, SCHOOL OF HOUSING, BUILDING AND PLANNING