FIELD OF STUDY: STRUCTURAL ENGINEERING

Transcription

1 FIELD OF STUDY: STRUCTURAL ENGINEERING

2 Faculty Members Asst. Prof. Dr. Mürüde Çelikağ Asst. Prof. Dr. Giray Özay Asst. Prof. Dr. Serhan Şensoy Asst. Prof. Dr. Masoud Negin Yarı zamanlı Prof. Dr. Ayşe Daloğlu Prof. Dr. Semih Küçükarslan

3 Compulsory Courses CIVL 211 Statics CIVL 222 Strength of Materials CIVL 343 Intro. Structural Mechanics CIVL 344 Structural Analysis CIVL 372 Fundamentals of Reinforced Concrete CIVL 473 Steel Structures CIVL 471 Design of Reinforced Conc. Structures Also AREA ELECTIVES

4 Structural engineering is the science and art of Planning Designing Constructing Structures that are Safe Serviceable Economical

5 Design Process

6 Design Process CIVL 372 Fundamentals of Reinforced Concrete CIVL 471 Design of Reinforced Concrete Structures

7 CIVL 211 Statics Design Process CIVL 372 Fundamentals of Reinforced Concrete CIVL 471 Design of Reinforced Concrete Structures CIVL 222 Strength of Materials CIVL 343 Int. Structural Mechanics CIVL 344 Structural Analysis

8 CIVL 211 Statics Design Process CIVL 372 Fundamentals of Reinforced Concrete CIVL 471 Design of Reinforced Concrete Structures CIVL 222 Strength of Materials CIVL 343 Int. Structural Mechanics CIVL 344 Structural Analysis CIVL 372 Fundamentals of Reinforced Concrete CIVL 473 Steel Structures CIVL 471 Design of Reinforced Concrete Structures

9 CIVL 211 Statics Design Process CIVL 372 Fundamentals of Reinforced Concrete CIVL 471 Design of Reinforced Concrete Structures CIVL 222 Strength of Materials CIVL 343 Int. Structural Mechanics CIVL 344 Structural Analysis CIVL 372 Fundamentals of Reinforced Concrete CIVL 473Steel Structures CIVL 471 Design of Reinforced Concrete Structures

10 What is Design? The calculation of the expected loads on the members of the structure and then the selection of suitable materials member sizes and shapes to resist the forces, moments, stresses and deflections calculated during analysis. Important: Design should comply with the relevant DESIGN CODES

11 What is Design? Good Structural Design is achieved through series of steps. These steps are not all necessary for every design. Structural Design requires experience, logical thinking, good understanding of structural behaviour and knowledge in the following areas: Other Branches of CE Materials Geotechnics (soil) Construction Technology Health and Safety Eng. Economics Computer Usage Mathematics Probability & Statistics CE Drawing Structural Eng. Branch Static, Dynamic, Strength of Materials Structural Analysis Structural Dynamics Design of Reinforced Concrete Design of Steel Design of Masonry etc. Structural Systems Structural Stability

12 How Do You Say That a Structure is Designed Up To Standard? Structural system and selected materials are suitable for the purpose of the building Itisstrong and stable enough to resist all the possible combination of ultimate - gravity dead and live loads - lateral wind loads - earthquake loads - accidental loads - blast loads It is stiff enough not to deform beyond the limiting design code values when subject to service loads. Safe for construction, daily use and maintenance Economic and preferably recyclable at the end of its life span

13 What are the factors effecting Loading Material Strength Structural Behaviour In real life it is not possible to predict the strength of any material or structure with absolute accuracy until it has been tested to destruction. Structural Safety? Some of the reasons are: The Statistical Meaning of Safety Variations in the weight and specification of materials Uncertainty in materials, loading, strength etc. External factors, such as weather conditions, how concrete was placed on site

14 Structural Systems Framed Structures Structural Frame, slab, beams, columns carry the loads to foundations Load Bearing Structures Walls carry the loads to foundations

15 Light Gauge Steel (EMU) Masonry Steel Structural Framing Materials Steel Wood Reinforced Concrete

16 Residential Commercial Structural Types Public Industrial Leisure

17 Bridges and Stadiums

18 Dynamics? Dynamics is the science of the forces involved in movement! Particles or rigid bodies are not at rest. In other words, they are not static. Newton s Second Law applies: F ma Suddenly applied forces or forces which are changing with time cause structures to vibrate!

19 Why do we have to study dynamics? Traffic loads on bridges Vibrating machines on structures Effect of blasting due to terrorist attacks Effect of wind force on structures Effect of Earthquakes etc.

20 What are the effects of wind force on structures? Wind cause impact load on structures Vortex induced oscillations (suspension bridges) Tacoma Narrows bridge (after collapse) Tacoma Narrows bridge (today) Failure of Tacoma Narrows Bridge on November 7, 1940 (picture from, Irvine 1999). Replacement of Tacoma Bridge (1950) (picture from Irvine, 1999).

21 How earthquakes effect structures? An earthquake is a spasm of ground shaking caused by a sudden release of energy in the Earth s lithosphere (i.e the crust+part of the upper mantle). Earthquakes result from the dynamic release of elastic strain energy that radiates seismic waves. Earthquakes typically result from the movement of faults, planar zones of deformation within the Earth's upper crust. eg. Reverse Fault: In a reverse fault, the block above the fault moves up relative to the block below the fault. This fault motion is caused by compressional forces and results in shortening. A reverse fault is called a thrust fault if the dip of the fault plane is small. [Other names: thrust fault, reverse-slip fault or compressional fault]

22 Inertia Forces in Structures Earthquake causes shaking of the ground. So a building resting on it will experience motion at its base. From Newton s First Law of Motion, even though the base of the building moves with the ground, the roof has a tendency to stay in its original position. But since the walls and columns are connected to it, they drag the roof along with them. This is much like the situation that you are faced with when the bus you are standing in suddenly starts; your feet move with the bus, but your upper body tends to stay back making you fall backwards!! This tendency to continue to remain in the previous position is known as inertia. In the building, since the walls or columns are flexible, the motion of the roof is different from that of the ground (Figure 1). (Ref. C.V.R.Murty Indian Institute of Technology Kanpur, Kanpur, India, May 2002) Figure 1: Effect of Inertia in a building when shaken at its base

23 Consider a building whose roof is supported on columns (Figure 2). Coming back to the analogy of yourself on the bus: when the bus suddenly starts, you are thrown backwards as if someone has applied a force on the upper body. Similarly, when the ground moves, even the building is thrown backwards, and the roof experiences a force, called inertia force. If the roof has a mass M and experiences an acceleration a, then from Newton s Second Law of Motion, theinertia force FI is mass M times acceleration a, and its direction is opposite to that of the acceleration. Clearly, more mass means higher inertia force. Therefore, lighter buildings sustain the earthquake shaking better. (Ref. C.V.R.Murty Indian Institute of Technology Kanpur, Kanpur, India, May 2002) Roof Column Foundation Soil Inertia Force Figure 2: Inertia force and relative motion within a building u Acceleration u

24 The inertia force experienced by the roof is transferred to the ground via the columns, causing forces in columns. During earthquake shaking, the columns undergo relative movement between their ends. In Figure 2, this movement is shown as quantity u between the roof and the ground.

25

26

27

28

29

30

31

32 How do we analyze/design structures subject to earthquakes? Conventional methods: Equivalent static load applied at floor levels Linear dynamic analysis (Response Spectrum Analysis) Recently developed methods: Nonlinear static analysis (pushover analysis) Nonlinear dynamic analysis

33 In which courses you will study dynamics and effects of dynamic forces on structures? Must courses: Dynamics Structural Design Area Elective Courses: Structural Dynamics Earthquake Resistant Design of Structures Other relevant courses