건설안전역학

(1)

(Constructional Safety Mechanics)

토목안전환경공학과 안전트랙

옥승용

LN01: Introduction To Class (1)

(2)

• Quiz: 20%

• Mid-term Exam: 30%

• Final-term Exam: 40%

• Report: 5%

• Contribution(Attitude, Attendance, etc.): 5%

• Final grades are final. Absolutely no chance to change them by any excuse except for my mistakes.

• 강의 예절을 지켜주시기 바랍니다.

– The following activities are absolutely prohibited:

• Cellular Phone, Text Message, Restroom, Nodding

Evaluation

(3)

• Class Materials

– will be posted, when necessary, at the afore- mentioned website

• Textbooks

– 부교재

• Structural Analysis-

Using Classical and Matrix Methods

, written by Jack C. McCorMac, 4th Edition, Wiley & Son, Inc., 주식회사 동화 기술, 공역: 신수봉, 권순덕, 김성보, 이영 욱, 황재승, 김홍진,

• Structural Analysis, written by R.C. Hibbeler, 6th Edition in SI Units, Prentice Hall, 강영 종 외 4인 공역, Pearson Education

Preparations for Class

(4)

Class Schedule

Week Topics Remarks

01 Introduction to class (1) & (2)

02 Analysis of Truss Structures (1) Homework #01

03 Analysis of Truss Structures (2)

04 Analysis of Horizontal Beams (1) Quiz #01

05 Analysis of Horizontal Beams (2)

06 Analysis of Frame Structures (1) Quiz #02

07 Analysis of Frame Structures (2)

08 Mid-Term Exam

09 Deflection Computation by using Energy Method (1) 10 Deflection Computation by using Energy Method (2)

11 Deflection Computation by using Energy Method (3) Quiz #03 12 Analysis of Indeterminate Structures (1)

13 Analysis of Indeterminate Structures (2) Quiz #04

14 Analysis of Indeterminate Structures (3)

15 Final-Term Exam

(5)

학습내용

• Statics

– Rigid Body – Truss Structure

• Mechanics of Materials

– Deformable Body – Beam

• Constructional Safety Mechanics

– Deformable Body

– Truss, Beam and Frame Structures

(6)

Preliminary Study

 Equations of Equilibrium

 Free Body Diagram

 Support Conditions

(7)

Equations of Equilibrium ( 평형방정식 )

[Statics]

A structure or one of its members is in equilibrium when it

maintains a balance of force and moment.

0 0 0

 

z y x

F F F

0 0 0

 

z y x

M M M

3D Motion

0 0

0

x y z

F F M

 

2D Motion x

z

y

(8)

Free Body Diagram (자유물체도)

: 정적인 평형상태(Static Equilibrium)에 놓여 있는 구조물에 작용하는 외력(External Forces), 지점 반력(Support Reactions), 부재 내력(Internal Member Forces)을 표현한 선도

: 자유물체도에 표시된 모든 힘은 평형방정식을 만족(∵Static Equilibrium)

Internal Member Forces (부재내력)/(내력)/(부재력)

Reaction Forces (반력)

Support Reactions (지점반력) External Forces (외력)

(9)

Simple Example for FBD

10N

10N 10N

10N

(10)

Simple Example for FBD

10N

10N 10N

10N

(11)

10N

10N 10N

(12)

100N

5m

100N

100N Does it satisfy the equilibrium condition?

(13)

100N

How can we stop the rotation?

P

P' P

Does these approaches satisfy the equations of the equilibrium?

How can we stop the rotation, both satisfying the eqs. of eq.?

The only solution to this problem is

M

No!

(14)

100N

100N M

100N

100N M

M'

M' 100N

100N

(15)

100N

5m

100N 100N

Does it satisfy the equilibrium condition?

No! It rotates(moves).

Can the support resist the rotation?

No! It can’t stop the rotation due to the hinge condition.

How can we maintain the equilibrium state?

hinge

(16)

100N

5m

We should change the configuration of the structure,

by replacing the support with different one (removing the hinge).

100N

5m

hinge

or by modifying the configuration (adding member and support).

(17)

P 2

FBD for this new configuration

P 1 P x1

P y1

P x2

P y2

(18)

P 2

FBD for this problem?

P 1 P x1

P y1

P x2

P y2

M 1

M 2

(19)

More Examples for FBD