Introduction
③ Combination Joint
A
B
A：Rigid joint
C
D
B、D：Hinge joint C：Combination joint BF、CD Hinge joint，
E
F
G
BC、CF Rigid joint
3. Simplification of supports
长江三峡工程
Introduction
Introduction
上海南浦大桥
Introduction
Introduction
现代桥梁欣赏
Introduction
现代桥梁欣赏
Introduction
Introduction
中国民航飞机
Introduction
宇宙飞船
Introduction
Summary
Two words:
Simplification
Classification
Introduction
Fig.1 Main Teaching Building
Introduction
Fig.2
Introduction
Introduction
Introduction
Introduction
Introduction
Introduction
荷兰拦海大坝
Introduction
(1)、beam (2)、arch
(3)、truss (4)、rigid frame (5)、composite structure
梁
拱
桁架
刚架
组合结构
Introduction
1.4 Classifications of loads
(1) Duration of application : Dead load: dead load act on structure for ever. Its weight. Dead loads are those whose magnitudes remain constant and whose position doses not change. Live load: live load are those whose magnitude and position change. Live load contains movable load and moving load. Movable load are those which position can change: i.e. snow, person on structure. Furniture on a house. Moving load is meant by load can be moved by their own power. i.e. trolley of crane
结构 力 学
STRUCTURAL MECHANICS
武汉理工大学物流工程学院
普通高等教育“十一五”国家 级规划教材 Structural Mechanics 包世华主编
Textbook: 2006
References： 《结构力学教程》 龙驭求等主编，高等教育出 版社 2001 《结构力学》王重华主编， 人民交通出版 社 <<Structural Mechanics>> 支秉琛主编 清华大 学出版社
① in dimensions domain : Structures can be classified into plane stru. And space stru.
If members of the stru. are in a plane, its loads are also in the same plane .It is called plenary stru. If members are not in a plane or its loads are not lie in the same plane
（2）surface load：surface load can be simplified as concentrated load or line load。For example, wind, snow load, and equipment.
Introduction
1.2 Classification of structures
高速列车
Structural Mechanics Chapter 1 Introduction
Frame or member which carries the load is referred to as a structure in engineering. i.e.
① Crane’s jib;
Introduction
1.1 Computing Model
The following factors are taken into account: ① the width of the walls (b) is very small comparison with the length of the beam (l). ② The beam can’t move in horizontal direction because of friction between the beam and walls, but it can enlong or shrink (age) due to change of temperature. ③ the beam is represented by a line
② support frame of crane;
③ support frame of civil construction.
Introduction
To study the internal forces of the structure is the aim to this course. The structures in engineering are very complex (ity), so we must simplify the structures in several aspecction
Computing model
Introduction
truss workshop
CRANE
Introduction
How to simplify is a very important problem. We can do it from three aspects as following:
1. Simplification of Members


Introduction
2. Simplification of Joints
When the members are connected together, the mutual displacements of the members are restrained. The connection point is called joint .There are two types joint. ① Hinge Joint. (Small resistance in bending) A hinge joint restrains the translation of one member relative to the others , the members can have independent free rotations about the centre of the hinge ② Rigid Joint The members form a monolithic body, they can move and translate as a group, but can not move with respect to each other.
① Link support
Introduction

② Hinge Support

Introduction
③ Fixed support
A
HA
MA V A
④ Fixed direction support (定向支座)
Introduction
4、Simplification of load
（1）Body load：body load can be simplified as line-load. Dead load, for instance.
Introduction
(2) Manner of application: Static load: its magnitude, position and direction are not change. Dynamic load: give rise to vibration of structure.
Introduction ② In Restraints
Statically determinate stru.
Statically indeterminate stru.
Unstable stru.
Introduction
1.3 Plenary framed structures
Plenary framed structures can be divided into the following forms