结构力学(双语)绪论
结构力学(英) Chapter2 Equilibrium and Geometric Stability PPT精品课件
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Statically Determinate Structures
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Shear Diagram
The equations of statics alone are sufficient to compute the reactions and the distribution of internal forces.
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＋ Mz = M1,z M2,z = 0
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Equilibrium of Planar Structure
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External Forces are the actions of other bodies to the structure under consideration.
n = number of structural components r = number of unknown reaction components If r = 3n, the structure is statically determinate If r > 3n, the structure is statically indeterminate
CH1 第一章 绪论(中英)
结构力学
计算模型的简化要点
材料性能的简化 混凝土 石头 钢材 钢筋混凝土
砖
木材
连续(continuous)
均匀(homogeneous) 各向同性(isotropic) 完全弹性或弹塑性(elastic or plastic)
结构力学
计算模型的简化要点
荷载的简化
重力，车轮压力 , 土压力, 水压力，地震 荷载，人群荷载，雪荷载，风荷载.. . 重力或者惯性力 车轮压力 , 土压力, 水压力，地震荷载， 人群荷载，雪荷载，风荷载.. .
竖向荷载
(c)
roof structure
屋架
基础
柱子
水平荷载
结构力学
桁架的计算模型
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结构力学
杆系结构的分类
梁(Beams) 拱(Arches) 桁架(Trusses)
板、壳和实体
结构力学
结构力学的研究内容
结构的合理组合（组成规律、合理形式和计算简图）
Rational configurations of structures
如何搭建一个结 构?
结构内力和位移的计算方法
Internal forces and displacements for structures
结构与基础间连接的简化 支座 supports
结构力学01第一章.绪论
壳式结构
通过壳体的形状和厚度 承受荷载，如穹顶、储
罐等。
荷载类型与特点
80%
永久荷载
长期作用在结构上的荷载，如结 构自重、土压力等。
100%
可变荷载
随时间变化而变化的荷载，如楼 面活荷载、风荷载、雪荷载等。
80%
偶然荷载
不常出现但一旦出现将对结构产 生重大影响的荷载，如地震力、 爆炸力等。
结构安全性与经济性
跨学科融合
与建筑学、土木工程、机械工程等学 科交叉融合，推动结构力学领域的发 展和创新。
04
结构力学在土木工程领域应用
建筑设计阶段应用
结构分析和设计
利用结构力学原理和方法，对建 筑结构进行受力分析和设计，确 保建筑物在各种荷载作用下的稳 定性和安全性。
优化设计方案
通过结构力学计算和分析，可以 对建筑设计方案进行优化，提高 建筑物的结构性能和经济效益。
国外研究现状
在结构优化设计、新材料应用等方面较为领先，注重创新性和实 用性。
未来发展趋势预测
计算方法创新
发展更高效、精确的计算方法，如有 限元法、离散元法等。
新材料应用
探索新材料在结构力学中的应用，提 高结构性能和耐久性。
智能化发展
结合人工智能、大数据等技术，实现 结构力学设计、分析的智能化和自动 化。
结构力学01第一章绪论
目
CONTENCT
录
• 绪论引言 • 结构力学基本概念 • 结构力学发展历史及现状 • 结构力学在土木工程领域应用 • 结构力学分析方法简介 • 结构力学实验方法及设备介绍
01
绪论引言
课程介绍
结构力学是固体力学的一个分 支，主要研究工程结构受力和 传力的规律，以及如何进行结 构优化的学科。
结构力学英文课件Chapter 1 Introduction2
1.3.2 simplifying point of analytical model
(1) The simplification of structural system Generally ,the actual structures are space, or three-dimensional, structures, whose members are connected as a space frame to undergo the loadings likely acting on it in various sense. Fortunately ,many actual three-dimensional structures can be subdivided, by discarding some subsidiary space restraints ,into plane structures for simplifying analysis. The book will mainly discuss the calculation problems of plane structures. (2) The simplification of members The main attention the book focuses on is the framed structures. A framed structure is comprised of members, whose crosssectional dimensions is much smaller than the length l.
第1章 结构力学绪论
1. 概念：将实际结构进行抽象和简化，使之既能反映实 际工程的主要受力和变形特征，同时又能使计算大大简 化。这种经合理简化，用来代替实际结构的力学模型叫 做结构的计算简图。 2. 简化原则
（1）计算简图要尽可能反映实际结构的主要受力和变形 特点，使计算结果安全可靠； （2）略去次要因素，便于分析和计算。
一、平面杆件结构的分类
1. 梁 梁是一种受弯构件，轴线常为一直线，可以是 单跨梁，也可以是多跨连续梁，其支座可以是铰支座、 可动铰支座，也可以是固定支座。如图10(a)为单跨梁， 图10(b)为多跨连续梁。
2. 拱 拱的轴线为曲线，在竖向力作用下，支座不仅 有竖向支座反力，而且还存在水平支座反力，拱内不仅 存在剪力、弯矩，而且还存在轴力。图10(c)所示为一两 铰拱。
（2）按杆件系统的轴线是否在同一平面内分：
平面结构 : 杆件系统的轴系在同一平面内，且外力也作用在该平面内 空间结构 : 杆件系统的轴系不在同一平面内，外力也作用在任意平面
（3）按内力是否静定分：
静定结构 :内、反力可由静力平衡条件求出 超静定结构 :由静力平衡和变形条件共同求解
二、课程的主要研究对象
3. 根据荷载位置的变化情况，荷载可分为固定荷载 和移动荷载。 固定荷载是指荷载的作用位置固定不变的荷载，如 所有恒载、风载、雪载等； 移动荷载是指在荷载作用期间，其位置不断变化的 荷载，如吊车梁上的吊车荷载、钢轨上的火车荷载等。
4. 根据荷载的作用性质，荷载可分为静力荷载和动 力荷载。 静力荷载的数量、方向和位置不随时间变化或变化 极为缓慢，因而不使结构产生明显的运动，例如结构的 自重和其它恒载； 动力荷载是随时间迅速变化的荷载，使结构产生显 著的运动，例如锤头冲击锻坯时的冲击荷载、地震作用 等。
结构力学 第1章 绪论
2. 根据荷载的分布范围，荷载可分为集中荷载和分 布荷载。 集中荷载是指分布面积远小于结构尺寸的荷载，如 吊车的轮压，由于这种荷载的分布面积较集中，因此在 计算简图上可把这种荷载作用于结构上的某一点处。 分布荷载是指连续分布在结构上的荷载，当连续分 布在结构内部各点上时叫体分布荷载，当连续分布在结 构表面上时叫面分布荷载，当沿着某条线连续分布时叫 线分布荷载，当为均匀分布时叫均布荷载。
一般可取纵向边框架、纵向中框架、横向边框架和 横向中框架共四榀作为计算单元。 由于现浇整体式框架结构的梁柱结点是现浇成整体 的，纵梁和横梁的梁端弯矩可通过该结点进行传递和分 配，所以该结点一般认为是刚结点 刚结点。柱下端一般与基础 刚结点 整体浇注在一起，可简化为固定支座 固定支座，见图9(b）、(c)。 固定支座
一、计算简图的概念和简化原则 1. 概念：将实际结构进行抽象和简化，使之既能反映实 际工程的主要受力和变形 受力和变形特征，同时又能使计算大大简 受力和变形 化。这种经合理简化，用来代替实际结构的力学模型 力学模型叫 力学模型 做结构的计算简图 计算简图。 计算简图 2. 简化原则 （1）计算简图要尽可能反映实际结构的主要受力和变形 特点，使计算结果安全可靠； （2）略去次要因素，便于分析和计算。
5 ．荷载 荷载的简化 荷载 荷载的简化是指将实际结构构件上所受到的各种荷 载简化为作用在构件纵轴上的线荷载、集中荷载或力偶。 在简化时应注意力的作用点、方向和大小。 6 ．材料性质 材料性质的简化 材料性质 在力学计算中一般都把各构件材料假设为均匀、连续、 各向同性、完全弹性或弹塑性的，但对于混凝土、钢筋 混凝土、砖、石等材料有一定程度的近似性。
3. 刚架 刚架由梁、柱组成，梁、柱结点多为刚结点， 柱下支座常为固定支座，在荷载作用下，各杆件的轴力、 剪力、弯矩往往同时存在，但以弯矩为主。如图10(d)所 示。 4. 桁架 由若干杆件通过铰结点连接起来的结构，各 杆轴线为直线，支座常为固定铰支座或可动铰支座，当 荷载只作用于桁架结点上时，各杆只产生轴力，如图10(e) 所示。 5. 组合结构 即结构中部分是链杆，部分是梁或刚架， 在荷载作用下，链杆中往往只产生轴力，而梁或刚架部 分则同时还存在弯矩与剪力，如图10(f)所示。
(完整word版)结构力学讲义
第一章绪论§1.1 结构和结构的分类一、结构(structure)由建筑材料筑成，能承受、传递荷载而起骨架作用的构筑物称为工程结构。
如：梁柱结构、桥梁、涵洞、水坝、挡土墙等等.二、结构的分类：按几何形状结构可分为：1、杆系结构(structure of bar system) :构件的横截面尺寸<<长度尺寸；2、板壳结构（plate and shell structure) ：构件的厚度〈〈表面尺寸。
3、实体结构（massive structure）：结构的长、宽、厚三个尺寸相仿。
三、杆系结构的分类：按连接方法，杆系结构可分为：§1.2 结构力学的研究对象、任务和方法一、各力学课程的比较：二、结构力学的任务：1、研究荷载等因素在结构中所产生的内力(强度计算）；2、计算荷载等因素所产生的变形（刚度计算);3、分析结构的稳定性（稳定性计算）；4、探讨结构的组成规律及合理形式。
进行强度、稳定性计算的目的，在于保证结构满足安全和经济的要求。
计算刚度的目的，在于保证结构不至于发生过大的变形，以至于影响正常使用。
研究组成规律目的，在于保证结构各部分，不至于发生相对的刚体运动，而能承受荷载维持平衡。
探讨结构合理的形式，是为了有效地利用材料，使其性能得到充分发挥。
三、研究方法：在小变形、材料满足虎克定律的假设下综合考虑：1、静力平衡;2、几何连续；3、物理关系三方面的条件,建立各种计算方法。
§1.3 结构的计算简图（computing model of structure )一、选取结构的计算简图必要性、重要性：将实际结构作适当地简化，忽略次要因素，显示其基本的特点。
这种代替实际结构的简化图形,称为结构的计算简图。
合理地选取结构的计算简图是结构计算中的一项极其重要而又必须首先解决的问题。
二、选取结构的计算简图的原则：1、能反映结构的实际受力特点，使计算结果接近实际情况.2、忽略次要因素，便于分析计算。
浅谈《结构力学》的双语教学
浅谈《结构力学》的双语教学结构力学是一门广泛的学科，许多分支，涉及工程学、物理学、材料学和数学等多个领域的基础理论和应用研究，它以力学作为基础，将结构力学应用于建筑工程、机械工程和交通工程等，成为许多应用工程学科的重要理论研究和分析工具，广泛应用于工程设计、制造、运行和管理中。
在发展现代科技和工程设计过程中，结构力学发挥着越来越重要的作用，但是，传统的教学方式对于学生来说无法很好地让学生理解结构力学的基础原理，学习成绩也不是太理想。
为了解决这个问题，我使用了双语教学的方法，让学生能够更快速地理解和运用结构力学的基础原理，让他们能够更好的掌握这门学科。
一、双语教学的优势双语教学以两种语言（外语和本地语言）结合教学，有以下优势： 1、改善学习效果。
双语教学可以让学生用两种语言同时获得信息，使他们能够更好地理解语言及其附带的意义，让学习更加有效。
2、增强语言表达能力。
学习者可以使用另一种语言来表达自己的思想，这样可以增强学生的语言表达能力。
3、提高对知识的认知能力。
学习者也可以使用另一种语言来理解知识，使他们能够更深入地理解结构力学的原理和概念，从而提高其对知识的认知能力。
二、双语教学实施过程双语教学的实施过程主要是这样的：1、预习活动。
在此活动中，学生根据教师准备的英文读物，课前对重点内容进行概括和理解，这样可以帮助学生提高对结构力学的基本概念的理解。
2、混合类(英-汉)授课。
在此活动中，教师使用英文教材，以汉语为主，搭配英文解释，让学生能够边听边理解英文的内容，让他们能够更好地理解英文中的内容及其附带的意义，从而加深对结构力学的学习。
3、主动参与类活动。
在此活动中，学生可以使用英文表达自己的思想，可以用英语进行讨论和解答问题，这样可以让学生更好地理解结构力学的基本原理，并且提高他们的语言表达能力。
三、双语教学的督导机制1、建立有效的督导机制。
双语教学的督导机制必须有目标、过程评估和结果评估等内容。
结构力学Chapter_1_Introduction
Chapter 1 IntroductionContents§ 1-1 Main objectives and primary tasks of structural mechanics (1)§ 1-2 Analytical model and line diagram (2)§ 1-3 Classification of structures and loads (9)1-3-1 Classification of structures (9)1-3-2 Classification of loads (10)§ 1-4 Basic assumptions (11)Problems (15)§ 1-1 Main objectives and primary tasks of structural mechanicsA structure refers to a system of load carrying/transferring components that frame engineering buildings of various types of occupancy. Typical examples of structures include, but not limited to, the frames formed by floor slabs, beams, columns, shear walls and foundations, etc., of residential constructions, dams and flood gates of hydraulic constructions, bridges, tunnels and culverts of highways and railways, and the load carrying frames of automobiles and aircrafts, etc.The mechanical properties and load carrying capacity of engineering structures are closely linked to their geometric characteristics, based on which general structures can be divided into three categories:(1) Skeletal structures, which are consisted of a certain number of interconnected skeletal members. The geometric characteristic of a skeletal member is that its cross-sectional dimension is much smaller than its length. Typical examples of skeletal members and structures include beams, rigidly connected frames, arches and trusses, etc.(2) Plate and shell structures, which are also referred to as thin-wall structures. The geometric characteristic of a thin-wall structure is that its thickness is much smaller than the other two dimensions of it. The floor slabs, hemispherical roof diaphragms (Figure 1-1) and the shells of plane fuselage and ship hull all fall into this category.(3) Solid structures, also known as three-dimensional continuum structures, of which the length, width, and height are in similar size. Gravity retaining walls (Figure 1-2) and gravity dams of hydraulic constructions are examples of solid structures.Figure 1-1 Figure 1-21- 1Structural mechanics is mainly focused on the study of reasonable configuration of structures and their performance in regard to the internal forces, deformation, dynamic responses and stability when under external loads and/or other external effects, such as support movements and temperature changes. The objective of the study is to make the structures to meet the requirements for safety, serviceability and economic issues. More specifically, the primary tasks of structural mechanics include the following aspects:(1) Establish a rational form for a structure considering the functional requirements and occupancy of the structure.(2) Investigate the theories and methods of calculation of the internal forces, deformation, dynamic responses and stability of the structures.(3) Investigate the theories and methods of determination of the external actions based on the structural responses, and vice versa, and those of control of structural responses.Structural mechanics is an important professional basic course of the discipline of civil engineering. It is closely linked with several prerequisite courses, including theoretical mechanics and mechanics of materials, and the subsequent elastic and plastic mechanics. The theoretical mechanics and mechanics of materials are considered as fundamental mechanics while structural mechanics is mostly focused on skeletal structures and therefore is sometimes referred to as special structural mechanics; while the elastic and plastic mechanics mostly deals with continuum structures and plate and shell structures.Advances in modern engineering technologies and rapid development of computer technologies have had a profound impact on the discipline of structural mechanics. On one hand, analysis of massive engineering structures under actions of complex external factors requires emphasizing the integrated application of basic concepts of structural mechanics and theories of conceptual engineering design. On the other hand, the rapid increase in computing capacity requires the development of compatible theories and methods of structural mechanics. As a result, the traditional structural mechanics has been boosted towards directions, including the conceptual structural mechanics and computational structural mechanics.Many fundamental changes have taken place in the roles and functions of scientific and technical personnel in the field of civil engineering due to the fast development of science and technologies. The teaching of structural mechanics should therefore focus on the basic concepts of mechanics and their rational applications, in conjunction with the cognitive rules of the objective world and context of engineering practice, and eventually aims at improving the qualities and abilities of the students as an essential goal.§ 1-2 Analytical model and line diagramIn the real sense, the load state of a structure is often very complex. It will be difficult while unnecessary in many cases to analyze the structures in full accordance with the actual states of them, and thus certain simplifications and assumptions need to be made before analyzing the structural responses. Often, during the analysis some 1- 2secondary factors of actual structures are ignored under the premise that the structural responses can still be reflected correctly. Such a simplified representation of an actual structure for structural analysis purposes is called an analytical model. In analysis of mechanics, an analytical model is representative of the actual structure. Therefore, it is a key issue and should be solved first to choose and establish a rational analytical model.The principles of selection of an analytical model include as following:(1) Retain the main factors and omit the secondary factors so that the analytical model can reflect the essential features of the structural responses, such as internal forces.(2) To simplify the analytical model as much as possible without affecting its feasibility for structural analysis.In addition, different analytical models can be used for the same structure based on the requirements and specific circumstances. For example, in the preliminary design of a structure, a relatively coarse analytical model can be used; while in the construction design, a more precise analytical model should be used. Simplified analytical models can be used for hand computation while more precise analytical models can be constructed for computerized calculation. For dynamic analyses, the analytical models can be more simplified since the analysis is often complicated and time-consuming, while for static analysis, more precise analytical models can be used as the calculation is simple and fast.An analytical model comprises simplification of actual structures in many aspects and will be introduced separately as following.1. Structural configurationsSkeletal structures can be further divided into plane and spatial skeletal structures. Generally, all actual structures are spatial structures since they need to resist loads from all directions. However, in most cases, spatial constraints that are secondary to the structural performance can often be ignored or converted into one plane, by which an actual structure can then be broken down into several plane structures. In such way, the structural analysis can be greatly simplified.2. Structural members: line diagramsMembers of a skeletal structure can normally be represented by lines coinciding with their centroidal axes. The lengths of the members are expressed as the distances between the intersection points of them and adjacent members.3. ConnectionsA connection refers to the intersection amongst the members. Although the detailed configurations of the connections of timber, steel and concrete structures are quite different, their analytical models can normally be classified into two types:(1) Pin (hinge) connectionsThe characteristic of a pin connection is that all connected members can rotate freely around the connection, and therefore it is normally represented by an idealized smooth hinge. This idealized connection, however, is very difficult to achieve in practical engineering. For example, speaking of the intermediate connection of the bottom chord of a timber roof truss, as shown in Figure 1-3a, it is apparent that the1- 3Figure 1-4a shows the details of a connection between a side column and a beam of a reinforced concrete multistory frame structure. Since the concrete of the side column and beam are cast monolithically and the reinforcing bars extend into the column no less than the required anchorage length, it is ensured that the beam and the column are firmly linked together. In this case, the connection is considered as a rigid connection and its analytical model is shown in Figure 1-4b.4. SupportsA support refers to the connection between a structure and the foundation. The loads applied onto a structural are eventually passed via supports to the foundation and soil underneath. The counterforces passed from the supports to the structure are referred to as reaction forces. For plane structures, there are mainly five types of supports:(1) Roller supportExamples of roller supports include roller bearing (Figure 1-5a) and roll shaft bearing (Figure 1-5b) used in bridges.1- 4(4) Sliding supportFigure 1-8a shows schematically a sliding support (also known as a directional pin support). This type of support limits the rotation and movement along one direction while allows sliding in the other direction of the support. For example, the structure shown in Figure 1-8a cannot rotate or move vertically at the support while it can have a small amount of sliding along the horizontal direction. This type of support1- 5(5) Elastic supportAn elastic support is used when the deformation of the support cannot be ignored for structural analysis purposes. Shown in Figure 1-9a is a bridge deck structure, for which the deck loads are passed through the longitudinal beams to the horizontal beams and girders, and eventually to the piers of the bridge. In the load transfer path, the horizontal beams support the longitudinal beams and the resulting deformation of the horizontal beams may lead to vertical displacements of the longitudinal beams. In this case, each of the horizontal beams is equivalent to a spring support to the longitudinal beams. Since this type of supports has certain ability to resist transverse movements, they are referred to as an anti-sliding elastic support. For example, the intermediate supports of the longitudinal beam shown in Figure 1-9b all fall into this category. Another type of elastic supports has certain ability to resist torsional movements, known as anti-rotation elastic support.1- 65. LoadsThe floor loads of engineering buildings can generally be simplified as uniformly distributed vertical load; the lateral wind load can be simplified along the height of the buildings as uniformly distributed (in several segments), and so on.To illustrate the process of simplification of structural loads, a single story reinforced concrete industrial workshop, as shown in Figure 1-10, is used as an example. Normally, a reinforced concrete industrial workshop is spatial and consists of roof trusses, roof sheathing panels, columns, crane beams and bracing system, etc. Vertical roof loads are passed first from the sheathing panels to the roof trusses, and then to the columns at both ends of the trusses, and eventually to the foundation. When the workshop is subjected to lateral wind loads, the loads on the roof sheathing panels will be transferred to the upper ends of the columns via roof trusses; while the wind loads on the sidewalls are generally simplified as uniform distributed loads and are transferred to the columns via the walls and eventually to the foundation. When these two types of loads act separately, all plane frames (comprising trusses and columns) except those at the sides of the workshop will generate almost the same internal forces and deformation; therefore, the structural analysis of the building can be based on the analysis of one of these plane frames. Thus, a spatial problem can be simplified to a plane problem. It is well known that the longitudinal connections (mostly achieved by bracings) of the workshop is relatively weak and cannot provide sufficient integrity. Therefore, when the workshop is subjected to vertical or horizontal crane loads, it is conservative to assume that all or a certain percentage of the crane loads are resisted by the frame right underneath the crane(s). Thus, the workshop can still be analyzed as a plane system.1- 71- 8 Figure 1-10 1Fixed steel skylightRibbed sideboard Sheathing panel ColumnWindowBeamDitch Exterior wall LintelSteel bracketCullis board CranebeamGround Concrete padCup-shaped foundation Crane ladderWind column§ 1-3 Classification of structures and loads1-3-1 Classification of structures2. ArchesNormally the centroidal axis of an arch is curved. Arches will have horizontal reaction force under vertical loads, which helps to reduce the bending moments on the cross-sections (Figure 1-13).1- 93. Rigid framesA rigid frame usually consists of straight members. Its configuration is characterized by rigid connections at intersections of members (Figure 1-14). Sometimes a rigid frame is also called a frame.Figure 1-13 Figure 1-144. TrussesTrusses consist of straight members, which are all pin-connected. When a truss is subjected to nodal forces only, there will be only axial forces in truss members (Figure 1-15).5. Composite structuresA composite structure comprises truss members and beams (Figure 1-16a), or truss members and rigid frame members (Figure 1-16b). The feature of its load state is that its truss members only take axial force and all the other flexural members can resist axial force, shear force and bending moments simultaneously.In addition to the five types of skeletal structures mentioned above, which are the most basic, there are more complex ones, such as suspension cable structures.Figure 1-16Skeletal structures can be plane or spatial. When the centroidal axes of the members and the applied loads are in the same plane, it is known as a plane skeletal structure, or simply a plane structure. Those do not meet these conditions are known as spatial skeletal structures, or simply spatial structures (see § 3-6).1-3-2 Classification of loadsLoads refer to the external forces acting on a structure. For example, the 1- 10self-weight of a structure, crane loads of industrial workshops, loads from cars driving on a bridge, soil or water pressure acting on hydraulic structures, and so on.The various types of loads can be briefly classified as follows based on their duration and nature:1. Classified based on duration of load(1) Dead loadsLoads that act permanently on a structure of constant magnitudes and fixed positions are known as dead loads. For example, the self-weight of a structure and the weight of the devices that are permanently attached to the structure. A dead load does not change in terms of its magnitude, position and direction during the service life of a structure.(2) Live loadsA load of a variant magnitude and only temporarily acts on a structure is known as a live load. Examples include loads caused by train and cranes, people, wind, snow and so on. In structural analysis, usually dead loads and some live loads (such as people, wind and snow loads) are considered as fixed in terms of their position, and are therefore called as fixed loads. Some live loads, such as loads brought by cranes, cars and trains, are referred to as moving loads since their positions on a structure are variable.2. Classified based on the nature of loads(1) Static loadsStatic loads have constant magnitudes, positions and orientations over time, and are normally assumed to be increased gradually from zero to a sustained value. Consequently, the mass of a structure under static loading will not produce apparent acceleration and inertia forces, and thus will not cause vibration of the structure. Self-weight of structures and other dead loads all belong to static loads.(2) Dynamic loadsDynamic loads change rapidly over time. The structures under dynamic loads will generate apparent acceleration and corresponding inertia forces, which will subsequently cause structural motion or vibration. For example, loads caused by eccentric masses of a running machine, dynamic actions on structures caused by ground motion during an earthquake, impact actions from waves on hydraulic structures, blast waves from an explosion, fluctuating loads caused by wind, and so on, all belong to dynamic loads.§ 1-4 Basic assumptionsIn addition to various simplifications made in construction of analytical models of structures, structural analysis can also be simplified by taking assumptions of the structural behavior based on the actual situations.Structural mechanics usually considers the following three basic assumptions:(1) Structures are continuous and remain so when subjected to external loading.(2) Hooke’s Law applies, which states that, for a structure in static equilibrium, the displacement u at any point (Figure 1-17) can be expressed asn n F a F a F a u P P P +++=L 2211 (1-1)where a1, a2… and a n are constants and independent of the loads F P1, F P2... and F Pn; however, the constants are normally different for displacements of different points on the structure and different positions and orientations of the external loadings.(3) A structure recovers its original unstressed state if all external loads are withdrawn.The structures that are analyzed based on these three assumptions are known as linear elastic structures. At year 1859 Kirchhoff proposed the uniqueness theorem of solution of elastic systems, according to which the elastic deformation of a linear elastic system has unique relationship with the external loads, i.e., the internal force and deformation of a linear elastic system are uniquely determined given the external loading actions. The theorem of uniqueness of solution of linear elastic system plays an important role in structural analysis. A structural analysis based on this theorem is known as a linear analysis.Figure 1-18The principle of superposition of linear elastic structures can be proved based on the assumptions (2) and (3), i.e., Equation (1-1) applies to a series of load vectors F P1, F P2... F Pn not only when they are at a constant ratio but also when they are in arbitrary ratios to each other. In other words, the applicability of Equation (1-1) is independent of the loading sequence, so are the constants a1, a2…and a n. The principle of superposition plays an important role in structural analysis of linear elastic structures.Besides, some other important theorems, such as the reciprocal theorem (see §5-7), can also be derived from the three basic assumptions.In real engineering practice, some structures do not meet the basic assumptions. Such structures are known as nonlinear structures. The analysis of such structures is called a non-linear structural analysis. The nonlinearity in structural behavior mainly comes from the nonlinearity in material behavior and geometric characteristics of the structures.The so-called material nonlinearity refers to the physical properties of structural materials in case they are nonlinear, including nonlinear elastic and plastic. For example, as shown in Figure 1-18, the material near the midspan (with the shadowed area) of a simply supported steel beam can exhibit nonlinearity when the loadbecomes large. In this case, the relationship between the internal forces, deformation and the external loading becomes nonlinear.The so-called geometric nonlinearity refers to the phenomenon that the deformation or displacement of a structure gets so large that the equilibrium conditions can only be applied based on the deformed configuration of the structure. Figure 1-19a shows an eccentrically compressed column. When the translational displacement, Δ, of the upper end of the column is small compared to the loadeccentricity e, the equilibrium conditions can be applied to the original configuration of the column without causing too big errors. Consequently, the bending moment at the bottom end of the column, M A, is considered to be equal to F P e. Otherwise, if Δ is large compared to the load eccentricity e and cannot be ignored, the equilibrium conditions must be established based on the deformed column configuration, i.e., M A=F P(e+Δ). Since the translational displacement Δ is a function of F P, both thedeformation and internal forces of the column will be nonlinear.Another example is shown in Figure 1-19b, where the structure reaches equilibrium under an external load applied at point A. The deformed configuration is represented by dashed lines. Since the displacement is quite large compared to the dimension of the structure, the equilibrium equations for the calculation of the internal forces of the two tension rods must be constructed based on the deformed configuration. Since the deformed configuration of the structure is dependent on the external loading, the deformation and internal forces are also nonlinear with the external loading.Figure 1-19c shows a curved bar subjected to a vertical load. The support conditions of the curved bar are dependent on its deformation. This nonlinearity in boundary conditions can also be regarded as geometric nonlinearity. In fact, the force equilibrium is always reached on the deformed configuration of a structure no matter how big the structural deformation or displacement is. It is only that ignoring the difference between the deformed and original configurations of a structure will not cause significant errors when the structural deformation or displacement is small enough.Figure 1-19For nonlinear structures the theorem of unique solution and the principle ofFor most actual structures, the stress-strain relationship of the materials will be close to (for example steel structures) or can be approximately considered (frame example reinforced concrete structures) as linear. Meanwhile, the structural deformation and displacement will be quite small compared to the dimension of the structure. In this case, the three basic assumptions hold and the theorem of unique solution and the principle of superposition apply. Chapters 1 to 10 of this book will mainly discuss the linear elastic structural analysis.Problems[1-1]What are the major differences in the geometric configurations of skeletal structures, plate and shell structures and continuum structures?[1-2]What are the basic tasks of structural analysis and the major problems that should be paid attention to during the study of structural mechanics?[1-3]What is the analytical model of a structure? How to choose an analytical model?[1-4]What is the major difference and possible relationship between moving loads and dynamic loads?[1-5]What is a linear elastic structure and what are the basic characteristics of the structural behavior of linear elastic structures? What is the basic meaning ofHooke's law?[1-6]What are the basic characteristics of structures with material nonlinearity and geometric nonlinearity?。
结构力学第一章绪论
➢ 梁、刚架、拱
➢ 按结构计算特点分
➢ 静定、超静定
➢ 按结构几何特性分
➢ 平面、空间
Y. Peng, Dept. of Civil Engineering & Architecture, Southwest University of Science & Technology
➢ 反力Fy必垂直于支承面且通过铰中心
A
A
支座 垫板
Fy
Fy
2、 固定铰支座
➢ 只允许绕铰转动，忽略磨擦
➢ 反力作用线过铰心
➢ 用坐标分力Fx，Fy表示
A
梁 圆柱形铰 滚轴
梁
圆柱形铰
支座 垫板
Y. Peng, Dept. of Civil Engineering & Architecture, Southwest University of Science & Technology
3、 固定支座
➢ 既不能转动，也不能移动。 ➢ 水平反力Fx，竖直反力Fy，反力矩M
Fx M Fy
Y. Peng, Dept. of Civil Engineering & Architecture, Southwest University of Science & Technology
4、 定向支座
1.4 荷载的分类
主动力
外力
力
约束力
内力
荷载 反力
➢ 按作用在结构上的时间长短分
➢ 恒载、活载
➢ 按作用在结构上的分布情况分
➢ 分布荷载、集中荷载
➢ 按作用在结构上的动力效应分
➢ 静荷载、动荷载
Y. Peng, Dept. of Civil Engineering & Architecture, Southwest University of Science & Technology
结构力学绪论范文
结构力学绪论范文结构力学是一门研究物体受力和变形的学科，它是现代工程学的重要基础学科。
结构力学的发展与工程实践密切相关，它对于工程结构的设计、分析和优化起着至关重要的作用。
因此，学习结构力学不仅仅是理论性的培养，更是一种实践能力的提升。
结构力学主要研究的对象是各种材料的受力和变形情况。
在工程实践中，结构承受的力有静力和动力两种情况，而变形也分为弹性和塑性两种情况。
弹性变形是指材料在受力后可以恢复到原来的形状，而塑性变形则是指材料在受力后会永久改变形状。
了解材料的受力和变形情况对于工程结构的设计和计算至关重要。
结构力学的研究方法包括了理论分析、实验测试和数值计算三种。
理论分析是通过基于力学原理和数学方法来解决结构受力和变形问题的手段，它可以达到较高的精度和准确性。
实验测试则是通过设计和实施一系列实验来观察结构的受力和变形情况，它可以验证理论分析的结果。
数值计算是利用计算机辅助进行结构的力学分析，它可以处理复杂的结构和大量的数据，提高工程计算的效率和准确性。
结构力学的应用范围非常广泛，几乎涵盖了所有的工程领域。
在土木工程中，结构力学被广泛应用于桥梁、隧道和建筑物等工程结构的设计和计算。
在航天工程中，结构力学可以用于分析火箭和卫星等航天器的受力和变形情况。
在机械工程中，结构力学可以用于分析和设计各种机械设备的受力和变形情况。
在电子工程中，结构力学可以用于分析和设计各种电子设备的受力和变形情况。
总之，结构力学在各个工程领域都扮演着重要的角色。
结构力学的研究不仅仅是为了解决实际工程问题，更是为了深入理解材料的力学行为和物理性质。
通过对结构力学的研究，可以提高人们对材料的认识和理解，为新材料的开发和应用打下基础。
结构力学的研究还可以优化结构的设计和节约材料的使用，提高工程的经济性和可持续性发展。
最后，我们要明确结构力学的研究方法和应用领域。
结构力学需要通过理论分析、实验测试和数值计算相结合的方式进行研究，以获得较为准确和可靠的结论。
结构力学 第一章 绪论
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纵向荷载下
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§1-3 杆件结构的分类
高层建筑、 大型水利工程、 桥梁结构、 大跨结构 高耸结构、 核电站结构、 体育馆结构。
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框架结构
悬索桥（悬索）
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体育馆（板、壳结构）
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上海杨浦斜拉桥
世界第一拱——卢浦大桥
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1-2-2 结构计算简图的概念
y
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FAy
用于大型钢桥
图1-7 可动铰支座及反力
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固定端(固定支座)
限制全部位移 ( 移动和转动 ) ，其反力用沿 坐标的分量和力偶来表示。
y A x
y Ayx NhomakorabeaFAx
MA
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图1-8
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定向支座
限制某些方向的位移和转动，而允许某一 方向产生位移，其反力除所限制位移方向力外， 还有支座反力偶。 y
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1-2-4 杆件的简化
在计算简图中，结构的杆件就可抽象化地用 轴线来表示。
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1-2-5 结点的简化及分类
结点 (Joint) 杆件的交汇点。
结点可分为铰结点、刚结点和组合结点。
结构力学STRUCTURALMECHANICSppt课件
3.拱
4.刚架
5.组合结构
平面结构和空间结构
RA
RB
y x
y
x z
-8-
§1-4
荷载的分类
１、根据荷载作用时间长短：恒载、活载。 ２、按荷载作用的性质：静力荷载、动力荷载。
-9-
结构力学的任务:
(1)组成规律与合理形式,计算简图的合理选择； (2)内力与变形的计算方法.强度和刚度；
(3)稳定与动力反应。
结构力学的内容(从解决工程实际问题的角度提出) (1) 将实际结构抽象为计算简图； (2) 各种计算简图的计算方法； (3) 将计算结果运用于设计和施工。
结构力学的研究对象：平面的杆系结构。
1 绪论 2 结构的几何组成分析 3 静定结构内力计算 4 静定结构位移计算
8 9
影响线 矩阵位移法
10 结构的动力计算 11 结构的极限荷载 12 结构的稳定计算
5 力法
6 位移法 Байду номын сангаас 力矩分配法
结构力学的学习方法
研究性学习
先修课,公式,定理,概念,作业。 结合工程实际思考问题
§1-2 结构的计算简图
结构力学
-1-
第一章
绪
论
§1-1 结构力学的任务和学习方法
结构的定义: 建筑物中支承荷载而 起骨架作用的部分。 结构的几何分类: (1)杆件结构 (2)板壳结构 (3)实体结构
结构设计过程与步骤: (1)选择合理承重体系及构件几何尺寸；
(2)引入简化假定，取计算简图，进行结构分析； (3)依据结构分析结果，进行结构设计和构造处理。
换言之：铰结点可以传递力， 但不能传递弯矩。
4.支座的简化 (1) 铰支座 (2) 滚轴支座 (3) 固定支座
结构力学第一章 绪论和构造分析
一、确定计算简图的原则 （1） 从实际出发——计算简图要反映结构的主要性能。 （2）分清主次,略去细节——计算简图要便于计算。
二、 计算简图的简化要点 1.结构体系的简化
多数情况下，可以忽略一些次要的空间约束，将实 际空间结构分解为平面结构。
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5、思考题
1. 杆件结构、板壳结构与实体结构的主要差别是什么？
2. 结构力学、材料力学、弹性力学的研究对象的主要 差别是什么？
3. 常见的雨伞、降落伞和气球各属于那种（张拉式薄 膜结构充气式薄膜结构）薄膜结构？
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§1-2 结构的计算简图
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重庆长江大桥
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斜拉结构－上海南浦大桥
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3. 自学能力 • 复习已学的知识——即精读教材； • 摄取新的知识——即阅读参考书; • 理解、分析、概括、整理、运用所学知识。
4. 表达能力 • 作业条理清楚，步骤整齐，计算书书写整洁。
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Some examples of structures
结构力学的主要研究对象是杆件结构 The main objective of structural mechanics is framed structures 杆件结构
Framed stuctures
平面杆件结构 Plane structures: all the members and the applied loads lie in a single plane Otherwise the structures are spacial structure 空间 杆件结构
做题练习是学习结构力学的重要环节。不做一定 量的习题就很难对基本概念和方法有深入的理解和 掌握，也很难培养较好的计算能力。 Do exercises to solve some concrete problems is a key link in the study of the subject. If we don’t do a definite quantity of exercises it is difficult to understand the basic concepts and master the basic methods, and difficult to develop good ability to calculate.
II 计算能力Computing ability
(1)具有对各种结构确定计算步骤,进行计算的能力
determine the calculation procedure and calculate the structures。 (2)具有对计算结果进行定量校核或定性判断的能力the ability to verify the results quantitatively and judge the results qualitatively.
（2）讨论结构内力和变形的计算方法，进行 结构的强度和刚度的验算；Study the methods for analyzing internal forces and displacements to check the strength and stiffness of the structures; （3）讨论结构的稳定性以及在动力荷载作用 下的结构反应。Investigate the stability and the response to dynamic loadings.
双语课
Bilingual course
结构力学
Structural Mechanics
本学期教学内容 The content of the course in this semester
1.序论 Introduction 2.几何组成分析 Geometrical construction analysis 3.静定梁和静定刚架 Statically determinate beams and rigid frames 4.静定拱Statically determinate arches 5.静定平面桁架Statically determinate plane trusses 6.静定结构位移计算 Computation of displacements of structures 7.力法 Force method 11.影响线 Influence lines
Floors and roofs of buildings
实体结构
Massive structures
长、宽、厚三个尺度大小相仿
Length,width and thickness has the same order
水工结构中的重力坝
Gravitational damp in hydraulic enineering
(3)选择计算方法的能力the ability to select
computation methods：for this purpose it is necessary to understand the characteristics of different methods, and choose appropriate method to calculate the structures要了解结构力学中的各种计算方法的特点，具有 根据具体问题选择恰当的计算方法的能力。
理论力学和材料力学是结构力学的基础和前提。Theoretical and material mechanics are the basis and necessary prerequisite for structural mechanics. 结构力学的分析方法 study methods： 包含理论分析、实验研究和数值计算，本教程只进行理 论分析和数值计算。为此需要考虑以下三方面的条件： Include analytical methods, experimental methods and numerical methods, here we study only analytical and numerical methods. For this purpose the next three aspects must be considered （1）力系的平衡条件或运动条件force equilibrium conditions or kinematical conditions; （2）变形续条件deformation compatibility conditions; （3）物理条件（本构方程）Physical conditions or constitutive equations linking stresses and strains or forces and displacements.
本教程主要研究平面杆件结构 This course mainly focuses on plane structures 结构的要求The demands to structures ： 强度 strength 刚度 stiffness 稳定性 stability
结构力学的主要任务：The objectives of the course
课程要求：
1.掌握课程常用的英语词汇，以便在考试时能 够理解英文试卷内容； 2.能够用英语理解课程的基本概念； 3.提倡用英语做作业； 4.不旷课，注意考勤，课堂安静，认真听讲。 5.勤奋学习，淡化学习方法； 6.独立认真做作业，作业整洁，不抄袭，按时交。 6.平时成绩占20％，主要考察考勤、作业、期 中考试，每学期写一篇小论文。 7.答疑，周二、周三下午，地点1－120。
结构的分类Classification os structures:
特点Characteristics
由杆件组成，是结构力学的研究对象
分类名称
Classification
实例Examples 梁Beams, 拱arches , 刚架rigid frames ,桁 架trusses
房屋中的楼板和壳体屋盖
结构力学与理论力学、材料力学、弹塑性力学的关系：the relationship between theoretical mechanics, material mechanics and theory of elasticity
1.理论力学着重讨论物体机械运动的基本规律
Theoretical mechanics mainly studies the basic laws of mechanical motions;
研究外力和其他外界因素作用下结构的受力和 变形，结构的强度、刚度、稳定性和动力反应，以 及结构的几何组成规律。Study the stressing and
deformation of structures under the action of external loads and other external factors, study the strength, stiffness, stability and dynamic response of structures, the geometrical construction rules.
英 文 作业示范
小论文示范
研讨会照片
第一章 绪论 Chapter I Introduction
§1-1 结构力学的研究对象和任务 The objective and task of Structural Mechanics
结构：建筑物、构筑物,或者能承担荷载起骨架作用的部分称为结构。
Structure is referred to as buildings, constructions or parts of them which can carry loads applied on them and maintain stability.
杆件结构
Framed structures
Composed by beams – the main objective of structural mechanics
又称薄壁结构，几何特征是其厚度要比 长度和宽度小的多 Thin-walled
板壳结构
Shells and plates
structures, thickness is much less than length and width.
3.弹塑性力学采用最少的假定,用严格的数学分析的方法研究固
体的受力、变形与破坏。主要研究板、壳及实体结构。Theory of elasticity and plasticity uses the minimal assumptions and uses rigorous analytical methods to study the stress, deformation and fracture of solids, mainly studies shells, plates and massive solids.