Analysis of Structures
Analysis of Structures
Contents·Introduction（绪论）·Definition of a Truss（桁架）·SimpleTrusses（简单桁架）·Analysis of TrussesbytheMethodof Joints（由节点法分析桁架）·Zero-forceMembers（零力杆）·AnalysisofTrussesbytheMethodof Sections（由截面法分析桁架）·AnalysisofFrames（刚架分析）2
Contents • Introduction（绪论） • Definition of a Truss（桁架） • Simple Trusses（简单桁架） • Analysis of Trusses by the Method of Joints（由节点法分析桁架） • Zero-force Members（零力杆） • Analysis of Trusses by the Method of Sections（由截面法分析桁架） • Analysis of Frames（刚架分析） 2
LntroductionD: For the equilibrium of structures made of severalEconnected parts, the internal forces as well the externalforces are considered.: In the interaction between connected parts, Newton's 3rdLaw states that the forces of action and reactionbetween bodies in contact have the same magnitude,Esame line of action, and opposite sense.: Three categories of engineering structures are considered:a) Frames: contain at least one one multi-force member,i.e., member acted uponby 3 or more forces.b) Trusses: formed from two-force members, i.e.,straight members with end point connections)Machines:structures containingmovingpartsdesigned to transmit and modify forces.3
Introduction • For the equilibrium of structures made of several connected parts, the internal forces as well the external forces are considered. • In the interaction between connected parts, Newton’s 3rd Law states that the forces of action and reaction between bodies in contact have the same magnitude, same line of action, and opposite sense. • Three categories of engineering structures are considered: a) Frames: contain at least one one multi-force member, i.e., member acted upon by 3 or more forces. b) Trusses: formed from two-force members, i.e., straight members with end point connections c) Machines: structures containing moving parts designed to transmit and modify forces. 3
Definition of a Truss. A truss consists of straight members connected atjoints. No member is continuous through a joint.B: Most structures are made of several trusses joinedtogether to form a space framework. Each trusscarries those loads which act in its plane and maybe treated as a two-dimensional structure.万: Bolted or welded connections are assumed to bepinned together. Forces acting at the member endsreduce to a single force and no couple. Only two-force members are considered. When forces tend to pull the member apart, it is intension. When the forces tend to compress themember, it is in compression.4
Definition of a Truss • A truss consists of straight members connected at joints. No member is continuous through a joint. • Bolted or welded connections are assumed to be pinned together. Forces acting at the member ends reduce to a single force and no couple. Only twoforce members are considered. • Most structures are made of several trusses joined together to form a space framework. Each truss carries those loads which act in its plane and may be treated as a two-dimensional structure. • When forces tend to pull the member apart, it is in tension. When the forces tend to compress the member, it is in compression. 4
Simple Trusses. Arigid truss will not collapse underthe application of a load.DA.Asimpletrussis constructedbysuccessively adding two members andone connection to the basic triangularDBtruss. In a simple truss, m =2n -3 wherem isthetotal number of membersand n is the number of jointsBEDF5
Simple Trusses • A rigid truss will not collapse under the application of a load. • A simple truss is constructed by successively adding two members and one connection to the basic triangular truss. • In a simple truss, m = 2n - 3 where m is the total number of members and n is the number of joints. 5