Static and Strength of MaterialsChapter 4-Structures-Part I

Mehdi Tale Masouleh

November 8, 2013

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresIntroductions

In this chapter we focus on thedetermination of the forces internal toa structures.That is, forces of action and reactionbetween the connected members.Thus, the third law of Newton wouldbe of great help!A definition by Meriam: Anengineering structure is any connectedsystem of members built to support ortransfer forces and to safely withstandthe loads applied to it.

There are four categories ofengineering structures:

1 Trusses2 Frames3 Machines4 Beams

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresIntroductions

In this chapter we focus on thedetermination of the forces internal toa structures.That is, forces of action and reactionbetween the connected members.Thus, the third law of Newton wouldbe of great help!A definition by Meriam: Anengineering structure is any connectedsystem of members built to support ortransfer forces and to safely withstandthe loads applied to it.

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresIntroductions

In this chapter we focus on thedetermination of the forces internal toa structures.That is, forces of action and reactionbetween the connected members.Thus, the third law of Newton wouldbe of great help!A definition by Meriam: Anengineering structure is any connectedsystem of members built to support ortransfer forces and to safely withstandthe loads applied to it.

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresIntroductions

In this chapter we focus on thedetermination of the forces internal toa structures.That is, forces of action and reactionbetween the connected members.Thus, the third law of Newton wouldbe of great help!A definition by Meriam: Anengineering structure is any connectedsystem of members built to support ortransfer forces and to safely withstandthe loads applied to it.

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresIntroductions

In this chapter we focus on thedetermination of the forces internal toa structures.That is, forces of action and reactionbetween the connected members.Thus, the third law of Newton wouldbe of great help!A definition by Meriam: Anengineering structure is any connectedsystem of members built to support ortransfer forces and to safely withstandthe loads applied to it.

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresIntroductions

In this chapter we focus on thedetermination of the forces internal toa structures.That is, forces of action and reactionbetween the connected members.Thus, the third law of Newton wouldbe of great help!A definition by Meriam: Anengineering structure is any connectedsystem of members built to support ortransfer forces and to safely withstandthe loads applied to it.

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresEngineering Structures

Truss: are designed tosupport loads and are usuallystationary, fully constrainedstructures.Trusses consist exclusively ofstraight members connectedat joints located at the endsof each member.Members of a truss,therefore, are two forcesmembers, i.e., membersacted upon by two equal andopposite forces directedalong the member.

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresEngineering Structures

Truss: are designed tosupport loads and are usuallystationary, fully constrainedstructures.Trusses consist exclusively ofstraight members connectedat joints located at the endsof each member.Members of a truss,therefore, are two forcesmembers, i.e., membersacted upon by two equal andopposite forces directedalong the member.

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresEngineering Structures

Truss: are designed tosupport loads and are usuallystationary, fully constrainedstructures.Trusses consist exclusively ofstraight members connectedat joints located at the endsof each member.Members of a truss,therefore, are two forcesmembers, i.e., membersacted upon by two equal andopposite forces directedalong the member.

I dedicate this photo to the Eng.Power of the class

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresEngineering Structures

Truss: are designed tosupport loads and are usuallystationary, fully constrainedstructures.Trusses consist exclusively ofstraight members connectedat joints located at the endsof each member.Members of a truss,therefore, are two forcesmembers, i.e., membersacted upon by two equal andopposite forces directedalong the member.

This is your day so enjoy! Onemore!

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresEngineering Structures

Truss: are designed tosupport loads and are usuallystationary, fully constrainedstructures.Trusses consist exclusively ofstraight members connectedat joints located at the endsof each member.Members of a truss,therefore, are two forcesmembers, i.e., membersacted upon by two equal andopposite forces directedalong the member.

Hey! Power Eng. You depend onMechanical Eng. ;)

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresEngineering Structures

Truss: are designed tosupport loads and are usuallystationary, fully constrainedstructures.Trusses consist exclusively ofstraight members connectedat joints located at the endsof each member.Members of a truss,therefore, are two forcesmembers, i.e., membersacted upon by two equal andopposite forces directedalong the member.

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresEngineering Structures

Truss: are designed tosupport loads and are usuallystationary, fully constrainedstructures.Trusses consist exclusively ofstraight members connectedat joints located at the endsof each member.Members of a truss,therefore, are two forcesmembers, i.e., membersacted upon by two equal andopposite forces directedalong the member.

Truss in robotic contexts

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresEngineering Structures

Truss: are designed tosupport loads and are usuallystationary, fully constrainedstructures.Trusses consist exclusively ofstraight members connectedat joints located at the endsof each member.Members of a truss,therefore, are two forcesmembers, i.e., membersacted upon by two equal andopposite forces directedalong the member.

Truss in robotic contexts

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

StructuresEngineering Structures

Truss: are designed tosupport loads and are usuallystationary, fully constrainedstructures.Trusses consist exclusively ofstraight members connectedat joints located at the endsof each member.Members of a truss,therefore, are two forcesmembers, i.e., membersacted upon by two equal andopposite forces directedalong the member.

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

Plane TrussesSimple Trusses

A plane trussA simple truss is a planartruss which begins with atriangular element and canbe expanded by adding twomembers and a joint. Forthese trusses, the number ofmembers (m) and thenumber of joints (j) arerelated by the equation:

m = 2j − 3

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

Plane TrussesSimple Trusses

A plane trussA simple truss is a planartruss which begins with atriangular element and canbe expanded by adding twomembers and a joint. Forthese trusses, the number ofmembers (m) and thenumber of joints (j) arerelated by the equation:

m = 2j − 3

A simple truss

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

Plane TrussesSimple Trusses

A plane trussA simple truss is a planartruss which begins with atriangular element and canbe expanded by adding twomembers and a joint. Forthese trusses, the number ofmembers (m) and thenumber of joints (j) arerelated by the equation:

m = 2j − 3

non-simple truss

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

Plane TrussesSimple Trusses

A plane trussA simple truss is a planartruss which begins with atriangular element and canbe expanded by adding twomembers and a joint. Forthese trusses, the number ofmembers (m) and thenumber of joints (j) arerelated by the equation:

m = 2j − 3

non-simple truss

Statics and Strength of Materials-Tale Masouleh-Part INovember 8, 2013

Plane TrussesAnalysis and design assumptions

The force analysis of a trussis based on the followingassumptions:

1 All load are applied at thejoints

2 The weight of the trussmember is often neglectedas the weight is usuallysmall a compared to theforces supported busmooth pins.

3 The above is satisfied inmost practical caseswhere the joint are formedby bolting or welding

These leads to have:

Thus, the members act astwo-force members. They areloaded in either tension orcompression. Often compressivemembers are made thicker toprevent buckling.