truss & frame-10.01.03.097

Welcome to My Presentation on

Truss & Frame

PRESENTED BY……

Md. Sadik Hasan 10.01.03.097Sec: B

Trusss

A truss is a structure composed of slender members joined together at their end points. Planar trusses lie in a single plane. Typically, the joint connections are formed by

bolting or welding the end members together to a common plate, called a gusset plate.

Definition of truss

Common Types of Trusses

Roof trussesPratt TrussesHowe TrussesWarren TrussesBridge trussesCoplanar Trusses

Roof trusses

Roof trusses, which are structural components of houses or commercial buildings, support the weight of roof timbers and coverings. Usually, they are constructed from pieces of timber or steel which are nailed, bolted, or pegged together to form a mutually supporting and strong base for a roof.

Roof trusses -in general, the roof load is transmitted to the truss by a series of purling. The roof truss along with its supporting columns is termed a bent. The space between bents is called a bay.

Definition of roof trusses:

Roof trusses

Bridge trusses

Definition of Bridge trusses

Bridge trusses - the load is transmitted by the deck to series of stringers and then to a set of floor beam.

The floor beams are supported by two parallel trusses.

The supporting trusses are connected top and bottom by lateral bracing.

Additional stability may be provided by portal and sway bracing.

Common Bridge Truss

Common Bridge Truss

Coplanar Trusses

Simple truss Compound truss

Complex truss

Method of Sections:If the forces in only a few members of a truss are to be determined, the method of sections is generally the most appropriate analysis procedure.

The method of sections consists of passing an imaginary line through the truss, cutting it into sections.

Each imaginary section must be in equilibrium if the entire truss is in equilibrium.

∑Fx = 0 ∑Fy = 0 ∑Mz = 0

Imagine cutting a structure into two sections about line 11

Left side Right side

Typically the section with the fewest forces or with section with the most convenient geometry is selected:

Apply the three equations ofequilibrium to the section.

If possible, attempt to developan equation in just oneunknown.

Look for points where the linesof action of several forces areconcurrent.

Frame

Defination of frame A frame is a structural system that supports other components of a

physical construction.

A-Frame a basic structure designed to bear a load in a light weight economical manner.

Frame structures are the structures having the combination of beam, column and slab to resist the lateral and gravity loads. These structures are usually used to overcome the large moments developing due to the applied loading.

Types of frame structures

Rigid frame structure Pin ended Fixed ended

Braced frame structure Gabled frames Portal frames

Pin Ended Rigid Structural Frames

A pinned ended rigid frame system usually has pins as their support conditions. This frame system is considered to be non rigid if its support conditions are removed

Fix Ended Rigid Frame Structure

In this type of rigid frame systems end conditions are usually fixed.

Rigid frame structure

Braced Structural Frames

Gabeled Structural Frame: Gabled frame structures usually have the peak at their top. These

frames systems are in use where there are possibilities of heavy rain and snow .

Portal Structural Frame A continuous rigid frame with a restrained joint between the column

and beam.

Difference Between Trusses and Frames

Trusses: Members are subjected totension/compression only.

Composed of rods

Usually more simple to calculate, more weight effective.

Frames:

At least one member is subjected to bending, shear or torsion.

Composed of bars

Usually more simple to manufacture, and to place in tight layout.

Trusses: Joints are considered as having frictionless pins in trusses with no moments at the member ends.

The forces in trusses are only axial. Due to this members are equally stressed throughout their cross-section.

The design of a member in case of a truss is economical.

Frames:

In rigid frames,the members are rigidly connected having appreciable moments at the member ends.

Due to bending moments, the fibers away from the neutral axis have maximum stresses and fibers close to the neutral axis have less stress.The design of rigid frame member is less economical as compared to trusses.

The End