Intro to Structural Midterm 1

Structure

Structure

An assembly of structured elements/members that serves a purpose

Different Types of Shape

Line Forming Elements

Surface Forming Elements

Different Types of Physical Behavior

Rigid

Flexible (Nonrigid)

Line Elements

Straight Line or Curved

Surface Elements

Planar

Curved (Single or Double Curvature)

Rigid Structure

The surface is stiff and does not undergo appreciable changes in shape with changes in the loading condition

Nonrigid Structure

The shape of the structure changes with changes in the loading condition

Creation of Structural System

1. Start with basic elements

2. Assemblies of basic elements from primary structural units

3. Continue with bringing together primary structural units that result in aggregations

Beams and Columns

Horizontal elements that pick up loads that are applied transversely to their lengths and transfer the loads to the supporting vertical columns or posts. Columns are loaded axially by the beams and transfer loads to the ground.

Frames

Has structural action due to the rigid joints between its vertical and horizontal memebers

Trusses

Structural members made by assembling short, straight members into triangulated patterns

Arches

Curved, line-forming structural members that spans two points

Walls and Plates

Rigid, surface-forming structures. Long, narrow, rigid plates can be joined along the edges and used to span horizontally. These are called folded plated.

Cylindrical Shells and Vaults

Singly curved plate structures

Spherical Shells and Domes

Doubly curved structures

Cables

Flexible structural elements, think suspension cables!

Membranes, Tents, and Nets

A thin flexible sheet. Nets are 3-dimensional surfaces made up of crossed and curved cables

Post and Beam

Simple Truss

Frame

Trussed Frame

Load-Bearing Walls

Plate or Slab

Block Dome

Rigid Shell

Block Arch

Three-Hinged Arch

Rigid Fixed Arch

Two-Hinged Arch

Arch with tie-rod

Arch with Buttresses

Folded Plate

Geodesic Dome

Cylindrical Shell$

Ribbed Dome

Block Vault

Hyperbolic Paraboloid

Suspended Cable

Double Cable

Suspended Cables

Pneumatic Membrane

Cable-Sytayed

Tent

Stretched Net/Cable Net

One-Level System

No floor beams, just two wood-bearing walls and a plate

Two-Level System

Two load-bearing walls or columns, floor beams, and a plate

Three-Level System

Columns and two levels or beams and a plate

Plate Bending: One-Way Structures

Plate Bending: Two-Way Structure

Load Path

How the loads applied on a flat plate are transferred throughout the whole structural system

Types of Failures: Wind or Earthquake Forces

Overturning, Sliding, Lateral Racking,

Types of Failures: Gravity Loads

Twisting, Member Failures

Preventing Overturning or sliding

Wide, heavy footings and Piles

Preventing Lateral Racking or twisting

Preventing Member Failures

How do Compression Members fail (Both short and long)?

Short: Crushing

Long: Buckling at low levels

How do tension members fail?

By pulling apart

Torsion

Twisting Action

Bearing

Stresses cause localized crushing

Deflections

Can be excessive

Efficiency

Measured by the amount of material required to support a given load in space under the conditions and constraints specified

Construction

Measured by the amount of effort or human power required to construct structure, the type of equipment used, and the total amount of time it takes to complete construction

Costs

Measured by the amount and cost of material used