STRUCTURAL ANALYSIS

structural analysis

it is the prediction of the performance of a given structure under prescribed loads and/ or other external aspects, such as support movements and temperature changes

tension structures

structures that are subjected to pure tension under the action of external loads

compression structures

structures that develop mainly compressive stresses under the action of external loads

truss structure

it is composed of straight members connected at their ends by hinged connections to form a stable configuration

shear structures

structures such as reinforced concrete shear walls that are used in multistory buildings to reduce lateral movements due to wind loads and earthquake excitations

bending structures

structures that develop mainly bending stresses under the action of external loads

bending

some of the most commonly used structures, such as beams, rigid frames, slabs, and plates, can be classified as ______________ structures

beam

it is a straight member that us loaded perpendicular to its longitudinal axis

dead loads

gravity loads of constant magnitudes and fixed positions due to the weight of the structural system itself and any other material permanently attached to it

live loads

gravity loads of varying magnitudes and/or positions cause by the use of the structure, these may include weights of objects temporarily placed on a structure, moving vehicles, or natural forces

impact

When live loads are applied rapidly to a structure, they cause larger stresses than those that would be produced if the same loads would have been applied gradually. The dynamic effect of the load that causes this increase in stress in the structure is referred to as _____________

wind loads

lateral loads produced by the flow of wind around the structure

earthquake loads

load that produced loadings on a structure through its interaction with the ground and its response characteristics

snow loads

loads due to snow which are considered in other countries that can cause a possible failure of the structure

hydrostatic loads

loads on structure used to retain water such as dams and tanks as well as coastal structures designed to resist hydrostatic pressure

soil loads

loads from soil pressure resisted by retaining walls, underground structures, and basement walls and floors

thermal loads

loads on a structure caused by stresses due to temperature changes, shrinkage of materials, fabrication errors, and differential settlements of supports

equilibrium

a structure is considered to be in __________ if, initially at rest, it remains at rest when subjected to a system of forces and couples

external forces

actions of other bodies on the structure under consideration

applied forces

reaction forces or reactions

classification of external forces

applied forces

it is usually referred to as loads, and have a tendency to move the structure and are usually known in the analysis

internal forces

forces and couples exerted on a member or portion of the structure by the rest of the structure

internal forces

these forces develop within the structure and hold various portions of it together

internal forces

these forces always occur in equal but opposite pairs, because each member or portion exerts back on the rest of the structure the same forces acting upon it but in opposite directions

supports

it is used to attach structures to the ground bodies, thereby restricting their movements under the action of applied loads

internally stable or rigid

a structure is considered to be __________, if it maintains its shape and remains a rigid body when detach from the supports

internally unstable or non rigid

a structure is considered ____________ if it cannot maintain its shape and may undergo large displacements under small disturbances when not supported externally

rigid structure

it implies that the structure offers significant resistance to its change of shape

nonrigid structure

it offers negligible resistance to its change of shape when detached from support and would open collapse under its own weight when not supported externally

externally statically determinate structures

structures with support reactions that can be determined by solving the equations of the equilibrium

externally statically indeterminate structures

structures that are supported by more than three reactions and these reactions cannot be determined by the three equation of equilibrium

externally statically unstable structures

structures that are supported by fewer than three support reactions and the reactions are not sufficient to prevent all possible movements of the structure in its plane

statically determinate

r = 3n

statically indeterminate

r > 3n

unstable

r < 3n

degree of indeterminate

r - 3n

statically determinate

b + r = 2j

statically indeterminate

b + r > 2j

unstable

b + r < 2j

steel cables

an efficient method for supporting loads over long spans is by the use of ____________, such as for suspension bridges, cable car systems, and similar structures

parabola

a cable supporting a load which is uniform along the horizontal will take the shape of a ___________

catenary

a cable supporting only its uniform weight, such as an electric transmission line, will form a _______

arched

it is used for buildings where large clear spans are required, such as for gymnasiums, hangars, churches, warehouses, and convention halls

trusses

it is an assemblage of straight members connected at their ends by flexible connections to form a rigid configuration

method of joints

in this method, the axial forces in the members of a statically determinate truss are determined by considering the equilibrium of its joints

method of sections

this method involves cutting the truss into two portions by passing an imaginary section through the members whose forces are desired