Arches And Force Transferring Mechanism -: CREATED BY :-

ALAY MEHTA 141080106011SHIVANI PATEL 141080106021KAVIN RAVAL 141080106026KUNTAL SONI 141080106028

SUBMITED TO :-Prof. ROCKY PATEL

Arch• An arch is a curved structure that spans a space and may or may

not support weight above it. Arch may be synonymous with vault, but a vault may be distinguished as a continuous arch forming a roof.

• An arch is a pure compression form. 

• It can span a large area by resolving forces into compressive stresses and, in turn eliminating tensile stresses.

• This is sometimes referred to as arch action.

Arch• As the forces in the arch are carried to the ground, the

arch will push outward at the base, called thrust.

• As the rise, or height of the arch decreases, the outward thrust increases.

• In order to maintain arch action and prevent the arch from collapsing, the thrust needs to be restrained, either with internal ties or external bracing, such as abutments.

Types Of Arches

Triangular arch Round arch or Semi-circular

arch

Segmental arch

Unequal round arch

Lancet arch Equilateral pointed arch

Shouldered flat arch

Types Of Arches

Trefoil arch Horseshoe arch Three-centered

arch

Elliptical arch Inflexed arch

Ogee archReverse

ogee arch Tudor arch Parabolic arch

Forces• Instead of pushing straight down,

the load of an arch bridge is carried outward along the curve of the arch to the supports at each end.

• The weight is transferred to the supports at either end.

• These supports, called abutments, carry the load and keep the ends of the bridge from spreading out.

Forces• The load at the top of the key

stone makes each stone on the arch of the bridge press on the one next to it.

• This happens until the push is applied to the end supports or abutments, which are embedded in the ground. 

• The design of the arch, the semicircle, naturally diverts the weight from the bridge deck to the abutments.

Forces• The ground around the

abutments is squeezed and pushes back on the abutments.

• For every action there is an equal and opposite reaction. The ground which pushes back on the abutments creates a resistance which is passed from stone to stone, until it is eventually pushing on the key stone which is supporting the load

Forces• Compression

Arch bridges are always under compression.

• The force of compression is pushed outward along the curve of the arch toward the abutments.

• TensionThe tension in an arch is negligible.

• The natural curve of the arch and its ability to dissipate the force outward greatly reduces the effects of tension on the underside of the arch.

• The greater the degree of curvature , the greater the effects of tension on the underside

Arches• Dissipation

As we just mentioned, the shape of the arch itself is all that is needed to effectively dissipate the weight from the center of the deck to the abutments.

• As with the beam bridge, the limits of size will eventually overtake the natural strength of the arch

• Arch types are few -- . The only real subcategories come in the form of cosmetic design. There are, for example, Roman, Baroque and Renaissance arches, all of which are architecturally different but structurally the same .

• Arches are fascinating in that they are a truly natural form of bridge. 

Arches• It is the shape of the structure that gives it its strength. 

• An arch bridge doesn't need additional supports or cables.

• In fact, an arch made of stone doesn't even need mortar. 

• Ancient Romans built arch bridges (and aqueducts) that are still standing, and structurally sound, today.

• These bridges and aqueducts are real testaments to the natural effectiveness of an arch as a bridge structure.