Sage-Tips

What are the effects of earthquake on reinforced concrete structures?

Thus, under strong earthquake shaking, the beam ends can develop tension on either of the top and bottom faces. Since concrete cannot carry this tension, steel bars are required on both faces of beams to resist reversals of bending moment. Similarly, steel bars are required on all faces of columns too.

What are the effects of corrosion in concrete?

Steel corrosion in reinforced concrete structures produces loss of reinforcement area and damage in the surrounding concrete. As a consequence, increases in deflections, crack widths and stresses may take place, as well as a reduction of the bearing capacity, which depends on the structural scheme and redundancy.

Under what structural force is concrete weak and fails by cracking?

Concrete, although strong in compression, is weak in tension. For this reason it needs help in resisting tensile stresses caused by bending forces from applied loads which would result in cracking and ultimately failure.

How does steel reinforcement overcome the weakness of concrete in tension?

Reinforcement within concrete creates a composite material, with the concrete providing strength against compressive stress while the reinforcement provides strength against tensile stress. I made a new beam with a couple of steel threaded rods cast into the lower part of the concrete.

What happens to building during earthquake?

Inertia Forces in Structures When an earthquake causes ground shaking, the base of the building would move but the roof would be at rest. The inertia forces can cause shearing of the structure which can concentrate stresses on the weak walls or joints in the structure resulting in failure or perhaps total collapse.

How do earthquakes affect buildings structures?

The shaking from an earthquake can turn loose soil into a liquid during an earthquake. Liquefaction can undermine the foundations and supports of buildings, bridges, pipelines, and roads, causing them to sink into the ground, collapse or dissolve.

What is concrete corrosion?

Concrete corrosion is the chemical, colloidal or physicochemical deterioration and disintegration of solid concrete components and structures, due to attack by reactive liquids and gases. This type of corrosion causes widespread damage to critical sewage pipelines, bridges and other critical assets made of concrete.

What causes concrete corrosion?

Causes: Chloride intrusion, oxygen-water exposure, corrosive chemical environment surrounding reinforcing steel, drop in alkalinity, improper placement or concrete coverage of steel reinforcement (rebar).

What causes cracking in concrete?

A piece of concrete in the open air usually shrinks during hardening. This shrinkage is due to the evaporation of part of the water contained in the concrete. Cracking occurs when shrinkage forces become greater than the strength of the concrete.

Which conditions the cracking occurs in concrete?

While cracks may develop in concrete for a variety of causes, the underlying principle is the relatively low tensile strength of concrete. Visible cracking occurs when the tensile stresses exceed the tensile strength of the material.

How is concrete weak in tension?

Concrete is weak in tension because of the presence of an internal weak link between concrete components known as the Interfacial Transition Zone or ITZ. Because of concrete’s limitation in tensile stresses, steel reinforcements are done in concrete structures.

How does steel strengthen concrete?

reinforced concrete, concrete in which steel is embedded in such a manner that the two materials act together in resisting forces. The reinforcing steel—rods, bars, or mesh—absorbs the tensile, shear, and sometimes the compressive stresses in a concrete structure.

Why is tension stiffening required in the concrete damaged plasticity model?

This behavior also allows for the effects of the reinforcement interaction with concrete to be simulated in a simple manner. Tension stiffening is required in the concrete damaged plasticity model.

What are the advantages and disadvantages of reinforced concrete construction?

Reinforced concrete has some characteristics that enhance its ability to resist earthquake forces, and others that are detrimental. Perhaps the greatest advantage of reinforced concrete construction is continuity. If one component fails, the load is transferred to other components and the structure stands.

How do you model the postfailure behavior of cracked concrete?

The postfailure behavior for direct straining is modeled with tension stiffening, which allows you to define the strain-softening behavior for cracked concrete. This behavior also allows for the effects of the reinforcement interaction with concrete to be simulated in a simple manner.

What is the model of failure of concrete?

The model is a continuum, plasticity-based, damage model for concrete. It assumes that the main two failure mechanisms are tensile cracking and compressive crushing of the concrete material. The evolution of the yield (or failure) surface is controlled by two hardening variables, ˜εp