Flat Plate The flat plate is a two-way reinforced concrete framing system utilizing a slab of uniform thickness, the simplest of structural shapes. Flat Plate System Introduction A flat plate is a one- or two-way system usually supported directly on columns or load bearing walls. It is one of the most common forms of construction … Read more
What is Punching Shear? Punching shear is a type of failure of reinforced concrete slabs subjected to high localized forces. In flat slab structures this occurs at column support points. The failure is due to shear. This type of failure is catastrophic because no visible signs are shown prior to failure. Punching shear failure disasters … Read more
Spalling of Concrete – Causes, Prevention & Repair ingress of moisture of air into concrete causes corrosion of reinforcement and results in the volume expansion of steel bars, consequently causing cracks & spalling of concrete cover The word Spall in engineering, describes the chips or fragments of a material that is broken off a bigger … Read more
Diagonal Cracks in Foundation and Walls Diagonal cracking is an inclined crack beginning at the tension surface of a concrete member. Steep diagonal cracks appear in concrete foundation due to point loads that exceed the compressive strength of the concrete. This type of failure, known as settlement, can happen due to “volume changes in clay soils … Read more
Ductile Fracture of Metals by Necking – Cup and Cone Failure extensive plastic deformation and energy absorption (“toughness”) before fracture Fracture: separation of a body into pieces due to stress, at temperatures below the melting point. Steps in fracture: crack formation crack propagation Major Fracture Mechanisms Depending on the ability of material to undergo plastic … Read more
Concrete Creep Definition, Creep deformation Stages & Design Strategies When load is applied on a concrete specimen, shows an instantaneous deformation followed by slow increase of deformation is called concrete creep. Creep is a time-dependent permanent (plastic) deformation under a certain applied load. Generally, creep occurs at high temperature (thermal creep) but can also happen … Read more
Buckling of Columns – Euler Theory for Elastic Buckling BUCKLING – Loss of stability –Axial loads cause lateral deformations (bending-like deformations) Buckling of Columns is a form of deformation as a result of axial- compression forces. This leads to bending of the column, due to the instability of the column. This mode of failure is … Read more
Freeze Thaw Damage of Concrete – Effects & Preventive Measures “damage to concrete caused by extreme temperature variations as noted by random pattern cracking.” A severe exposure condition on portland cement concrete structures is exposure to cycles of freezing and thawing. Air entrainment is used to enhance the freeze-thaw resistance of portland cement concrete exposed … Read more
Significance of Delayed Ettringite Formation and Damage Mechanisms Ettringite is formed in hydrated Portland cement system as a result of the reaction of calcium aluminate with calcium sulfate, both present in Portland cement. In the cement system, the presence of ettringite depends on the ratio of calcium sulfate to tri-calcium aluminate (C3A); when this ratio … Read more