It is convenient to think of a building as consisting of three major parts: the superstructure, which is the above-ground portion of the building; the substructure, which is the habitable below-ground portion; and the foundations, which are the components of the building that transfer its loads into the soil (Figure 1). There are two basic […]
An earthquake is a sudden, rapid shaking of the earth surface caused by the breaking and shifting of rocks beneath. During earthquake, ground motion occurs in a random fashion in all directions radiating from a point within earth crust, called epicentre. It causes vibrations of structures and induces inertia forces on them. As a result
Where building substructures enclose basements, parking garages, or other usable space, groundwater must be kept out. Concrete alone is rarely adequate for this purpose. Moisture can migrate through its microscopic pores, or through other pathways created by shrinkage cracks, form tie holes, utility penetrations, and the joints between concrete pours. To ensure a substructure’s resistance
Fire Resistant Buildings It is reported that in USA fire kills more people each year than all other natural disasters combined including floors, cyclones and earthquake. The fire load in a building should be kept to the minimum possible. The term fire load indicates the amount of heat liberated in kilo joules per square metre
Mechanical Properties of Materials The mechanical behavior of materials is the response of the material to external loads. All materials deform in response to loads; however, the specific response of a material depends on its properties, the magnitude and type of load, and the geometry of the element. Whether the material “fails” under the load
Viscoelastic Behavior of Materials The previous discussion assumed that the strain was an immediate response to stress. This is an assumption for elastic and elastoplastic materials. However, no material has this property under all conditions. In some cases, materials exhibit both viscous and elastic responses, which are known as viscoelastic. Typical viscoelastic materials used in
Variability of Materials It is essential to understand that engineering materials are inherently variable. For example, steel properties vary depending on chemical composition and method of manufacture. Concrete properties change depending on type and amount of cement, type of aggregate, air content, slump, method of curing, etc. The properties of asphalt concrete vary depending on
Phase Diagrams of Alloys To produce alloy metals, the components are heated to a molten state, mixed, and then cooled. The temperature at which the material transitions between a liquid and a solid is a function of the percentages of the components. The liquid and solid states of a material are called phases, and a
Iron Carbon Phase Diagram In refining steel from iron ore, the quantity of carbon used must be carefully controlled in order for the steel to have the desired properties. The reason for the strong relationship between steel properties and carbon content can be understood by examining the iron–carbon phase diagram. Figure 1 shows a commonly
Heat Treatment of Steel Properties of steel can be altered by applying a variety of heat treatments. For example, steel can be hardened or softened by using heat treatment; the response of steel to heat treatment depends upon its alloy composition. Common heat treatments employed for steel include annealing, normalizing, hardening, and tempering. The basic