Basics In Civil Engineering

Methods of Structural Design   There are many methods of design out of them following two are more popular: 1. Working Stress Method. 2. Limit State Method.   1. Working Stress Method: In this method, uncertainties such as correct estimation of load, possibility of occurrence of higher design load, material imperfection and geometrical imperfections in the structural members were taken into account in one single factor known as factor of safety. A particular section just reaching to yield stress at a maximum stressed fiber is considered to be a benchmark for estimating the capacity of the steel. Structural members are not allowed to stress more than allowable stress to ensure perfect elasticity. Different factors of safety were used to arrive allowable stresses for different types of stresses in structural members such as beam, column, tension member, base plate and fastners. Using estimated working/ service loads and their logical combinations the sections are designed using

 Difference Between Flexible Pavement and Rigid Pavement The term pavement means the surfacing layer only. It is defined as a structure having several layers bound together and placed at the top of the soil subgrade so that it provides a smooth surface for the vehicles. So the main objective behind construction of pavement is to provide a smooth surface for the vehicles. Pavements are divided into two types with respect to their structural behavior: 1. Flexible Pavements 2. Rigid Pavements Sr. No. Particular Flexible Pavement Rigid Pavement 01 Flexural strength Flexible pavements are those which on the whole have low or negligible flexural strength and are rather flexible in their structural action under the loads Rigid pavements are those which posses flexural strength or flexural rigidity. 02 Damage It has self healing properties as it deforms elastically

Slump test can be employed either in laboratory or at site of work for measuring consistency of concrete. This test is used conveniently as a control test and gives an indication of the uniformity of concrete from batch to batch. Repeated batches of the same mix, brought to the same slump, will have the same water content and water cement ratio, provided the weights of aggregate, cement and admixtures are uniform and aggregate grading is within acceptable limits. Additional  information on workability and quality of concrete can be obtained by observing the manner in which concrete slumps. Figure: Typical Mould for Slump Test If concrete slumps evenly it is called  true slump . If one half of the cone slides down, it is called  shear slump . In case of shear slump, the slump value is measured as the difference in height between the height of the mould and the average value of the subsidence. Shear slump also indicates that the concrete is non cohesive and shows the characteristic of se