Designer This is a guest post by Philip White
Concrete has been used for many years for providing a permanent or temporary barrier, or blockade in a variety of situations. One of the most common applications is for concrete barriers on the highway either in the centre of the road to divide opposite lanes of motorways, or for traffic diversion and channelling during work on the highways.
Here are a few simple steps that are to be followed for the design of Rolled Steel Beam:
Calculate the maximum Bending Moment and Shear Force
Depending upon whether the beam is laterally restrained or unrestrained, calculate the permissible stress in bending compression (sigma bc) using the equation;
sigma bc = 0.66fy
Find the required Section Modulus (Zreq)
Zreq = M/sigma bc
From the structural tables, choose a suitable section such that the section modulus is slightly more than the required section modulus.
Check for shear.
Calculate the maximum Shear force in the beam. Calculate the average shear stress in the web and this should be less than 0.4fy.
Tv = (Shear Force)/HLw
where = H = height of the web
Lw = length of the web
Check for deflection
Ymax < 1/325 of span
A reinforced cement concrete beam 300mm wide and 500mm effective depth is subjected to a shear force of 40KN at the ends. The beam is provided with 6 bars of 20mm diameter of which 3 bars are cranked at 45 degrees. Design the shear reinforcement for M20 grade concrete.
Here are the steps for the design of Shear Reinforcement in a beam:
Width of the beam = b = 300mm
Shear force = Vu = 40KN
Effective depth = d = 500mm
Area of steel, Ast = 3 x 3.14/4 x 20 x 20 = 942.47 mm2
Nominal shear stress
Tv = Vu/bd
Tv = 40 x 1000/(300 x 500) = 0.26N/mm2
The beam is failed by the diagonal tension in which the cracks start from support and extend upto a distance equal to effective depth and making an angle more or less than 45 degrees.
Nominal shear stress
Tv = Vu/bd
Where, Vu = shear force due to design load
b = width of the beam
d = depth of the beam
Percentage of steel
Percent steel = Ast/bd x 100
The design of the components of the RCC structure can be done in the following two ways:
Design of Simply Supported Slabs
In this article, we are going to discuss the major difference between the two important methods of RCC design. This will help us understand the mechanics of the Structural Design and which method is to be adopted for better efficiency.
To make the roads functional and provide smooth flow of traffic without creating much chaos; important elements are to be incorporated in road design.
In the previous article, we discussed “Different types of roads based on different purposes” and the “Important design factors the influence the construction of roads”. Elements of Road Design is the second step towards understanding the concept of Road Design.
We will also discuss “Types of Road Junctions” and “Parking Methods” in my successive articles.
The general term in which we describe the means of Vehicular Access in one word is “Roads.” In this article, we are going to discuss in detail different types of roads for different purposes. We will also deal with the design factors that are to be considered while designing roads and Road Junctions.
Here are the names of different types of roads for different types of vehicles and which depend on its width and purpose of construction:
Specimens used – Cube, cylinders and prisms.
Prevention of failure of Concrete will help preventing the building from failure. Good quality concreting strengthens the building and keeps it standing. Failure of Concrete results in structural failure of the building. Therefore, to prevent this from happening, measures have to be taken in order to strengthen the building and prevent it from structural failure.
It does not affect the strength adversely and reduces scatter compared with uncapped specimens.
Tests are held at 28 days, 7 days and 3 days. Constituent of mix should be such that concrete can be transported, placed and finished easily without segregation.
Optimum water varies for different methods of compaction
If we add more water, the workability may increase may increase but core has more voids
The voids result due to –
The entrapped air voids are caused by grading of fine aggregate.
Excess water evaporating later excess – (water) voids are due to increase in workability
Aim should be to have maximum density – therefore for maximum compaction, you will have to have optimum water cement ratio, at which both the type voids are at minimum.