a)
AIM :
To create a model of g+7 building given in the arhitectural drawing as per the provisions of IS 1893 and IS 13920 followed by response spectrum analysis.
PROCEDURE:
plan is plotted according to the dimensions given in the architectural plan using grids and storeys.
now the material properties are added such as grade of concrete, rebars and shear reinforcement.
after this the section properties are added such as size of columns ,beams ,slabs and shear walls.
columns and beams along with shear walls are placed in the plan as shown in figure and pier labels are assigned.
brickwall load is apllied to all the beams of 3.6kn/m.
now live load is assigned to the slabs as per the provisons of IS 875 and reduction factor is assigned.
live load on the roof is applied less compared to other storeys.
now different load combintions are assigned followd by mass source and diaphragm.
now it is checked for response spectrum analysis.
deformed shape of the model is obtained.
values for the base reations are obtained.
story response plot is analysed as we can see that the drift is within the permissible limit i.e 4% in both
x and y direction.
now base reactions due to shear wall is obtained in x and y direction.
b)
After establishing the proposed project, the next thing to consider is to determine the appropriate design load combinations. Generally, load combination is composed of individual loads, i.e. dead load superimposed dead loads and live loads that are combined together to come up for a strength design and allowable stress design. By the ASCE7-10 (section 1.2.1) code definition, strength design is the product of the nominal strength and a resistance factor while the allowable stress design is composed of computed forces produced in the member by factored loads that shall not exceed the member design strength.
Each design code and standards had a different recommendation when it comes to loading combinations. In this article, we will emphasize the design load combinations as recommended by ASCE7-10 for basic design load combinations with the touch of UBC97 seismic load combinations. Let us bear in mind that the use of design load and load combinations is depending on the approved code and standards authorize by your local authority having jurisdiction.
Before we proceed into the lists of load combinations, let us take a look at the following symbols used:
- Ak= load or load effect arising from extraordinary event A
- D= dead load
- Dt= weight of ice
- E= Earthquake Load
- H= lateral earth pressure load
- L= live load
- Lr= roof live load
- R= rain load
- S= Snow load
- T=self-straining load
- W= wind load
- Wi= wind on ice
LOAD COMBINATIONS according to ASCE7-10
According to ASCE7-10 section 2.3.2, buildings and other structures, components, and foundation shall be designed so that their design strength equals or exceeds the effects of the factored loads in the following combinations.
c)
- Composites allow the construction of structures of almost limitless shapes. They can be molded into very complicated shapes that other materials would struggle to form.
- Composites are strong, lightweight and have a great strength to weight ratio.
- They have natural corrosion resistance, are non-conductive, non-magnetic and are radar transparent.
- Composites can have low thermal conductivity.
Composites are used in a wide variety of industries. From sporting goods to aircraft, composites can be the optimum choice for your project. We can show you how to best utilize composites in your design for creating models that get you faster to the manufacturable end product with still having high impact strength. Composites don’t yield, they are not brittle and they routinely perform in severe environments. Composites can be the material of choice for a vast array of projects and applications.
d)
Composite beams are typically hot rolled steel sections that act compositely with a concrete slab. Shear studs are required to transfer force between the steel section and the concrete slab. The studs are welded to the beam, normally through the deck sheet. This enables the concrete slab to act like a large top flange to the composite beam when the concrete has hardened and creates a stronger section to support the loadings applied to the finished slab.
Steel designers design the steel frame to approved design standards (the latest being Eurocode 4). These design standards have formulae to calculate the amount of force that can be transferred by each shear stud. When designing the composite beams, the steel designer will calculate how many studs are needed for the beam design based on these values.
Shear stud configuration design rules
The values used by the steel designer for shear stud strength rely on a concrete ‘cone of failure’ around the stud (see photo below) and the studs being spaced to the design rules stated.
There are a number of rules and recommendations from approved design standards and industry best practice which specify spacings, dimensions and layout of studs in order to achieve the required stud resistance. Below is a selection of the most common examples.
When installing shear studs, the length after weld should extend at least 35mm above the top of the main rib of the deck profile. Therefore, the minimum length after weld (LAW) should be 95mm for the TR60+ or R51 and 115mm for TR80+.
Minimum distance from deck rib = 25mm
The recommended minimum concrete cover to the top of the stud is 15mm, this should be increased to 20mm if the shear stud is to be protected against corrosion.
Minimum Flange Thickness to prevent localised bending of the flange at ultimate loading and minimise the chance of weld blow-through = 0.4 x diameter of shear stud = 7.6mm for a standard 19mm stud.
Minimum distance from edge of beam = 30mm