2.4.1 Live load
It is the vertical load in the design of structure. Live loads are movable loads which are keep on changing continuously. These loads are assumed to be produced by the intended occupancy or use of the building except the construction and environmental loads.
2.4.2 Dead load
Dead load considered as vertical load. The magnitude, direction, and position of dead load remain constant and transferred to structure throughout the life span. It is also known as permanent or static load which are mostly associated with the self-weight of the structure. In addition, it may include finishes, built-in cupboard, permanent non-structural partition and so on. Moreover, dead load consists of other permanent part of the building such as roof, wall, column and beam. Dead load calculated by multiply the volume with unit weight of material.
2.4.3 Wind load
Wind load considered as a horizontal load which caused by the air movement to structure. The impact of air and wind to building is directly proportional with the height of the building. Moreover, the utilization of light material and shape affect by the flow of air. There are two factors that wind load depends on it in the calculation which are size of building and velocity of wind.
2.4.4 Earthquake load
It is also Known as seismic load which constitute to both horizontal and vertical load on the building. The building should be analyzed and designed carefully to ensure that when an earthquake occurs, the building will not fail. In addition, design of the structure affected by Areas with great seismic activity for example, New Zealand, north and south American and other Mediterranean countries.
2.5 Design Philosophies
A set of assumptions and procedures to have a safe, economic and serviceable building based on the carried loads by the material and the stress-strain curve of the material. There are three major methods of design founded in different periods as introduced below from the oldest one to the latest method.
Stress-strain curve is one of the standards based on experiments and tests for specified material that showing its behavior after applying load increasing continuously until the material collapse. The slope of the linear relationship is equals to the Modulus of Elasticity.
2.5.1 Working stress method
It is one of the design philosophies that used for reinforced concrete, structural steel and timber design by civil engineers. This method follows linear stress-strain behavior because both materials concrete and steel are acting together elastically. The stress in concrete and steel can be determined by using a factor which called modular ratio. Moreover, in working stress method the structure is designed to never exceed elastic limit thus if the structure reaches the plastic range, it will fail immediately. The main disadvantages of working stress method is that uneconomic and complicated procedures of the calculation.
2.5.2 Load factor method
It is also called ultimate load method or ultimate strength method. This method came in practice in 1957 to overcome working stress method. Ultimate load is the load which is cause failure to part or the whole structure. When designing by ultimate strength method, the service load is increased by multiplying it with load factor to get the ultimate loads. The assumption in this method is that when the section is subjected to bend the compressive stress distribution is non-linear and the compressive stress diagram may be assumed as parabola, rectangle, trapezoidal or any other shape. The material in this method is not linear-elastic which mean that various loads can have various safety factors. The calculations are based on the ultimate load and stress conditions at the site of impending collapse is analyzed. Compared with elastic design method the ultimate strength of the material is considered and it will get many slender sections of column and beams and the load factor method is more economical than the work stress method. The reinforcement concrete structure designed by this method becomes unsafe and unserviceability because of deflection and cracking in the structure.
2.5.3 Limit state design
Limit state design is known as load and resistance factor design too. It is considering the serviceability at the working stress and the safety of the ultimate load. Working stress and load factor technique are combined in this design philosophy. The limit state is a condition just ahead the failure. It was developed based on a research led by Professor N.S. Streleski in USSR (Union of Soviet Socialist Republics) and was introduced in USSR building regulation in 1995. This type of design can withstand all the loads safely. Also, to make sure that not become unqualified for the uses which they are designed. One of the most important advantages of this method is the economical and most of codes are prefers to use this method instead of using working stress method.
The sorts of limit state are:
• Ultimate Limit State (ULS): it consists of fatigue, bending, shear force etc.
• Serviceability Limit State (SLS): it consists of deflection, cracking, vibration, etc.
2.6 Building Codes
Environment conditions, population and growth economy are some factors affecting the life style and habits of people, who wants modern house or traditional one or any other properties that can be easy or difficult to do it by the architect and the engineer. Anywise, having guidelines and specifications to follow, help in preparing designs that are safe, comfortable and more economical than designs prepared randomly.
Formulas, equations, coefficients, assumptions and rules etc… that are combined all together forming what is called as code of practice based on the covered subjects or specialization for example, building code is a code or standards created for structures and buildings, and it is prepared by a group of qualified and experienced people proposed to all the country for following it legally otherwise, there are punishments for those who do not follow the code specialized for the region.
However, graphs and table assist the users for a particular code of practice in how to use it in correct way avoiding any mistakes that can be fall in, by giving the procedures to reach the desirable and acceptable results with providing different numerical examples to gain more idea about the steps of designing. This called as the Aid design.
Each code of practice has a name can be minimized by taking the first letters of the name following by the specified number for the type of structure or the standard which are covered under that section, and often concluding with the year of publish.
2.6.1 American concrete institute
In early 1900’s, American concrete institute began to study and prepare the requirements and standards for building with different functions and materials. This can make others to take it a good decision as for estimating and designing because of the age of this organization. However, ACI introduced the design method to be ultimate strength method at 1956. Although in 1995 the limit state method was adopted on Building Code Requirements for Structural Concrete (ACI 318-95).
Building Code Requirements for Structural Concrete (ACI 318-14) and The Reinforced Concrete Design Handbook (ACI SP-17(14)) will be used in this project which are the latest revisions of codes of practice and aids design. This code has all required data, it does not have separate code for loads combination.
2.6.2 British standard
It is one of the codes that used as a basis for other codes and materials specifications furthermore, it aims to achieve an acceptable probability that structures being designed will perform satisfactorily during their intended life. First published was in August 1985 and the second edition in March 1997 which recommended the limit state method to use in design.
Though, Structural use of concrete-Part 1: Code of practice for design and construction (BS 8110-1:1997) would be in the comparison of design between the codes. Moreover, Part 3: Design charts for singly reinforced beams, doubly reinforced beams and rectangular columns (BS 8110-3:1985) as an aid design that assist the British standard for Structural use of concrete.
For different loads there are codes and specifications should be followed which are, code of practice for dead and imposed load (BS 6399 -1), code of practice for wind load (BS 6399 -2), and Design of structures for earthquake resistance (BS EN 1998 -1).
2.6.3 Indian standard
The first version of this standard was published in 1953 which derived from many building codes such as, BS for most of formulation and some clauses from ACI, Standards Association of Australia (AS), Deutschcs lnsritut fur Normung E.V. (DIN) and International Du Bclon (CEB-FIP). It revised many times, but in 1978 the third reversion include the limit state design. However, every reversion had many changes in different parts depending on the concrete technology and reinforcement conditions.
Plain and Reinforced Concrete Code of Practice (IS 456:2000), it is the fourth reversion which is one of the codes of practice that will be used in design comparison. In addition, Design Aids for Reinforced Concrete for IS 456 (SP 16) is the published paper in 1978 that support IS 456 users.
Code of Practice for Design Loads (Other Than Earthquake) For Buildings and Structure (IS 875- Part 2), Dead Loads- Unit Weights of Building Materials and Stored Materials (IS 875- Part 1), Wind Loads on Buildings and Structures (IS 875- Part 3), and Criteria for Earthquake Resistant Design of Structures (IS 1893) are the codes used for loading in IS.
2.7 Structural Software
Nowadays, complex and complicated structures that are designed and sketched by the architects need to qualify and apply it safely and economically. However, structural softwares are applications developed by engineers and developers with the help of civil engineers that can used for analyzing or designing a whole building or separates structural element according to the specified code in short time comparing with solving manually.
Telka Tedds is a known software that can be used by engineers and students for designing the structural elements, it provides all the calculations, equations and drawings. However, this can help the interested people on reducing their risks and ensuring that elements can be built it safely. As students, it can help in comparing the results and checking it.