All the Formulas and calculation used in technical & design calculation in Civil Engineering and the related fields of Civil Engineering are incorporated in this Book.
American Society for Civil Engineer (ASCE) has published the latest version (ASCE 7-22) for Minimum Design Load and Associated Criteria for Building and Other Structure describes the means for determining design loads including dead, live, soil, flood, tsunami, snow, rain, atmospheric ice, seismic, and wind loads and their combinations for general structural design. Structural engineers, architects, and building code officials will find the structural load requirements essential to their practice.
Download the Document for Study and Design purpose only.
Following are some of the major International Building Codes have been discussed.
(1) General Building Codes
Each cover all aspects of building designing and construction. These codes use by structural designers to make safe and economical their structure while follow the criteria, data required the structural designing and bylaws of the countries they want to design and construct that structure. The following three (3) Codes are the International codes generally follows in different countries in the world for Civil Engineering Structure Designing. Almost every countries has its own building codes which is derived and modified these International Codes according to their countries geography, earthquakes and some other factor and parameters. These Codes specify the requirements of the governmental bodies for minimum design loads on structures and mininmum standards for construction.
(a) Uniform Building Code (UBC-97)
This is an international building code last updated in 1997 that’s why it is called UBC-97. This code is generally applied in USA and Asian Countries. It can be use anywhere in the world if it meets the criteria, data required by the designer and comply with the national and local governments bylaws. So every countries derived and modified these International Codes according to their countries geography, earthquakes and some other factor and parameters. They cannot apply these codes blindly.
UBC-97
(b)International Building Code (IBC-2000)
This code was established in 2000, that’s why it is called IBC-2000. This code is also applicable in different countries throughout the world if it meet the criteria, data required and the local government acceptance. So every countries derived and modified these International Codes according to their countries geography, earthquakes and some other factors and parameters. They cannot apply these codes blindly.
International Building Code
(c) Eurocode
This is an international building code. It is normally applicable in European countries, but it can also be apply in any countries if it meet the criteria, data required and the local government acceptance. So every countries derived and modified these International Codes according to their countries geography, earthquakes and some other factors and parameters. They cannot apply these codes blindly.
Eurocode
National Codes
Almost every country has its own building codes which is derived and modified these International Codes according to their country geography, earthquakes and some other factors and parameters. They cannot apply these codes blindly. So these derived and modified codes for the specific countries is called National Codes. I want to mention some examples of National Codes.
(a) Building Code of Pakistan (BCP)
BCP code is for Pakistan only and it is derived from UBC-97 because the data and information required for Pakistani Structure Designer was available in UBC-97. Especially the date required regarding earthquakes, so first of all Pakistan publish their Code in 2007 which is called “BCP-SP-07”. So they make little changes in the UBC-97 and publish their own code called BCP.
BCP-SP-07
(B) Indian Standards Code (IS)
IS is the Indian codes for constructions and it is normally applicable in India only unless you make it checked all the criteria to use in any other countries. IS is further divided in many codes normally used for Structural Reinforced Concrete is IS-456-2000, National Building Code (NBC), Bureau of Indian Standards (BIS).
Bureau of Indian Standards
(2) Design Codes or Building Codes for Specific Materials
These codes the cover design and Construction of structures using specific materials. These are the general guideline codes for specific materials. Design codes provides detailed technical standards and are used to established the actual structure design. The ultimate responsibility lies on Structural Engineer that how to apply these standards and his/her efficiency to Design any structure. These Codes include but not limited to:
ACI: American Concrete Institute (Used for RCC structural materials, elements and structures all over the world for design of specific materials guidelines)
AISC: American Institute of Steel Construction ( Manual for Steel Construction structures uses all over the world for general design guidelines)
AASHTO: American Association of State Highway and Transportation Officials (Used for Road designing and Construction all over the world but it should comply with country geography and other parameters).
AREA: American Railway Engineering Association (Manual for Railway Engineering).
AFPA: American Forest and Paper Association ( National Design Association for Wood Construction).
ASTM: American Society for Testing Materials ( general guideline and standards procedures for Testing materials use during Construction)
The three(3) major Design Philosophies used while designing of RCC, Steel or any type of Civil Engineering Structures are discussed here:
ASD (WSD or WSM)
ULM (USD)
LRFD (LSD or LSM)
(1) ASD (WSD)
Allowable Stress Design (ASD) also called Working Stress Design/method (WSD) is basically Allowable Strength Design. In this method we apply a Factor of Safety (FoS) on ultimate strength of the material as whole and compare the results with the actual load that actually to be applied during the life span of the structure, if actual load < allowable load then the design is OK. This method only satisfy the serviceability of the structure or Serviceability Limit State (SLS).
Drawbacks
ASD method uses only the elastic region of stress-strain curve of materials due to which most of the strength acts as a reserve.
ASD gives an uneconomical dimensions of the structural element.
ASD doesn’t show any sign about collapse of structure, it means doesn’t satisfy the Ultimate Limit State.
ASD uses only material strength reduction factors in the form of FoS: Which are Given below:
Factor of Safety (FoS) for Concrete= 3
Factor of Safety (FoS) for Steel= 1.78
Stress-Strain Curve for Concrete
(2) ULM (USD 0r Load factor)
Ultimate Load Method (ULM) or Ultimate Strength Design (USD) or Load Factor is the design philosophy of design structures in which load increasing factor is used while calculating different loads combinations and these factors generally (>1) to increase loading so is to adjust the uncertainties occurring in load applications. Some Load Combination According to ASCE and UBC-97 are Listed here:
ASCE Load Combinations
1.4D
1.2D + 1.6L + 0.5(Lr or S or R)
1.2D + 1.6(Lr or S or R) + (L or 0.5W)
1.2D + 1.0W + L+0.5(Lr or S or R)
1.2D + 1.0E + L +0.2S
0.9D + 1.0W
0.9D + 1.0E
UBC-97 Load Combinations
1.4D
1.2D + 1.6L +0.5 (Lr or S)
1.2D +1.6 (Lr or S) + (f1L or 0.8W)
1.2 D + 1.3W + f1L + 0.5 (Lr or S)
1.2 D + 1.0E + (f1L + f2S)
0.9D ± (1.0E or 1.3W)
“Load factor is the ratio of ultimate strength to the service loads“
The ULM makes it possible to consider the effects of different loading acting simultaneously thus solving the shortcomings of WSM (WSD). As the ultimate strength of the material is considered we will get much slender/thinner sections for different elements of the structures e.g columns, beams etc. In this method we use the non-linear method of stress-strain curves for concrete and steel.
Stress-Stain Curve for Steel Rebar
Drawbacks
This method doesn’t satisfy the Serviceability Limit State (SLS).
This method gives very thin sections of members which is vulnerable to severe cracks and damaged.
This method only consider load factors while ignoring the strength of materials.
(3) LRFD (LSD or LSM)
Load and Resistance Factor Design(LRFD) or Limit State Method/Design (LSM or LSD) is the most advanced method while design any civil engineering structures. It considered both factored loads and material strength reduction factors partially.
There are Two Limit States which is satisfied in LRFD (LSM) Method:
Ultimate Limit State: It considers strength, overturning, fatigue, sliding etc.
Serviceability Limit State: It Considers Cracks width, deflection, vibration etc.
This method use to multiply partial safety factors for required safety at ultimate load and serviceability at working load.
Partial Safety Factor for Materials:
The strength of concrete in actual structure is taken as (0.67*characteristic strength), i.e 0.67fck. The partial safety factor for (Ultimate limit state) for concrete is 1.5 and that for steel is 1.15. The value for concrete higher because it has more variability and uncertainties compared to steel. The partial safety factor ( for serviceability limit state) for concrete and that for steel is taken is 1. This is taken unity as we are interested in estimating the actual deflections and crack widths during service loads.
Partial Safety Factor for Loads:
Various load Combinations are used and it may be different in different design codes.
For Ultimate Limit States:
UL= 1.5(DL+LL)
UL=1.5(DL+QL) or 0.9DL+1.5QL (QL: Earthquake/Wind Load)
UL=1.2(DL+LL+QL) (1.2 because the probability of three loads reaching its peak together are less)
For Serviceability Limit States:
SL= 1.0 (DL+LL)
SL=1.0 (DL+QL)
SL=1.0DL+0.8LL+0.8QL
The load factor is taken as 0.8 in the third case as the probability of wind load or earthquake load acting with the peak of live load is less. For all other cases we consider the safety factor is 1.0 because we consider the serviceability of structure here.
So Why LRFD/LSM Design Philosophy is more reliable?
LRFD/LSM is a more reliable and statistical based method for predicting both loads and material strengths.
Whereas the allowable stress safety factors were based on engineering judgement and past experiences.
This method gives you an economical, safer & serviceable structural elements/members.
The shortcomings in the previous methods were addressed and rectified here on a more rational basis.
The continuous layer of an impervious material, which is provided in between the source of dampness and part of the structure is called a Damp-Proof Course.The function of providing damp proof course is to prevent dampness and it is laid either horizontally or vertically. Horizontal D.P.C is generally laid 150 to 200 mm above the ground level on the external walls and at plinth level in case of internal walls of a building. While Vertical D.P.C is provided to connect the horizontal D.P.C in the external walls with the floor level to check the flow of moisture from the underside of a floor into the walls.
D.P.C
By Surface Treatment
This method consists in painting the exposed surface of the wall with a water repellant paint. Material to be used for painting the wall surface must be durable and effective to check the absorption of moisture by the wall.
By Integral Water-Proof Construction
This method consists of adding certain compound in the mortar or concrete to make it more dense by filling the pores through chemical action or mechanical effect. If 5% sunlight soap is added in the water to be used for preparing the mortar, the pores get clogged and a coating of water repellant substance sticks to the wall surface which makes it sufficiently Damp-Proof.
By Special Devices
Dampness can be prevented by using some special devices which are given below:
By constructing the external walls of sufficient thickness.
By using the bricks of good quality for constructing the external walls.
By building the walls in rich cement mortar.
By providing string courses and cornices.
By fixing the down water pipes in sufficient number so that water may not leak through the junction of wall and the roof.
Civil-Ideas 