RCC beams structural elements are designed to carry transverse external loads that cause bending moment, shear forces and in some cases torsion across their length. Concrete is strong in compression and very weak in tension. Steel reinforcement is used to take up tensile stresses in reinforced concrete beams.
Many different types of structures and components of structures can be built using reinforced concrete including slabs, walls, beams, columns, foundations, frames and more.Reinforced concrete can be classified as precast or cast-in-place concrete. Designing and implementing the most efficient floor system is key to creating optimal building structures. Small changes in the design of a floor system can have significant impact on material costs, construction schedule, ultimate strength, operating costs, occupancy levels and end use of a building.
Reinforced concrete, as a composite material, has occupied a special place in
the modern construction of different types of structures due to its several
advantages. Italian architect Ponti once remarked that concrete liberated us from
the rectangle. Due to its flexibility in form and superiority in performance, it has
replaced, to a large extent, the earlier materials like stone, timber and steel.
Further, architect's scope and imaginations have widened to a great extent due
to its mouldability and monolithicity. Thus, it has helped the architects and
engineers to build several attractive shell forms and other curved structures.
However, its role in several straight line structural forms like multistory
frames, bridges, foundations etc. is enormous.
The design of these modern reinforced concrete structures may appear to be
highly complex. However, most of these structures are the assembly of several
basic structural elements such as beams, columns, slabs, walls and foundations.
Accordingly, the designer has to learn the design of these basic reinforced
concrete elements. The joints and connections are then carefully developed.
Design of reinforced concrete structures started in the beginning of last century
following purely empirical approach. Thereafter came the so called rigorous
elastic theory where the levels of stresses in concrete and steel are limited so
that stress-deformations are taken to be linear. However, the limit state method,
though semi-empirical approach, has been found to be the best for the design of
reinforced concrete structures
Objectives of the Design of Reinforced Concrete
Structures:
Every structure has got its form, function and aesthetics. Normally, we consider
that the architects will take care of them and the structural engineers will be
solely responsible for the strength and safety of the structure. However, the
roles of architects and structural engineers are very much interactive and a
unified approach of both will only result in an "Integrated" structure, where
every material of the total structure takes part effectively for form, function,
aesthetics, strength as well as safety and durability. This is possible when
architects have some basic understanding of structural design and the structural
engineers also have the basic knowledge of architectural requirements. Both the engineer and the architect should realize that the skeletal structure
without architecture is barren and mere architecture without the structural
strength and safety is disastrous. Safety, here, includes consideration of reserve
strength, limited deformation and durability. However, some basic knowledge
of architectural and structural requirements would facilitate to appreciate the
possibilities and limitations of exploiting the reinforced concrete material for
the design of innovative structures.
Before proceeding to the design, one should know the objectives of the design
of concrete structures. The objectives of the design are as follows:
1.
The structures so designed should have an acceptable
probability of performing satisfactorily during their intended life:
This objective does not include a guarantee that every structure must perform
satisfactorily during its intended life. There are uncertainties in the design
process both in the estimation of the loads likely to be applied on the structure
and in the strength of the material. Moreover, full guarantee would only involve
more cost. Thus, there is an acceptable probability of performance of structures
as given in standard codes of practices of different countries.
2. The designed structure should sustain all loads and deform
within limits for construction and use:
Adequate strengths and limited deformations are the two requirements of the
designed structure. The structure should have sufficient strength and the
deformations must be within prescribed limits due to all loads during
construction and use. The structure having insufficient strength of concrete
which fails in bending compression with the increase of load, though the
deformation of the structure is not alarming. In another situation where the
structure, having sufficient strength, deforms excessively. Both are undesirable
during normal construction and use.
However, sometimes structures are heavily loaded beyond control. The
structural engineer is not responsible to ensure the strength and deformation
within limit under such situation. The staircases in residential buildings during
festival like marriage etc., roof of the structures during flood in the adjoining
area or for buildings near some stadium during cricket or football matches are
some of the examples when structures get overloaded. Though, the structural
designer is not responsible for the strength and deformations under these
situations, he, however, has to ensure that the failure of the structures should give sufficient time for the occupants to vacate. The structures, thus, should
give sufficient warning to the occupants and must not fail suddenly.
3. The designed structures should be durable:
The materials of reinforced concrete structures get affected by the
environmental conditions. Thus, structures having sufficient strength and
permissible deformations may have lower strength and exhibit excessive
deformations in the long run. The designed structures, therefore, must be
checked for durability. Separate checks for durability are needed for the steel
reinforcement and concrete. This will avoid problems of frequent repairing of
the structure.
4. The designed structures should adequately resist to the effects
of misuse and fire:
Structures may be misused to prepare fire works, store fire works, gas and other
highly inflammable and/or explosive chemicals. Fire may also take place as
accidents or as secondary effects during earthquake by overturning kerosene
stoves or lantern, electrical short circuiting etc. Properly designed structures
should allow sufficient time and safe route for the persons inside to vacate the
structures before they actually collapse.
How to fulfill the objectives?
All the above objectives can be fulfilled by understanding the strength and
deformation characteristics of the materials used in the design as also their
deterioration under hostile exposure. Out of the two basic materials concrete
and steel, the steel is produced in industries. Further, it is available in form of
standard bars and rods of specific diameters. However, sample testing and
checking are important to ensure the quality of these steel bars or rods. The
concrete, on the other hand, is prepared from several materials (cement, sand,
coarse aggregate, water and admixtures, if any). Therefore, it is important to
know the characteristic properties of each of the materials used to prepare
concrete. These materials and the concrete after its preparation are also to be
tested and checked to ensure the quality. The necessary information regarding
the properties and characteristic strength of these materials are available in the
standard codes of practices of different countries. It is necessary to follow these clearly defined standards for materials, production, workmanship and
maintenance, and the performance of structures in service.
RCC DESIGN BY JACK C MCCORMAC
RCC DESIGN BOOK BY AKHTEM-AL MANASEER
RCC DESIGNER HANDBOOK
RCC DESIGN BY NPTEL
RCC DESIGN BY FABER
RCC DESIGN BY FABER AND BOWIE
RCC DESIGN BY JOHN BROOKS
RCC ECONOMICAL DESIGN
RCC DESIGN BOOK
RCC BASIC DESIGN BOOK
