Finite Element Modeling of RCC voided Beam and it’s comparison with conventional RCC beam

International Journal of Engineering Science Invention
ISSN (Online): 2319 – 6734, ISSN (Print): 2319 – 6726
www.ijesi.org ||Volume 5 Issue 4|| April 2016 || PP.55-59
www.ijesi.org 55 | Page
Finite Element Modeling of RCC voided Beam and it’s
comparison with conventional RCC beam
Sameer Kishor Bhole1
, Prof. M.R. Wakchaure2
1
PG Student, Faculty of Civil Engineering, Amrutvahini College of Engineering, Sangamner / Savitribai Phule
Pune University, Pune, India.
2
Prof. M.R. Wakchaure, Faculty of Civil Engineering, Amrutvahini College of Engineering, Sangamner /
Savitribai Phule Pune University, Pune, India.
ABSTRACT : In the construction of modern buildings, a network of pipes and ducts is necessary to
accommodate essential services like water supply, sewage, air-conditioning, electricity, telephone, and
computer network. Usually, these pipes and ducts are placed underneath the beam soffit and, for aesthetic
reasons, are covered by a suspended ceiling, thus creating a dead space. The provision of transverse openings
in floor beams to facilitate the passage of utility pipes and service ducts results not only in a more systematic
layout of pipes and ducts, it also translates into substantial economic savings in the construction of a multi-
storey building.
KEYWORDS – ANSYS, Beam (Reinforced Concrete), Serviceability, Structural design, voided beam.
I. Introduction
Usually pipes and ducts are placed underneath the beam soffit which is necessary to accommodate essential
services like water supply, sewage, air-conditioning, electricity, telephone, and computer network. Passing these
ducts through transverse openings in the floor beams leads to a reduction in the dead space and results in a more
compact design. For small buildings, the savings thus achieved may not be significant, but for multistory
buildings, any saving in story height multiplied by the number of stories can represent a substantial saving in
total height, length of air-conditioning and electrical ducts, plumbing risers, walls and partition surfaces, and
overall load on the foundation.
It is obvious that inclusion of openings in beams alters the simple beam behavior to a more complex one. Due
to abrupt changes in the sectional configuration, opening corners are subject to high stress concentration that
may lead to cracking unacceptable from aesthetic and durability viewpoints. The reduced stiffness of the beam
may also give rise to excessive deflection under service load and result in a considerable redistribution of
internal forces and moments in a continuous beam. Unless special reinforcement is provided in sufficient
quantity with proper detailing, the strength and serviceability of such a beam may be seriously affected.
In extensive experimental study, Many Researchers considered openings of circular, rectangular, diamond,
triangular, trapezoidal and even irregular shapes. However, circular and rectangular openings are the most
common ones in practice. When the size of opening is concerned, many researchers use the terms small and
large without any definition or clear-cut demarcation line. From a survey of available literature, it has been
noted that the essence of such classification lies in the structural response of the beam. When the opening is
small enough to maintain the beam-type behavior or, in other words, if the usual beam theory applies, then the
opening may be termed as small opening. In contrast, large openings are those that prevent beam-type behavior
to develop. Thus, beams with small and large openings need separate treatments in design.
II. System Development
ANSYS is useful to final element simulations for RCC structure we use SOLID 186 for Concrete, LINK 8
for Rebar (Reinforcement),CONTA 174 And TARGE 173 to define contact between them. Following are the
elements are used for the simulation of RCC beam.
2.1 SOLID186 Element Description:
SOLID186 is a higher order 3-D 20-node solid element that exhibits quadratic displacement behavior. The
element is defined by 20 nodes having three degrees of freedom per node: translations in the nodal x, y, and z
directions. The element supports plasticity, hyperelasticity, creep, stress stiffening, large deflection, and large
strain capabilities. It also has mixed formulation capability for simulating deformations of nearly incompressible
elastoplastic materials, and fully incompressible hyper elastic materials.

Finite Element Modeling of RCC voided…
Fig. 1
2.2 LINK8 3-D Spar:
LINK8 is a spar which may be used in a variety of engineering applications. Depending upon the
application, the element may be thought of as a truss element, a cable element, a link element, a spring element,
etc. The three-dimensional spar element is a uniaxial tension-compression element with three degrees of
freedom at each node: translations in the nodal x, y, and z directions. As in a pin-jointed structure, no bending of
the element is considered. Plasticity, creep, swelling, stress stiffening, and large deflection capabilities are
included. See Section 14.8 in the ANSYS Theory Reference for more details about this element. A tension only
compression-only element is defined as LINK10.
Fig. 2
2.3 CONTA174 and TARGE170:
The 3-D contact surface elements (CONTA173 and CONTA174) are associated with the 3-D target segment
elements (TARGE170) via a shared real constant set. ANSYS looks for contact only between surfaces with the
same real constant set. For either rigid-flexible or flexible-flexible contact, one of the deformable surfaces must
be represented by a contact surface.
If more than one target surface will make contact with the same boundary of solid elements, you must define
several contact elements that share the same geometry but relate to separate targets (targets which have different
real constant numbers), or you must combine two target surfaces into one (targets that share the same real
constant numbers).
Real constant R1 is used only to define the radius if the associated target shape (TARGE170) is a cylinder,
cone, or sphere. Real constant R2 is used to define the radius of a cone end at the second node.
Fig. 3

a. Analysis of Ultimate Strength:
Fig. 4, Beam with a large opening under bending and shear.
III. Problem Statement
Fig. 5, Reinforcement details of beams
The RCC beam of 2900 mm span is experimentally casted by Mansur et al in 1999, all the specifications and
loading pattern is mention in fig. 5.
Fig. 6
Fig. 7

3.1 Material Properties :
Grade of steel 415 MPA and Grade of Concrete M30, cylindrical compressive strength of concrete 30.8
MPA, assume service load is equal to ultimate load of beam / 1.7.
IV. Performance of Analysis:
The experimental test results are validated with finite element analysis model using Ansys WORKBENCH
14. The errors are founds to be 20 % in given simulations.
Graph 1
Fig. 8, Max. normal stress occurred at l/4 due to voids
Fig. 9, Max. shear stress developed at slab beam connection
Fig. 10, Total shear force

The Maximum mid span deflection of beam with circular opening, large rectangular opening and
conventional RCC beam is plotted in Graph 1. It was observed that mid span deflection, normal stress, shear
stress is comparatively less in conventional RCC beam. In RCC beam with circular opening first crack occurred
at 269 KN and assume service load was 275 KN which is nearly same.
V. Conclusion
• This paper brief above comparison of RCC conventional beam with RCC beam having transverse web
opening subjected to combined bending and shear.
• In various construction, ducts are provided for different utilities, due to duct deflection, deformation,
normal stress, shear stress increase due to voids additional reinforcement and its design are need to be
provided in IS codes, in later stage of project type of openings are studied (Circular and rectangular
openings.).
• Maximun normal stress are observed near opening of beam hence additional transversed shear
reinforcement required to reduce normal stress.
References
[1] ANSYS. ANSYS User's Manual Revision 14, ANSYS.
[2] IS 1893 - Part 1, Indian Standard Criteria for Earthquake Resistant Design of Structures, Bureau of Indian Standards, New Delhi,
India, 2002.
[3] IS 456, Indian Standard Plain and Reinforced Concrete Code of Practice, Bureau of Indian Standards, New Delhi, India, 2000.
[4] Mansur, M.A., Design of Reinforced concrete beams with web openings. proceedings of the 6th Asia-Pacific Structural
Engineering and Construction Conference (APSEC 2006), 5 - 6 September 2006, Kaula Lumpur, Malaysia.

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