Basic tools of Reinforced Concrete Beam Design

Basic tools of Reinforced Concrete Beam Design Download File

Diaphragm Effects in Retangular Reinforced Concrete Building

Diaphragm Effects in Retangular Reinforced Concrete Building Download File

Pumice concrete for structural wall panels

Structural lightweight aggregate concrete (LWC) has
been used in many civil engineering applications as a very
convenient alternative to conventional concrete. As a matter
of fact its lighter weight permits a saving in dead load
with a reduction in the costs of both superstructures and
foundations. In addition, the better thermal insulation, the
greater fire resistance and the substantially equivalent
sound-proofing properties (in spite of its minor mass compared
to normal weight concrete (NWC) — see e.g. [1])
make it preferable with respect to NWC itself for nonstructural
uses.
In the last five decades the use of LWC has been
extended to structural elements, thanks to the improvement
in performances obtainable (in terms of stiffness, strength
and ductility) by means of appropriate ingredient mix proportions
[2] and appropriate design of the reinforcement.
Naturally, the use of lightweight concrete has been confined
to large structures (where the beneficial influences of
the reduced weight are greater), and, more in particular, to
structures where a high dead load to live load ratio occurs.
Further, the reduced weight may make LWC preferable for
structures in seismic zones, because of the reduced
dynamic actions, and for precast structures, because it
makes it easier to move the elements to be connected.
More recently, lightweight concrete was also applied in
marine structures (offshore structures and ships), and later
for long span bridges, buildings and grandstands [1]. Referring
to buildings, LWC can be used in structural frames,
but it proves to be more suitable for wall system structures,
where the local ductility demand (in seismic zones) and
the required strength of the materials are reduced and the
dead load to live load ratio is very high.
LWC is manufactured by using different kinds of lightweight
aggregates, available in nature or artificially produced,
so that the properties of LWC depend on the properties
of the particular lightweight aggregate being used.
Natural lightweight aggregate sources can be found in
regions characterized by volcanic activity, where porous
rocks (known as pumices), are available. Artificial lightweight
aggregates (like the expanded clay obtained by
thermal treatment of argillaceous materials) are produced
in many countries, the raw materials being very common.
They may exhibit higher resistance than natural
lightweight aggregates, but this favourable result implies
a greater production cost.
Considering the availability of pumice in the world
and its usability as a natural aggregate for concrete, a
research program has been carried out in order to verify
the mechanical properties of the pumice concrete in
relation to the mechanical standards requested by
present-day codes for structural applications, and in
order to observe its behaviour when used for structural
elements. The main results at the actual stage of this
research are presented through the paper. Specifically,
the results of the tests on lightweight pumice stone concrete
(LWPSC) wall panels subjected to vertical and lateral
loads are shown and compared to those obtained
from similar NWC and lightweight expanded clay concrete
(LWECC) wall panels.
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Ductility and linear analysis with moment redistribution in reinforced high strength concrete beams

The evaluation of the ductility of reinforced concrete beams is very important, since it is essential to avoid a
fragile collapse of the structure by ensuring adequate deformation at the ultimate limit state. One of the procedures
used to quantify ductility is based on deformations, namely, the plastic rotation capacity. Knowledge of the plastic rotation
capacity of certain regions of the structure is important for a plastic analysis or a linear analysis with moment redistribution.
An experimental program is described in this article. It is composed of 10 tests designed to study the moment
redistribution and ductility of continuous high-strength concrete beams. Particular care was given to analysing how the
tensile reinforcement ratio and the transverse reinforcement ratio influence the plastic rotation capacity of the beams. A
comparative study was carried out on several codes related to the moment redistribution permitted and the experimental
findings. It was found that some of the recommendations are unsafe. It was also found that high-strength concrete
beams, when properly designed, have enough deformation capacity to be used in plastic analysis.
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CONSTRUCTION MATERIALS

This section describes the basic properties
of materials commonly used in construction.
For convenience, materials are
grouped in the following categories:
cementitious materials, metals, organic materials,
and composites. Application of these materials is
discussed in following sections. In these sections
also, environmental degradation on the materials
are described.
Cementitious Materials
Any substance that bonds materials may be
considered a cement. There are many types of
cements. In construction, however, the term cement
generally refers to bonding agents that are mixed
with water or other liquid, or both, to produce a
cementing paste. Initially, a mass of particles coated
with the paste is in a plastic state and may be
formed, or molded, into various shapes. Such a
mixture may be considered a cementitious material
because it can bond other materials together. After
a time, due to chemical reactions, the paste sets and
themass hardens. When the particles consist of fine
aggregate (sand), mortar is formed. When the
particles consist of fine and coarse aggregates,
concrete results.
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PERENCANAAN DAN PENGENDALIAN MUTU BETON

Dewasa ini pemakaian beton semakin banyak
dijumpai untuk berbagai macam konstruksi
bangunan. Hal ini dikarenakan beton memiliki
berbagai macam keuntungan, antara lain
seperti memiliki kekuatan yang tinggi,
perawatan yang murah, dan dapat dicor sesuai
dengan bentuk dan ukuran yang dikehendaki.
Beton merupakan elemen pembentuk struktur
yang merupakan campuran dari semen,
agregat halus, agregat kasar dan air, dengan
atau tanpa bahan tambahan lainnya. Dalam
hal pencapaian mutu pekerjaan beton terdapat
beberapa faktor yang memengaruhi hasil dari
pekerjaan beton. Faktor-faktor tersebut dapat
kita kelompokkan menjadi faktor internal dan
faktor eksternal. Faktor internal mencakup
mutu bahan-bahan campuran beton. Faktor
eksternal mencakup proses pelaksanaan.
Terjadinya perselisihan, pengulangan
pekerjaan, dan perbaikan pekerjaan sangat
merugikan semua pihak yang terkait, untuk
menanggulangi hal tersebut, maka
pengendalian mutu akibat pengaruh faktor
internal dapat dilaksanakan dengan
mempersiapkan program ”Quality Control”
dengan kegiatan monitoring selama
berlangsungnya pekerjaan dan setelah
selesainya pekerjaan, sedangkan untuk
pengendalian mutu akibat pengaruh faktor
eksternal diperlukan pengawasan yang lebih
aktif dari pihak manajemen konstruksi
terhadap pihak kontraktor dan konsultan.
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Shear Strength of Reinforced Concrete T-Beams without Transverse Reinforcement

The authors have presented an interesting paper on the
shear strength of reinforced concrete T-beams without
transverse reinforcement. However, the discusser would like
to offer the following comments:
1. The authors have mentioned the basic outline of a
derivation of Eq. (1), but Eq. (1) appears to be based on the
neutral axis (NA) located at the center of the beam in a
typical homogeneous rectangular concrete beam. The
authors’ Eq. (2) was a simplification of Eq. (1) based on the
experimental database of reinforced concrete beams, which
is inconsistent with the Rankine’s failure criteria of a plain
homogeneous concrete beam.
Based on ft
= 6 (or 0.1fc ′ ) and assuming the Rankine’s
failure criteria of plain concrete, and by considering various
strength ratios of flexural stress σm versus concrete compressive
stress fc ′ (σm/f ′
c
= 14.2%,
10 the flexural stress σm of a plain
homogeneous concrete beam equals to 114.2%10
of the tensile
strength of plain concrete ft
. Based on the aforementioned
assumptions, the discusser arrived at the authors’ Eq. (2)
without considering the experimental database of reinforced
concrete beams.
Another simplified approach is that Eq. (2) can also be
derived from the current ACI Building Code9
(that is,
authors’ Eq. (5)) by assuming an average depth of NA equals
0.4d11,12
and by substituting c = 0.4d in the authors’ Eq. (5),
which would result in authors’ Eq. (2). Based on the afore-
mentioned two approaches, the discusser believes that there
is no need to have a reinforced concrete beam database, that
is, Fig. 1 and 2. Is this consistent with the shear strength of
reinforced concrete T-beams without transverse reinforce-
ment plain concrete?
fc ′
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STANDARD PRACTICE FOR CONCRETE PAVEMENTS

1. Purpose.
This manual provides information on the
materials and construction procedures for concrete
pavements.
2. Scope.
This manual describes the constituents to
be used in concrete, the procedures to be used in
manufacturing concrete, and the equipment and
procedures to place, texture, and cure concrete for
pavements.
3. Responsibilities, strength, and air content.
a. Responsibility for mixture proportioning.
The responsibility for mixture proportioning must be
clearly assigned to either the contractor or the
contracting officer in the project specifications.
When the contracting officer is responsible for
mixture proportioning, he will approve all concrete
materials as well as determine and adjust propor-
tions of all concrete mixtures as necessary to obtain
the strength and quality of concrete required for the
pavements. Cement will be a separate pay item in
the contract. When the contractor is responsible for
mixture proportioning, he will control all proportions
of the concrete mixture necessary to obtain the
strength and quality of the concrete required for the
pavements, and cement will not be a separate pay
item in the contract. However, the contracting officer
is responsible for approving the quality of all
materials the contractor uses in the concrete.
b. Approval responsibility.
The contracting officer is responsible for approval of all materials,
mixture proportions, plants, construction equipment, and
construction procedures proposed for use by the
contractor. The contractor must submit proposed
mixtures if he is responsible for mixture propor-
tioning; samples of all materials; and detailed
descriptions of all plants, construction equipment,
and proposed construction procedures prior to the
start of construction.
c. Flexural strength.
Structural designs are based on flexural strengths that the
concrete is expected to obtain at 28 days for road pavements
and 90 days for airfield pavements. These ages are not adequate
for quality control in the field since a large amount
of low-strength concrete could be placed before
strength tests on samples revealed the problem.
Correlations can be established between a 14-day
strength and the 28- or 90–day strength used in
design, and this correlated 14-day strength can be
used as a strength check for a more timely concrete
mixture control in the field.
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CONCRETE REPAIR

This handbook describes methods and procedures for maintenance and repair of
concrete pavements. Since surface failure must be corrected at the source, probable causes are
discussed and repair measures described. The principals outlined apply to reinforced and
nonreinforced pavements for roads, airfields, and parking and open-storage areas. Normal
maintenance on concrete pavements consists principally of the care of joints, sealing of cracks,
replacement of random broken slabs or similar sections, and the correction of minor settlement
and drainage faults. Repair consists of the work required to restore a distressed pavement so
that it may be used at its original designed capacity and/or accommodate the current mission as
provided for by applicable service instruction. Additional information can be found in the literature
listed in paragraph 1.3., References. AF Records Disposition. Ensure that all records created
by this handbook are maintained and disposed of IAW AFMAN 37-139, “Records Disposition
Schedule.”
The objective of this handbook is to provide a simple step-by-step “how to”
procedure for concrete pavement repair. Although joint and crack maintenance is one of the
most important maintenance functions to be performed, it will not be covered here. For those
procedures, another handbook has been developed. This handbook will also cover some of the
equipment used in the maintenance and repair of concrete pavements.

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CONCRETE CRACK AND PARTIAL DEPTH SPALL REPAIR

This hand book contains information on current practices (asofSeptember1998)
for the repair of crack sand spalls in concrete pavements as well as on the selection of
materials and equipment.This hand book is intended for use as afield hand book for air field concrete pavement repair for all U.S. Navy, Army, and Air Force facilities ;however, the techniques for repair can beused for other concrete pavements as well.References are provided for additional
information on pavement repair practices not addressed in this manual.Tables1.1. and 1.2. list
applicable American Society of Testingand Materials (ASTM) specification sand American
Concrete Institite (ACI) publications. AF Records Disposition.Ensure that all records created
by this hand book are maintained and disposed of IAW AFMAN 37-139,“Records Disposition
Schedule.”
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Tools for forensic analysis of concrete structures

Computer-aided nonlinear analysis of reinforced concrete structures has undergone tremendous
advancement since initial applications about four decades ago. Much research activity has occurred
in the realm of constitutive modeling of reinforced concrete and in the development of sophisticated
analysis algorithms. These advancements are well documented in various state-of-the-art reports (for
example, ASCE (1982)), and are still the subject of many specialty symposia and workshops. One
particularly powerful and popular approach to advanced modeling involves the use of nonlinear
finite element analysis (NLFEA) techniques. The development of such procedures has progressed to
the point where they are becoming practical tools for design office engineers.
Advanced analytical procedures are finding application as useful forensic analysis tools in
relation to damaged or ageing structures. NLFEA procedures can be used to obtain an assessment
of the safety and integrity of damaged or deteriorated structures, or structures built to superceded
codes, standards, or practices deemed to be deficient today. They can be of value in assessing the
behavior expected from retrofitted structures or in investigating and rationally selecting among
various repair alternatives. In cases of structural failure or collapse, NLFEA procedures can be
invaluable in determining the contributing factors and in suggesting remedial measures for future
designs.
There remain some concerns with the use of these advanced methods, however. Accurate
modeling of the complex behavior of reinforced concrete remains elusive, with many conflicting
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Analysis of the weightiness of site effects on reinforced concrete (RC) building seismic behaviour The Adratown example (SESpain)

The softness of the ground surface and the thickness of surface sediment shave been observed
as two important local geological factors that affect the level of earthquake shaking.Their local
variations can lead to spatial seismic intensity differences and may have a remarkable influence on
the level of building damage and on significant earthquake damage distribution even in the cases
of moderate earthquakes.
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