Lack of a scientific design approach for repair and rehabilitation of corroding
reinforced concrete infrastructure has resulted in significant financial and social costs.
This experimental program was primarily undertaken to examine the corrosion process in
reinforced concrete repair, which has different characteristics as compared with corrosion
in new construction. The program was designed to gain a deeper understanding of how
certain restoration strategies may lead to problems of electrochemical incompatibility and
result in ineffective corrosion mitigation.
Fifteen specimens, 1m by 1m by 0.2m, were cast to represent a section of a
deteriorating reinforced concrete bridge deck slab. The central portion was uniquely
designed to simulate the deterioration caused by corrosion activity in a bridge deck slab.
After initiating corrosion using wetting and drying cycles with 15 %salt solution, each
specimen was subjected to a unique restoration strategy. The wetting and drying cycles
continued, and a monitoring program was established to observe the corrosion activity of
each specimen.
The results corroborate current research, that patch repairs can trigger the
formation of a macrocell corrosion cell, or a ring of active corrosion surrounding the
repaired zone. In addition, the results from the electrochemical testing revealed sharp
differences in the corrosion behaviour of the different restoration strategies. However, the
physical evidence of minimal corrosion for all four specimens that were demolished at
the end of the testing period, reveals a discrepancy with the electrochemical testing
results.
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Understanding the properties of concrete under high temperature is essential
to enhance the fire resistance of reinforced concrete structures (RCS) and to provide
accurate information for fire design of RCS. Extensive studies on this important topic
were performed previously. However, the properties of concrete under high
temperature have not been fully understood. Even if there are numerous experimental
and theoretical results available in the literature, contradictions among observations
exist and need to be reconciled.
The studies performed in this thesis can be largely classified as four topics.
Among the four topics, two topics are experimental studies and the other two topics
are theoretical models.
The first experimental study is to find the effects of temperature and moisture
on deformation of concrete. Due to the dependency of the moisture on temperature, it
is not easy to distinguish experimentally the effects of temperature and moisture on
the deformation of concrete. Usually, the thermal strain of concrete, which is called
Conventional Thermal Strain (CTS) in this study, is obtained by measuring the
displacement change without moisture control. In this study, CTS, the strain caused
by temperature increase under constant humidity (Pure Thermal Strain: PTS), and the
strain caused by moisture change under constant temperature (Pure Hygro Strain:
PHS) are measured continually over time. From the data analysis based on the
measured strains, the thermo-hygro coupling effect in the temperature is obtained.
Previous experimental studies on concrete under high temperatures have
mainly concentrated on the strength reduction of concrete, even though the loss of
durability of concrete can severely reduce the remaining service life of the structure.
In the second experimental study, the strength, stiffness, and durability performance
of concrete subjected to various heating and cooling scenarios are investigated.
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This research study focuses on evaluating the design of HSC prestressed bridge
girders. Specifically there were three major objectives. First, to determine the current
state of practice for the design of HSC prestressed bridge girders. Second, to evaluate
the controlling limit states for the design of HSC prestressed bridge girders and identify
areas where some economy in design may be gained. Third, to conduct a preliminary
assessment of the impact of raising critical design criteria with an objective of increasing
the economy and potential span length of HSC prestressed girders.
The first objective was accomplished through a literature search and survey. The
literature search included review of design criteria for both the AASHTO Standard and
LRFD Specifications. Review of relevant case studies of the performance of HSC
prestressed bridge girders, as well all as of important design parameters for HSC were
carried out. In addition, a survey was conducted to gather information and document
critical aspect of current design practices for HSC prestressed bridges
The second objective was accomplished by conducting a parametric study for
single span HSC prestressed bridge girders to mainly investigate the controlling limit
states for both the AASHTO Standard (2002) and LRFD (2002) Specifications.
AASHTO Type IV and Texas U54 girder sections were considered. The effects of
changes in concrete strength, strand diameter, girder spacing and span length were
evaluated.
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Author: Robert J. Dinan | Size: 6.77 MB | Format:PDF | Quality:Scanner | Publisher: Robert J. Dinan | Year: 2005 | pages: 149
Steel studs have the desired combination of strength and ductility crucial to the
design of efficient blast resistant wall systems. Designing connection details that utilize
the ductility of the steel studs is critical to the performance of the system. The
development of prediction methodologies and engineering design tools is essential to
provide engineers with a proven method to design these types of blast resistant structural
systems. This research focused on developing a method to use steel studs in blast
resistant exterior wall systems to provide protection to building occupants in case of a
bomb detonation near the structure. A connection method was developed to anchor the
steel studs to the floor and ceiling of the structure to prevent failure at the connections
and allow the stud to absorb energy through plastic deformation. An analytical static
resistance function was developed to predict the midpoint deflection of the steel stud wall
subjected to uniformly distributed loads. This resistance function predicts the response of
the wall as the behavior transitions through several behavior regions: flexural bending,
plastic hinge formation, tension cable behavior, and ultimate failure. The analytical static
resistance function was validated using data from full-scale quasi-static uniform loading
experiments. This resistance function was incorporated into a single degree of freedom
(SDOF) dynamic model, which predicts the response of a steel stud wall system
subjected to blast loads. This dynamic model is used to design a steel stud wall system to
achieve a desired the level of performance under any explosion threat level. A full-scale
validation experiment demonstrated that the analytical model conservatively predicts the
measured experimental results. This dissertation presents the analytical modeling and
experimental evaluation of steel stud wall systems under blast loads.
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Most construction projects are large and costly. Collaborative working involves two or more stakeholders sharing their efforts and resources to complete the project more effectively and efficiently.
Collaborative, integrative and multi-disciplinary teams can tackle the complex issues involved in creating a viable built environment. This tends to be looked at from three interrelated perspectives: the technological, organizational, and social; and of these the key issue is to improve productivity and enable innovation through the empowerment and motivation of people.
This book provides insights for researchers and practitioners in the building and construction industry as well as graduate students, written by an international group of leading scholars and professionals into the potential use, development and limitations of current collaborative technologies and practices. Material is grouped into the themes of advanced technologies for collaborative working, virtual prototyping in design and construction, building information modelling, managing the collaborative processes, and human issues in collaborative working.
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I need new version of these 2 codes and I would be pleased if you help me.
ASTM C618 - 12 Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete
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ASTM C311 - 11b Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete
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Abstract
We developed a methodology of seismic isolation retrofit integrating adjacent buildings using prestressed concrete slabs, and applied it to two large-scale buildings in Hamamatsu City in Shizuoka Prefecture in Japan. It is the first seismic isolation retrofit of hospital in Japan. The two steel-reinforced concrete buildings were nine stories high with one basement, and had been constructed in 1973 and 1975 based on an old structural design code. The two buildings were integrated into one building by connecting individual floors using post-tensioned prestressing cables through slabs. A comparison of microtremors before and after the integration confirmed that the integration worked well. Seismic isolation devices were set up mainly in basement columns using temporary support involving steel brackets and prestressing cables to install devices safely and economically (Masuzawa et al., 2004 [1]). In the seismic design phase, broadband-generated earthquake ground motions for a hypothetical Magnitude 8 earthquake near the site were simulated using a hybrid method (Hisada, 2000 [2], etc.). Safety and functionality were verified by evaluating structural seismic performance based on time-history seismic response analysis.
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i need the following paper :
Seismic Isolation Retrofit of a Medical Complex by Integrating Two Large-Scale Buildings
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This unique critical appraisal of the work of Foster & Partners offers a number of original revelations about the philosophy and design methods that have generated the designs and reputation of the Foster studio over the past three decades. The author begins with a distinctly personal account of Norman Foster's first steps in the world of architecture and goes on to discuss some key buildings which have become symbols of our time.
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