| Author | Sarayoot Thongyot |
| Call Number | AIT Thesis no.ST-00-4 |
| Subject(s) | Concrete construction--Deterioration
Offshore structures
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of
Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | Reinforced concrete has been used widely in the marine environment during this
century. The concrete has excellent durability and provides a satisfactory level of protection of
the steel embedded inside. However, marine environment is very aggressive condition so that
corrosion of the steel reinforcement cannot be avoided. Therefore, the proper rehabilitation
methods should be applied to repair the structures. But the problem is how to select the
suitable rehabilitation methods. The purpose of this research is development of the system to
select rehabilitation methods. Firstly, the degradation curves of structural performances are
evaluated. Three performances that are load bearing capacity, safety perception for third
parties and aesthetics performance are considered. The load bearing capacity is evaluated
theoretically, while safety perception for third parties and aesthetics performance are evaluated
from the results obtained by online questionnaire. Furthermore, the selection of rehabilitation
methods is also gathered from the opinion of the skillful engineers how to repair the structures
by using online questionnaire also.
The results show that load bearing capacity is degraded with time due to chloride attack.
The degradation rate of load bearing capacity depends on many factors such as cover
thickness, reinforcement diameter and reinforcing arrangement. Degradation rate will be large
if using small size of diameter, and the corrosion will start very soon if using small cover
thickness. Therefore, large diameter of steel with enough concrete cover is suggested. It is
clearly shown that the change of failure mode from flexural mode to shear mode can occur in
corrosion process if much larger corrosion amount occurs on shear reinforcement compared
with flexural reinforcement. Degradation in safety perception for third parties and aesthetics
performance will be different when the structures is deteriorated from different sources. The
aesthetics performance is degraded largely in case of color changing when compared with
safety perception for third parties. However, they are degraded closely in case of cracking and
spalling. Both performances are rapidly degraded in case of spalling and degradation level is
very high. The repair is strongly needed to recover both performances when the spalling
occurs. The need of repair action is decreased respectively in case of cracking and color
changing.
The engineers require only coating to recover the aesthetics performance when the
structures are deteriorated from color changing. For cracking, the crackfilling with coating is
mostly required as rehabilitation methods. In addition, the strengthening is also preferred in
repairing of large cracks. For spalling, the crackfilling, coating, patching and electrochemical
methods are suggested to use. Especially, the electrochemical are noticeably suggested in the
repair of spalling. The cyclic repair is required increasingly to repair the structures deteriorated
from color changing, cracking and spatting respectively. |
| Year | 2000 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Takewaka, Koji; |
| Examination Committee(s) | Nii, Kazuyoshi ;Worsak Kanok-Nukulchai; |
| Scholarship Donor(s) | Asian Institute of Technology (Partial Scholarship) |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2000 |
