This paper reports on an investigation conducted on existing bridges in Vietnam. The evaluation approach includes visual inspections and non-destructive tests of concrete structures, personal interviews of site engineers in the field and reviews of available publications from the media and literature. The diagnostics confirm that the concrete is of low quality and shows many shortcomings, such as failure, damage, local defects and premature ageing. A series of diversified maintenance strategies is proposed to focus on both tactical and strategic levels. It is necessary to rectify current problems of concrete structures, to prevent such a collapse in future, and to enhance physical and serviceable conditions of existing bridges in Vietnam.
This paper is concentrated on investigating the modern methods to evaluate the probability of cracking in urban tunnel structures during construction. The study considers the current standard methods for assessing reinforced concrete walls of an urban tunnel, which experienced early-age cracking. The results obtained using guidelines were compared with actual observations of crack widths in the urban tunnel wall. Examples of using specifications in wall design were also described. The proper method is highlighted with suggestions for a possible path for considering early-age thermal and shrinkage effects in urban reinforced concrete tunnel walls
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