NO.7 â¢ DECEMBER 2008 - The Hong Kong Polytechnic University

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Technology Transfer and Research Developments 技術轉移與科技發展 Nondestructive Evaluation Methods as Evaluation Tools of the Quality of Reinforced Concrete Structures 無損檢測方法可診斷鋼筋混凝土結構的質量 The ability of a civil engineering and building structure to withstand earthquake is dependent on its structural design and quality control during construction. After the Sichuan earthquake, sub-standard constructions have been accused as a major cause of a large number of structural collapses, especially to schools which led to huge numbers of casualties. The alleged sub-standard constructions included (1) deficiency in steel reinforcement inside the concrete structures, and (2) poor concrete quality. There may be a need to scientifically examine the quality of the building structures after the buildings have been completed. Nondestructive evaluation (NDE) methods can be used to visualizethe internal conditions and assess the quality of large-scale reinforced concrete structures without damaging the already built structures. Amongst the many NDE methods being used in the civil engineering discipline, ground penetrating radar (GPR) and ultrasound pulse velocity (UPV) are the two most effective methods in the case of Sichuan. basic GPR system costs less than US$50,000; while a basic UPV system costs about US$5,000; (5) user friendly: 1-2 day training is adequate for personnel with a civil engineering background, and (6) portable: typically, these systems weigh about a few kilograms which makes mobilization and handling very convenient. 12 Figures 1 GPR reveals the arrangement of steel reinforcements embedded in a concrete wall. Figures 2 The UPV set up GPR transmits high-frequency electromagnetic (EM) wave into the internal concrete structure via a small transmitting antenna placed on the concrete surface. Anomalies (such as steel reinforcement) embedded in the reinforced concrete reflect the EM wave back to the receiving antenna differently from that of the surrounding concrete matrix. Using a portable computer, the measured EM signal can be used to quantify the number and spacing of steel reinforcement present in the concrete in real-time. Figure 1 shows the typical results of such measurements of a reinforced concrete wall. We can clearly seethe internal distribution and alignment of the steel reinforcements (including quantity, spacing and depth) embedded 25mm beneath the concrete surface. The working principle (transmission and reflection) of UPV (Figure 2) is somehow similar to that of GPR, except that its transmission is by sound wave. Transmission of ultrasound in a material is highly correlated with its density, which is a determining factor of the compressive strength of concrete. Hence, this correlation may be used as a rough indicator of the quality of the examined concrete. In general, a concrete with a UPV higher than 3500m/ s may be regarded as a good concrete. The advantages of the above two NDE methods are: (1) reasonably accurate; (2) totally nondestructive to the structure; (3) results are obtained real-time and on-site during the evaluation such that sample collection and associated laboratory tests are not required, typically, a general inspection of a 3-storey building takes about 2 days; (4) relatively inexpensive: a () ( )25 (,) 3,500 ()()() () 5 5,000 () () Professor C.S. Poon 潘智生教授 Email cecspoon@polyu.edu.hk Department of Civil and Structural Engineering 08
Technology Transfer and Research Developments 技術轉移與科技發展 CSE Researchers Conducting Air-quality Study during the Beijing Olympics 土木及結構工程學系人員於奧運期間研究北京市空氣質素 In an attempt to improve the air quality during the Beijing Olympic Games, The Central and Beijing city government implemented drastic measures to reduce the emissions of air pollutants from industries, road traffic, and construction sites. To help assess the effectiveness of these measures and to study their impact on atmospheric chemistry, Civil and Structural Engineering (CSE) researchers led by Prof. Wang Tao, in collaboration with scientists at the Chinese Research Academy of Environmental Sciences and Shandong University, collected comprehensive atmospheric data at three locations in Beijing before and during the Olympics. The data will be used for atmospheric chemistry and climate change studies. The initial results have also been reported to high-level officials at Chinas Ministry of the Environmental Protection to support the assessment of the air quality during the Olympics. This activity has been funded jointly by PolyUs Niche Area Development Scheme, Chinas National Basic Research Program (973 program), and a Research Grant Council – General Research Fund grant. (973 ) Professor Wang Tao 王韜教授 Email cetwang@polyu.edu.hk Department of Civil and Structural Engineering Advanced instruments for measuring a wide range of atmospheric pollutants Prof. Wang (first from the left) and some members of the study team at a field site in Beijing Odour Survey at the Olympic Stables of the 2008 Olympic Equestrian Event 2008 奧運馬術賽馬厩氣味調查 Prof. X. Z. Li 李湘中教授 Email cexzli@polyu.edu.hk Department of Civil and Structural Engineering Requested by Ove Arup & Partners Hong Kong Ltd. the Odour Research Laboratory in Civil and Structural Engineering (CSE) led by Prof. X. Z. Li recently conducted a twoday odour patrol survey at the Olympic stables for the 2008 Olympic Equestrian events. The objective of this was to ascertain that the new stable area would not cause any odour nuisance to the surrounding environment. The odour patrol exercise was conducted on the 4th and 5th of August 2008 just before the Olympic 2008 equestrian event in Hong Kong. Odour patrol in front of Hong Kong Olympic Equestrian venue (Shatin) Odour patrol in competition arena 2008845( ) Odour patrol beside the horse stable Odour patrol at the opposite side of Shing Mun River 09
Page 1 and 2: NO.7 • DECEMBER 2008
Page 3 and 4: Special Feature 專題介紹 The
Page 5 and 6: Special Feature 專題介紹 Now
Page 7 and 8: Special Feature 專題介紹 2)
Page 9: Technology Transfer and Research De
Page 13 and 14: Technology Transfer and Research De
Page 15 and 16: Awards and Achievements 學者學
Page 17 and 18: Awards and Achievements 學者學
Page 19 and 20: Recent Events 活動剪影 Recen
Page 21 and 22: Recent Events 活動剪影 BRE S
Page 23 and 24: Recent Events 活動剪影 34th
Page 25 and 26: Recent Events 活動剪影 BRE S
Page 27 and 28: New Academic Staff 學院新教

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NO.7 â¢ DECEMBER 2008 - The Hong Kong Polytechnic University