J-Stage (Journal of JSCE in Engish)
J-Stage (Journal of JSCE (E2 Division) in Japanese)

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STUDY ON BEARING CAPACITY OF AIRPORT PAVEMENT DAMAGED DUE TO THE 2011 TOHOKU REGION PACIFIC COAST EARTHQUAKE

Yukitomo TSUBOKAWA, Naoya KAWAMURA, Junichi MIZUKAMI, Ryota MAEKAWA
Vol. 5, No. 1, p.58-67, Journal of JSCE (in English)

Abstract:
The 2011 Tohoku Region Pacific Coast Earthquake struck off Tohoku and Kanto regions of Japan on 11 March 2011. We conducted investigations of structural and surface damage to pavement in the runway, taxiway and apron at Sendai Airport for the purpose of re-opening the airport for commercial flights. Many cracks were confirmed in the asphalt pavement in the runway and taxiway. However, it was clarified that these cracks except the one in the taxiway were not fatal structural damage that would hinder the provisional use of the airport. Large settlement was confirmed in a part of the asphalt pavement in the taxiway and concrete pavement in the apron due to liquefaction. It was confirmed that these settlement areas needed to be reconstructed for the re-opening of the airport. Furthermore, the effect of the void underneath the cement concrete slab on FWD deflection was clarified.

EVALUATION FOR ASR DETERIORATIONS BASED ON ANALYSES OF STIRRUP DAMAGE AND INTERNAL CRACKING OF CONCRETE

Nobuo UEHARA, Kenji KOSA, Hiro taka MASUDA and Yuji UEZONO
Vol. 73, No. 1, p.1-15, Journal of JSCE (Division E2) (in Japanese)

Abstract:
For investigating correlations among external and internal cracking of concrete as well as the stirrup damage caused by ASR deterioration, several specimens arranged by main reinforcement and stirrup are exposed under outdoor environment. The detailed observation and evaluation are performed for speci- mens with severe deterioration degree. As a result, it is noted that cracking in external concrete is perpen- dicular to surface and stagnate at the depth of stirrup; while, the internal cracking has the trend to generate with various direction and short length due to the constr aint from stirrup. Further, it is considered that the stirrup confinement is effective when suffering dete rioration without stirrup rupture; however, under the circumstance where stirrup rupture occurs, external cracking has the possibility to extend through the deeper position around the rupture location of stirrup, accompanied by acutely increasing width and dif- ferences in level on the surface.

EVALUATION OF AIR-VOID SYSTEM S IN CONCRETE BY POINT PROCESS STATISTICS AND ESTIMATION OF THE CONVENTIONAL SPACING FACTOR

Takuma MUROTANI, Hidefumi K OTO and Shin-ichi IGARASHI
Vol. 73, No. 1, p.36-49, Journal of JSCE (Division E2) (in Japanese)

Abstract:
Distribution of air voids in concrete was regarded as 2D spatia l point processes. Characteristics of their distribution were evaluated by several spatial statistics functions. Furthermore, a characteristic distance between air voids was defined in the nearest neighbor distance function. Correspondence between the char- acteristic distance and the conve ntional spacing factor was inv estigated. Clustered distribution of air voids due to the presence of aggregate particles were properly estima ted by the spatial statistics functions. How- ever, as far as the cement paste matrix was concerned, it was p ossible to assume that air voids were distrib- uted randomly except a range of short distances. Thus, spatial structure of air-void systems, in particular the characteristic distance between air voids could be simply simulated as a random point process. Further- more, the characteristic distance of real air-void distribution was almost the same as the conventional spac- ing factor. Compared to the co nventional spacing factor that is obtained by following the ASTM C457 procedure, the characteristic dis tance is quite easy to obtain. Furthermore, taking account of the fact that the characteristic distances measured for real distribution in concretes are plotted within the 95% confidence interval of binominal random point process, air-void systems in concrete can be assumed as 2D Poisson point process. Thus, a simple equation to obtain the spacing fa ctor from a point process was proposed. The spacing factor was correctly est imated by the equation. Therefo re, the characteristic distance of air voids defined in this study can be used as a new distance parameter b etween air voids, alternatively it may be used as a parameter to estimate the traditional spacing factor.

16-YEARS STUDY REPORT ON CONSTRUCTION AND PERFORMANCE EVALUATION OF PRESTRESSED CONCRETE BRIDGE WITH HIGH DURABILITY TO SALT DAMAGE
(Report)

Toshiyasu TOYOFUKU, Norio KAMIYAMA, Satoshi UEZU, Kazuyuki TANAKA, Junqing XIN, Yoshitaka MAEDA and Keita FUKUCHI
Vol. 73, No. 1, p.16-35, Journal of JSCE (Division E2) (in Japanese)

Abstract:
Yakabi Bridge was the first highly durable PC road bridge in Japan constructed for minimum maintenance (corrosion protection by multiple means), through the use of concrete containing ground granulated blast furnace slag #6000, prestressing steel strand with individually coated wires, epoxy resin coated reinforcing bar, plastic duct for the ducts, waterproof construction on the bridge surface, aluminum parapet rail for the parapets, and rubber bearing for the bearings. This paper summarizes the results of the research activities carried out through academic-industrial-government cooperation into the construction of a PC structure with high durability against salt damage over a period of 16 years that included a program of follow-up tests on the actual bridge and additional tests on exposed test specimens in order to verify the e ff ect of these measures against salt damage. The analysis verified that construction method of high durability PC road bridge using these materials was very e ff ective as a measure against salt attack.