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Dive into the research topics where Takaaki Ohkubo is active.

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Featured researches published by Takaaki Ohkubo.


Journal of Structural and Construction Engineering (transactions of Aij) | 2011

A STUDY ON THE INVESTIGATION FOR CHOOSING THE CRACK REPAIR METHOD BASED ON ACTUAL MOVEMENTS OF CRACKS OCCURRED IN THE BUILDING WALLS

Takaaki Ohkubo; Naoyuki Morihama; Yasuhiro Ryuuda; Takuya Hasegawa; Satoshi Fujimoto

This research aims at rationalization of the selecting technique of a crack repair method of construction with the movement occurred in RC structure. The definition of“existence of crack width behavior”of the flow chart in the public organizations specifications for crack repair method selection is so ambiguous. In this research, behavior of the crack produced in the outer wall of an actual building was measured, and new knowledge was able to be acquired about the opening-and-closing pattern and crack width behavior of cracks which were produced in the outer wall of building. Although it was generated in the building of only one building, and the cracks and consideration in this paper are based on this measurement results, it was thought that the results of this paper has the flexibility about the crack investigation for selection of a repair method of construction.


Advanced Materials Research | 2011

Concrete Mix Design Incorporating Additional Consideration of Environmental Performance

Zhuguo Li; Takaaki Ohkubo

In this paper, we gave a clear concept of environmental performance (EP), and proposed an estimating method of environmental performance indicator (EPI) for concrete, based on an integrated life cycle impact assessment. The environmental burden (EB) factors of concrete were also discussed. In order to well evaluate the environmental benefits of waste utilization, land use change and nature environmental resource loss caused in the production stage of concrete were also taken as the EB factors and their estimating methods were given, besides air emissions, waterborne releases, and exhaustible resource consumption. Furthermore, An EB intensity database was constructed for concrete’s raw materials and processes such as transportation. An environment-conscious mix design method was suggested for maximizing EP of concrete, while still meeting the usual property requirements such as consistency, strength and durability. Finally, as an application example, mix proportions of a retaining wall concrete were designed.


Journal of Structural and Construction Engineering (transactions of Aij) | 2010

CRACK PREDICTION ANALYSIS FOR DRYING SHRINKAGE OF WET FINISHING PLASTERING MATERIALS ON THE EXTERNAL WALL

Shinya Matsumoto; Takaaki Ohkubo

In this paper, it is shown that a crack prediction analysis for drying shrinkage of wet finishing plastering materials on the external wall. In this analysis, the drying shrinkage strain in the mortar is determined by proposal measurement procedure for the age. The internal stress in the finishing mortar is analyzed by finite element method based on the plane stress problem for the drying shrinkage strain derived from experimental measurement. We illustrate the method which predicts the crack generation point and time in finishing mortar. This present method is formulated by two-dimensional finite element method to apply the crack prediction for the opening on wall corners. The effectiveness of present method is verified by comparing the numerical results with the experimental tests. We investigate analytically the typical characteristics of the drying shrinkage of the external wall using wet finishing plastering material by numerical studies.


Journal of Materials in Civil Engineering | 2004

Theoretical Analysis of Time-Dependence and Thixotropy of Fluidity for High Fluidity Concrete

Zhuguo Li; Takaaki Ohkubo; Yasuo Tanigawa


Journal of Materials in Civil Engineering | 2004

Yield Model of High Fluidity Concrete in Fresh State

Zhuguo Li; Takaaki Ohkubo; Yasuo Tanigawa


Journal of Materials in Civil Engineering | 2004

Flow performance of high-fluidity concrete

Zhuguo Li; Takaaki Ohkubo; Yasuo Tanigawa


Aij Journal of Technology and Design | 2009

COMMUNICATION PERFORMANCE OF IC-TAGS INSTALLED INSIDE CONCRETE

Hisashi Sugiyama; Takaaki Ohkubo; Shiro Nakajima


Aij Journal of Technology and Design | 2011

COMMUNICATION PERFORMANCE OF IC-TAGS INSTALLED INSIDE LARGE-SIZE CONCRETE SPECIMENS

Hisashi Sugiyama; Hideaki Sumikura; Takaaki Ohkubo; Junko Koga; Tsutomu Hirade


Journal of Structural and Construction Engineering (transactions of Aij) | 2003

THEORETICAL INVESTIGATION ON SHEAR FLOW OF HIGH FLUIDITY CONCRETE

Zhuguo Li; Takaaki Ohkubo; Yasuo Tanigawa; Hiroshi Mori


Journal of Structural and Construction Engineering (transactions of Aij) | 2001

STUDY ON LIMIT STRESS AT SHEAR FAILURE OF FRESH MORTAR BY MICROSCOPIC APPROACH

Zhuguo Li; Yasuo Tanigawa; Hiroshi Mori; Takaaki Ohkubo

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Kei-ichi Imamoto

Tokyo University of Science

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