Concrete filled tubular column with ultra high strength materials

Taisei Corporation – Japan

Concrete filled tubular column with ultra high strength materials

Building use

Office building

Country/Region

Japan

Overview

In recent super high-rise buildings, there are many cases where large spans are required to gain spacial freedom on typical floors and wide atria to allow continuity with the external spaces on the lower floors. In order to achieve these spaces, it is necessary to provide high strength in the structural members that constitute the building structure, particularly the columns. It is possible to avoid excessively large volume columns by using appropriate combinations of high strength materials. Therefore ultra high strength concrete filled tubular (CFT) columns that combine ultra high strength concrete and ultra high strength steel material have been developed.

Basic information (construction date, number of stories, gross floor area, adopted design code, engineer(s), Contractor(s), etc.)

Construction date: 2014
Number of stories: 38
Gross floor area: 198,000m2
Adopted design code: Japan Building Standard act, Design procedure for Steel Building with Concrete Filled Steel Tubular Structures, Time-history response analysis
Engineer(s): Taisei Corporation
Contractor(s): Taisei Corporation

Issue and/or innovation

To actually apply these high strength materials to CFT columns, the following issues regarding construction and production aspects had to be addressed.
– Confirm the structural performance in order to verify the validity of the load resistance evaluation equations for the strength of CFT columns using the combination of the ultra high strength materials.
– Fc150N/mm2 class ultra high strength concrete contains more binder material in the ingredients, mainly cement, so when the concrete is fresh, viscosity is high. Therefore pump delivery technology that is capable of supplying concrete stably with high pressure is necessary in order to reliably pour the concrete into the steel tubes.
– In order to fill steel tubes with Fc150N/mm 2 class ultra high strength concrete, blending technology that minimizes shrinkage when the concrete has hardened is necessary.
– In order to use high strength steel materials, it is necessary to select the welding materials and the various conditions (location of welding works, temperature, weld location, welding equipment, welding method) in accordance with special welding control methods.

Reason for composite solution

Normally CFT columns are column members with excellent structural performance that utilize the characteristics of concrete, which is strong in compression, and steel, which are strong in bending (tension), so they are adopted in high-rise buildings. However, when conventional materials are used, the dimensions of the column cross-section are excessive on the lower stories when designing 200 to 300m class super high-rise buildings having long spans. Also when a mega structure is adopted in which multiple members are combined together, the volume of the structure is too large, which excessively affects the core planning and the façade design, so there is a possibility that the intended building design cannot be finalized. Therefore, ultra high strength CFT columns have been developed with the aim of providing members that can satisfy the architectural planning and sufficiently satisfy seismic safety with a volume of column members similar to those of medium-rise buildings. These columns combine ultra high strength concrete with specified strength of Fc150N/mm2 and ultra high strength steel with a tensile strength of 780N/mm2, and they have been adopted on this building.

Technical details

In this R&D, structural experiments were carried out to clarify the compressive performance and structural performance of ultra high strength CFT columns under seismic loading. The ultimate strength of ultra high strength CFT was verified by a calculation based on superposed strength with using the revised factor for the strength of concrete considering the adaptability of strain between the steel and the concrete, and the stress distribution of concrete. Fc150N/mm2 concrete is raised to the top of the column under pressure from the pump vehicle. Various items were confirmed such as the stability when pumping the concrete, changes in the properties of the filling concrete, condition of the concrete after hardening, strength distribution, etc., and it was confirmed that construction can be reliably carried out. The welding was carried out in the horizontal attitude at the actual site. The results of these tests confirmed the combination of steel material and weld material, the weld performance, and weld constructability.

Specific solution/technical details

This building will be constructed in Tokyo and will consist of offices, commercial facilities, a parking lot, etc., and will have a hotel on the upper floors. The building will have 6 floors underground and 38 floors above ground, approximately 200m in height, and a total floor area of approximately 198,000m2. The plan is approximately 97m long with 14 spans of 7.2m each, and approximately 47m long with 3 spans including a 22m span.
A total of ten ultra high strength CFT columns that combined 780N/mm2 steel and Fc150N/mm2 concrete were used in the building: six columns on the south face of the building spanning 14.4 m from the basement second story to the third story above ground, and four corner columns on 1F in the center of the building supporting 22m floors above ground in both north and south directions.

Impact or effectiveness

In the low-rise part of this building, as an underground plaza for station strengthening of adjacent subway station of 5 stations, a comfortable continuous integrated space was required through the atrium. By adopting the ultra high strength CFT columns, a wide large space with few columns was realized in the lower floor of the super high-rise buildings with heavy structural burden. Specifically, as a super high-rise building, columns arranged in a span of 7.2 m in the girder direction could be consolidated to 14.4 m, and it became possible to secure a large space with plenty of space in the lower level which is most important in the building plan. By using these columns, the following can be expected:
1) Achieving a slim frame and a highly flexible building space
2) Supporting building weight with a small column section and a small number of columns
3) Maintaining No-damage (elastic) until large deformation during a large earthquake
4) Reduction in steel volume compared to conventional steel
5) Rationalization of manufacturing, transportation, and on-site construction of materials

References / Technical Papers Content

S. Matsumoto, T. Komuro, H. Narihara, S. Kawamoto, O. Hosozawa and K. Morita : Structural Design of an Ultra High-rise Building Using Concrete Filled Tubular Column with Ultra High Strength Materials, 15th World Conference on Earthquake Engineering (15 WCEE), Lisbon, Portugal, 2012
Sato, E., Matsumoto, S., Narihara, H., Komuro, T. and Yasuda, S. (2009). Structural Performance of CFT Column Using Super High Strength Materials (Part1-2). Summaries of Technical Papers of Annual Meeting, Architectural Institute of Japan, Structure Ⅲ, pp.1217-1220. (in Japanese)
Morita, K., Keii, M. and Matsumoto, S. (2011). Applications of high performance structural steels to high-rise steel buildings. The 6th International Symposium on STEEL STRUCTURE (ISSS-2011), International Journal of Steel Structure, pp.21-35.
Narihara, H., Kobayashi, M., Matsumoto, S., Inaba, Y., Goto, K. and Fujisawa, S. (2010). Welding Procedure Test on Build up Box Column Made of 780N/mm2 Class Tensile Strength Steel for Building Structure (Part1-2). Summaries of Technical Papers of Annual Meeting, Architectural Institute of Japan, Material and Construction, pp.1123-1126. (in Japanese)
Goto, K., Kuroiwa, S., Matsumoto, S., Kawamoto, S., Tsujiya, K., Nakamura, T. and Yagi, K. (2011). Experimental Study on Construction with CFT Column using Fc150N/mm2 Concrete by Actual Size Models. Summaries of Technical Papers of Annual Meeting, Architectural Institute of Japan, Material and Construction, pp.333-334. (in Japanese)