Analytical Results and Summary

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The analytical shear stress-shear strain relationships are shown in Figs. 5.35- 5.37. The ultimate shear strengths are shown in Table 5.7. From Fig. 5.35, it

ra u a.

2 £ lo 0)

/

f' / /

r

T^^wmm

\S

0.005 0.010 Shear Strain

0.015

Fig. 5.35. Analytical results of a series with variation of combination of pt and say.

2

* . . . , • • i 1 1 t i • — " y ft

ir

it h

/ ^

-05 o a

- 0 . 3 <rB

,.-'••-

-^r.

\~/r

- 0

0.005 0.010 Shear Strain

0.015

Fig. 5.34. Analytical results of a series with variation of axial stress ratios.

<o u 0-

5 55

01

f

/ f

—.,— ^

1 / / s"

1 /'

"if:CL

'r-OSa, j

, ' - ^ " s j . . -

. . . . - • "

0

0.005 0.010 0.015 Shear Strain

Fig. 5.37. Analytical results of a series with variation of bidirectional axial stress ratios.

Table 5.7. Specimens and maximum strength.

t t

<

•4-t— 1 I

~v I t

<*— 1

A ^ r

4—

Specimen a-1 a-2 a-3 b-1 b-2 b-3 b-4 c-1 c-2 c-3 c-4

SD980,p, = 2.0%

SD490,/7, = 4.0%

SD295,p, = 6.6%

Axial force, none Axial force, 0.1 oB

Axial force, 0.3 Ofl

Axial force, 0.6 o8

Axial force, none Axial force, 0.1 aB

Axial force, 0.3 ofl

Axial force, 0.6 o"B

Max. Strength MPa 15.14 17.94 19.34 15.14 16.17 18.11 19.87 15.14 17.48 24.17 33.87

is indicated t h a t t h e stiffness after cracking a n d t h e u l t i m a t e shear s t r e n g t h increased according t o t h e increase of reinforcement r a t i o , pt, even when pt x

soy (s<Ty'- yielding s t r e n g t h of t h e reinforcement) was kept c o n s t a n t . F r o m Figs. 5.36 a n d 5.37, it is seen t h a t t h e axial compressive stresses, uniaxial or biaxial, c o n t r i b u t e d t o t h e increase of cracking s t r e n g t h a n d u l t i m a t e shear s t r e n g t h . T h e effect was m o r e remarkable for biaxial compressive stresses t h a n uniaxial compressive stress.

R e f e r e n c e s

5.1. Washizu, K. ed., Finite Element Method Handbook, Part 1: Basic Edition, Baifukan, September 1981, p. 443 (in Japanese).

5.2. Togawa, H., Introduction of Finite Element Method, Series 1 of Basic and Application of FEM, Baifukan, November 1981, p. 324 (in Japanese).

5.3. Zienkiewicz, O.C., The Finite Element Method, Third Edition, McGraw Hill Book Company Ltd., 1977.

5.4. Miyoshi, T, Introduction to FEM, Revised Edition, Baifukan, December 1994, p. 255 (in Japanese).

5.5. Ngo, D. and Scordelis, A.C., Finite element analysis of reinforced concrete beams, ACI J. 64(3), March 1967, pp. 152-163.

5.6. IABSE, Advanced mechanics of reinforced concrete, Reports of IABSE Colloquium, No. Delft, 1981.

5.7. Research committee on shear strength of RC structures, Reports of JCI Colloquium on Analytical Studies on Shear Problems of RC Structures, Japan Concrete Institute, JCI-C1, June 1982 (in Japanese).

5.8. Morita, S. (Representative Researcher), Basic test and development of analytical models necessary for development of prediction accuracy of F E M analysis of RC structures, Research Reports of the Grant-in-Aid, the Ministry of Education, March 1989 (in Japanese).

5.9. Finite element analysis of reinforced concrete structures, Proc. US-Japan Seminar, Tokyo, May 1985, published from ASCE, 1986.

5.10. Aoyama, H. and Noguchi, H., Future prospects for finite element analysis of reinforced concrete structures, Proc. US-Japan Seminar, Tokyo, May 1985, published from ASCE, 1986, pp. 667-681.

5.11. Research committee on F E M analysis and design method of R C structures, Guideline on the Application of FEM to Design of Concrete Structures, Japan Concrete Institute, JCI-C16, March 1989 (in Japanese).

5.12. Research committee on F E M analysis and design method of RC structures, Reports of the Analytical Studies on Macroscopic Models and FEM Micros- copic Models of RC Shear Walls, Japan Concrete Institute, JCI-18, 1989 (in Japanese).

5.13. Finite element analysis of reinforced concrete structures II, Proc. Int.

Workshop, New York, June 1991, published from ASCE, 1993.

5.14. Naganuma, K., Analytical model of concrete structures, FEM analysis as a design method of concrete structures, Part 4, Concrete J. 30(8), 1992 (in Japanese), pp. 81-86.

5.15. Shirai, N., Concrete structures and FEM analysis, F E M analysis as a design method of concrete structures, Part 3, Concrete J. 30(6), 1992, pp. 86-93 (in Japanese).

5.16. Stevens, N.J. et al., Analytical Modeling of Reinforced Concrete Subjected to Monotonic and Reversed Loadings, Pub. No. 87-1, University of Toronto, January 1987.

5.17. Constitutive equations and FEM WG in the sub-committee on high strength reinforcement, Research Reports, Kokudo Kaihatsu Technical Research Center, March 1993, p. 207 (in Japanese).

5.18. Suzuki, N., Guideline for nonlinear F E M analysis of RC structures, Parts 1 and 2, FEM analysis as a design method of concrete structures, Concrete J.

31(8), 1993, pp. 78-83; 31(9), 1993, pp. 76-81 (in Japanese).

5.19. Structural performance sub-committee in the New RC project, Research Reports, Kokudo Kaihatsu Technical Research Center, March 1992 (in Japanese).

5.20. Research committee on shear strength of RC structures, Reports of the 2nd JCI Colloquium on Analytical Studies on Shear Problems of RC Structures, Test Data of the Specimens for Verification of Analytical Models, Japan Concrete Institute, JCI-C6, October 1983, p. 54 (in Japanese).

5.21. Fafitis, A. and Shah, S.P., Lateral reinforcement for high strength concrete columns, ACI J. 1985, pp. 213-232.

5.22. Ohkubo, M., Hamada, S. and Noguchi, H., Basic test on compressive deterioration characteristics of cracked concrete under seismic loading, Proc.

JCI Colloquium, JCI-C18, October 1992, pp. 17-22 (in Japanese).

5.23. Summary reports on New RC research projects, Kokudo Kaihatsu Technical Research Center, March 1992 (in Japanese).

5.24. Sakino, K., Mechanical Characteristics of confined concrete, Research Reports of Sub-Committee on High Strength Reinforcement, Kokudo Kaihatsu Technical Research Center, March 1992 (in Japanese).

5.25. Ohkubo, M., Matsudo, M. and Noguchi, H., Experimental study on failure criterion of ultrahigh strength concrete under biaxial compressive stresses, Proc. AIJ Ann. Convention, Structure 2, October 1990, pp. 635-638, and September 1991, pp. 473-476 (in Japanese).

5.26. Noguchi, H. and Zhang, A., Analytical study on the effects of axial force on the shear strength of RC columns, Proc. JCI 13(2), 1991, pp. 381-384 (in Japanese).

5.27. Ihzuka, T., Study on Constitutive equations and F E M analysis of reinforced concrete using from ordinary to high strength materials, Doctoral Thesis of Chiba University, 1992 (in Japanese).

5.28. Amemiya, A., Experimental study on shear behavior of ultrahigh strength beams, Proc. AIJ Ann. Convention, Structure 2, October 1991 (in Japanese).

5.29. Architectural Institute of Japan, Design guideline for earthquake resistant reinforced concrete buildings based on ultimate strength concept, 1990, p. 340 (in Japanese).

5.30. Ichinose, T., Shear design method of reinforced concrete members considering deformation capacity, Trans. AIJ, 1990 (in Japanese).

5.31. Comite Euro-International Du Beton, CEB-FIP model code for concrete struc- tures, 1988.

5.32. Kent, D.C. and Park, R., Flexural members with confined concrete, Proc.

ASCE 97(ST7), 1971, pp. 1969-1990.

5.33. Park, R., Priestly, M.J.N, and Gill W.D., Ductility of square confined concrete columns, Proc. ASCE 108(ST4), April 1982.

5.34. Nimura, A., Seo, M. and Noguchi, H., Study on behavior of reinforced concrete columns using high strength materials, Proc. AIJ Ann. Convention, Structure 2, August 1992, pp. 627-630 (in Japanese).

5.35. Zhang, A., Nonlinear analysis of shear behavior of reinforced concrete members, Doctoral Thesis of Chiba University, 1991 (in Japanese).

5.36. Abe, M., Takezaki, S. and Noguchi, H., Study on development of high strength reinforcement, Parts 10 and 11, Proc. AIJ Ann. Convention, Structure 2, 1992, pp. 513-516 (in Japanese).

5.37. Shirai, N., Noguchi, H. and Shiohara, H., Study on constitutive laws of reinforced concrete element using ordinary and high strength materials, Parts 1 and 2, Proc. AIJ Ann. Convention, Structure 2, August 1992, pp. 1051-1054.

5.38. Kabeyasawa, T. et al., Restoring force characteristics of reinforced concrete shear walls with the flexural yielding using high strength materials, Parts 1 and 2, Proc. AIJ Ann. Convention, Structure 2, October 1990, pp. 607-610.

5.39. Kabeyasawa, T. and Kuramaoto, H. et al., Loading test of high strength reinforced concrete shear walls with large shear span ratios, Trans. JCI Ann.

Convention 14(2), 1992, pp. 819-824 (in Japanese).

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5.41. Shohara, R., Shirai, N. and Noguchi, H., Comparisons of macroscopic models of reinforced concrete shear walls with test results, Reports of Panel Discus- sion on Macroscopic Models and FEM Microscopic Models of RC Shear Walls, JCI-C11, JCI, January 1988, pp. 41-60 and 97-102 (in Japanese).

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Structural Design Principles

Masaomi Teshigawara

Head, Structure Division, Department of Structural Engineering, Building Research Institute, Ministry of Land, Infrastructure and Transport,

1 Tachihara, Tsukuba, Ibaraki 305-0802, Japan E-mail: teshi@kenken.go.jp

The Structural Design Committee of the New RC research project compiled as its outcome "the structural design guideline for New RC buildings". In this chapter, basic ideas and principles of this design guideline will be explained.

Although the title of this chapter refers to the structural design in general, this chapter is entirely devoted to the seismic design. This limited scope is due to the following two reasons. First, the New RC research project, on the results of which this book is based, is concentrated on the seismic behavior and seismic design of RC structures with high strength materials. Secondly, it is usually regarded that the use of high strength concrete and steel does not necessarily improve the behavior under vertical loading, except, at most, for possible reduction of elastic deflection. The use of high strength materials in the vertical load design does not warrant a merit.

As far as seismic design is concerned, it is possible and necessary to take full advantage of high strength. For RC buildings with ordinary strength materials, the recent trend of seismic design, particularly of lowrise to medium- rise buildings, is to assume weak-beam strong-column type collapse mechanism.

Highrise buildings, on the other hand, tend to receive significant influence of higher modes, and many beams do not necessarily yield within the design seis- mic deformation limit. Design forces are calculated, not based on the assumed mechanism, but based on the earthquake response analysis.

271

The use of high strength material, particularly that of high strength steel, amplifies this trend. The yield deflection of members with such mate- rial becomes larger, about twice as much as that of ordinary material. Highrise buildings with high strength members would not produce much beam yield hinges within the design seismic deformation limit. In this situation the design based on the collapse mechanism is not realistic, and it is mandatory to use earthquake response analysis for the design. Hence a completely new seismic design method was developed for New RC structures.

This chapter explains background and characteristics of this design method in the following order. Section 6.1 introduces the main features of the proposed design method. Section 6.2 is on the seismic design criteria in three stages.

Section 6.3 features simulated earthquake motions specifically developed for new RC structures. Sections 6.4 and 6.5 discuss the modeling of structures for response analysis and restoring force characteristics of structural members.

Section 6.6 again discusses the earthquake motions, particularly on the effect of bidirectional horizontal motions and that of vertical motions. Section 6.7 is devoted to foundation design, and the last, Sec. 6.8 introduces several buildings ranging from 15 to 60 stories designed in detail using New RC material.

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