Developments in the seismic design of reinforced concrete frames in New Zealand

1981 ◽  
Vol 8 (2) ◽  
pp. 91-113 ◽  
Author(s):  
T. Paulay
Keyword(s):  
Reinforced Concrete ◽  
New Zealand ◽  
Experimental Studies ◽  
Design Procedure ◽  
Capacity Design ◽  
Concrete Frames ◽  
Plastic Hinges ◽  
Reinforced Concrete Frames ◽  
Code Of Practice ◽  
Recent Developments

A review of recent developments in the formulation of a design approach for ductile earthquake resisting reinforced concrete frames is presented. In particular the concepts of a deterministic design procedure, termed "capacity design," the advantages of moment redistribution, and the effects of gravity load dominance are discussed. In capacity design (a detailed definition of the term is given in Sect. 2.1) the designer attempts to enforce the development of a unique and desirable pattern of plastic hinges when these are required to dissipate significant amounts of energy to ensure the necessary hysteretic damping. The application of a capacity design procedure in determining the design actions for columns of multistorey frames is examined. Some issues relevant to instability during the inelastic dynamic response of frames are also discussed. Using recent experimental evidence, the inelastic behaviour of reinforced concrete columns, shear effects on potential plastic hinges, and special features of the behaviour of beam–column joints, when these are subjected to severe earthquake simulating reversed cyclic loading, are briefly described. Conclusions drawn from these recent experimental studies, which are being considered for incorporation into the new New Zealand concrete design code of practice, are also reported.

Effects of strain-ageing on New Zealand reinforcing steel bars

2009 ◽  
Vol 42 (3) ◽  
pp. 179-186 ◽  
Author(s):  
A. Momtahan ◽  
R.P. Dhakal ◽  
A. Rieder
Keyword(s):  
Reinforced Concrete ◽  
New Zealand ◽  
Yield Strength ◽  
Seismic Design ◽  
Reinforcing Steel ◽  
Reinforcing Bars ◽  
Capacity Design ◽  
Plastic Hinges ◽  
Strain Ageing ◽  
Steel Bars

Modern seismic design codes, which are based on capacity design concepts, allow formation of plastic hinges in specified locations of a structure. This requires reliable estimation of strength of different components so that the desired hierarchy of strength of the structural components can be ensured to guarantee the formation of plastic hinges in the ductile elements. As strength of longitudinal reinforcing bars governs the strength of reinforced concrete members, strain-ageing, which has significant effect on the strength of reinforcing bars, should be given due consideration in capacity design. Strain-ageing can increase the yield strength of reinforcing steel bars and hence the strength of previously formed plastic hinges, thereby likely to force an unfavourable mechanism (such as strong beam-weak column leading to column hinging) to take place in subsequent earthquakes. In this paper, the strain-ageing effect of commonly used New Zealand reinforcing steel bars is experimentally investigated. Common New Zealand steel reinforcing bars are tested for different levels of pre-strain and different time intervals up to 50 days, and the results are discussed focussing on the extent of strain-ageing and its possible implications on seismic design provisions. The results indicate that designers need to use a higher flexural strength (in addition to overstrength) for the weaker member in checking the strength hierarchy in capacity design of reinforced concrete frames. Similarly, in designing retrofit measures to restore a damaged reinforced concrete member engineers need to take into account an increase of yield strength of the reinforcing steel bars employed in the member due to the strain-ageing phenomenon and the extent of increase in the yield strength depends on the level of damage.

scholarly journals Capacity design of reinforced concrete frames for ductile earthquake performance

1972 ◽  
Vol 5 (4) ◽  
pp. 133-142
Author(s):  
I. C. Armstrong
Keyword(s):  
Reinforced Concrete ◽  
Design Criteria ◽  
Capacity Design ◽  
Concrete Frames ◽  
Reinforced Concrete Frames ◽  
Earthquake Performance

The basis of the design of reinforced concrete frames for fully ductile earthquake performance, applicable to low buildings as well as to major structures, is outlined in terms of capacity design criteria now considered essential to prevent non-ductile failures and enable the building to survive earthquake attack.

scholarly journals Developments in the design of ductile reinforced concrete frames

1979 ◽  
Vol 12 (1) ◽  
pp. 35-48 ◽  
Author(s):  
T. Paulay
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Response ◽  
Static Loading ◽  
Frame Analysis ◽  
Capacity Design ◽  
Concrete Frames ◽  
Seismic Excitations ◽  
Reinforced Concrete Frames ◽  
High Degree ◽  
Very High

A condensed step by step summary of the application of a recently published capacity design philosophy, as applied to earthquake resisting ductile reinforced concrete frames, is presented. The theoretical inelastic dynamic response of three prototype frames, so designed and subjected to particularly severe seismic excitations, is then reported. It is shown how the predicted maximum actions compare with those used in the design. The design quantities, derived from a modified conventional elastic frame analysis for a code specified lateral static loading, were found to ensure
a very high degree of, and yet economical and practical, protection against hinging in columns at and above the first floor.

scholarly journals An application of capacity design philosophy to gravity load dominated ductile reinforced concrete frames

1978 ◽  
Vol 11 (1) ◽  
pp. 50-61 ◽  
Author(s):  
T. Paulay
Keyword(s):  
Reinforced Concrete ◽  
Lateral Loading ◽  
Capacity Design ◽  
Concrete Frames ◽  
Reinforced Concrete Frames ◽  
Design Philosophy ◽  
Axial Forces ◽  
Earthquake Resistant Design ◽  
Gravity Load ◽  
High Level

Indiscriminate application of the capacity design philosophy can lead to unnecessary or indeed absurd conservatism in the earthquake resistant design of gravity load dominated ductile reinforced concrete frames. Low-rise framed buildings are typical examples. The origin of excessive potential strength with respect to lateral loading is discussed and proposals are made to establish an acceptable upper bound for lateral load carrying capacity in such frames. A technique is presented by which the successive formation of potential plastic hinges, involving partial beam sway mechanisms, can be conveniently assured. While retaining the requirements for energy dissipation in beams, it is postulated that at an acceptable high level of lateral loading the formation of storey mechanisms, necessary to complete the frame sway mechanism, should be tolerable. Examples are given to illustrate the determination of design quantities for bending moments, shear and axial forces for both, beams and columns.

scholarly journals Response of ductile reinforced concrete frames located in Zone C

1980 ◽  
Vol 13 (3) ◽  
pp. 209-225
Author(s):  
T. Paulay ◽  
A. J. Carr ◽  
D. N. Tompkins
Keyword(s):  
Reinforced Concrete ◽  
New Zealand ◽  
Theoretical Prediction ◽  
Seismic Response ◽  
Seismic Zone ◽  
Capacity Design ◽  
Concrete Frames ◽  
Earthquake Loads ◽  
Satisfactory Performance ◽  
Inelastic Seismic Response

The results of theoretical prediction of the inelastic seismic response to selected severe earthquake motions of
f our prototype ductile frames are reported. The structures
 were proportioned in accordance with capacity design principles for loads corresponding with the loading requirements for
seismic Zone C of New Zealand. The effects of P-delta secondary moments on seismic response are briefly reported. A three
 storey frame, in which factored gravity loads rather than specified lateral earthquake loads governed the proportioning
 of members, has been examined in detail. It was found that 
in all frames the intended hierarchy of the energy dissipating mechanisms could be maintained during the full El Centro excitation. The analysis predicted very satisfactory performance for all frames, with a few exceptions, with frames where members were provided with a minimum amount of reinforcement.

scholarly journals Ductile reinforced concrete frames

1975 ◽  
Vol 8 (1) ◽  
pp. 70-90
Author(s):  
R. Park ◽  
T. Paulay
Keyword(s):  
Reinforced Concrete ◽  
American Concrete Institute ◽  
Capacity Design ◽  
Concrete Frames ◽  
Reinforced Concrete Frames ◽  
Flexural Members ◽  
Concrete Confinement ◽  
Curvature Ductility ◽  
Transverse Steel ◽  
Structural Engineers

The 1971 building code of the American Concrete Institute contains an appendix with special provisions for the seismic design of reinforced concrete structures. The provisions are based on the code of the Structural Engineers' Association of California and on research evidence and studies of damage to buildings. This paper comments on a number of
the provisions for reinforced concrete frames and where necessary indicates where improvements appear to be required. The comments on flexural members and columns cover curvature ductility factors resulting from the flexural steel provisions, the transverse steel required for shear strength, concrete confinement, and restraint against buckling of compression bars, and the affect of cyclic loading. The comments on columns also cover the avoidance of plastic hinges in columns by taking into account the probable distribution of bending moments during dynamic excitation and biaxial bending. The comments on beam-column connections touch on the design of shear reinforcement for joint cores. Some observations on capacity design, and suggestions for capacity design procedures, are also made.

Ductile Design Approach for Reinforced Concrete Frames

1986 ◽  
Vol 2 (3) ◽  
pp. 565-619 ◽  
Author(s):  
Robert Park
Keyword(s):  
Reinforced Concrete ◽  
New Zealand ◽  
Flexural Strength ◽  
Shear Failure ◽  
Design Code ◽  
Concrete Frames ◽  
Reinforced Concrete Frames ◽  
Moment Resisting ◽  
Shear Failures ◽  
Strength And Ductility

In the design of multistorey moment-resisting reinforced concrete frames to resist severe earthquakes the emphasis should be on good structural concepts and detailing of reinforcement. Poor structural concepts can lead to major damage or collapse due to column sidesway mechanisms or excessive twisting as a result of soft storeys or lack of structural symmetry or uniformity. Poor detailing of reinforcement can lead to brittle connections, inadequate anchorage of reinforcement, or insufficient transverse reinforcement to prevent shear failure, premature buckling of compressed bars or crushing of compressed concrete. In the seismic provisions of the New Zealand concrete design code special considerations are given to the ratio of column flexural strength to beam flexural strength necessary to reduce the likelihood of plastic hinges forming simultaneously in the top and bottom of columns, the ratio of shear strength to flexural strength necessary to avoid shear failures in beams and columns at large inelastic deformations, the detailing of beams and columns for adequate flexural strength and ductility, and the detailing of beams, columns and beam-column joints for adequate shear resistance and bar anchorage. Differences exist between current United States and New Zealand code provisions for detailing beams and columns for ductility and for the design of beam-column joints.

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