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Seismic response and design of subassemblies for multi-storey prestressed timber buildings.Iqbal, Md Asif January 2011 (has links)
Timber has experienced renewed interests as a sustainable building material in recent times. Although traditionally it has been the prime choice for residential construction in New Zealand and some other parts of the world, its use can be increased significantly in the future through a wider range of applications, particularly when adopting engineered wood material, Research has been started on the development of innovative solutions for multi-storey non-residential timber buildings in recent years and this study is part of that initiative. Application of timber in commercial and office spaces posed some challenges with requirements of large column-free spaces. The current construction practice with timber is not properly suited for structures with the aforementioned required characteristics and new type of structures has to be developed for this type of applications.
Any new structural system has to have adequate capacity for carry the gravity and lateral loads due to occupancy and the environmental effects. Along with wind loading, one of the major sources of lateral loads is earthquakes. New Zealand, being located in a seismically active region, has significant risk of earthquake hazard specially in the central region of the country and any structure has be designed for the seismic loading appropriate for the locality.
There have been some significant developments in precast concrete in terms of solutions for earthquake resistant structures in the last decade. The “Hybrid” concept combining post-tensioning and energy dissipating elements with structural members has been introduced in the late 1990s by the precast concrete industry to achieve moment-resistant connections based on dry jointed ductile connections. Recent research at the University of Canterbury has shown that the concept can be adopted for timber for similar applications. Hybrid timber frames using post-tensioned beams and dissipaters have the potential to allow longer spans and smaller cross sections than other forms of solid timber frames. Buildings with post-tensioned frames and walls can have larger column-free spaces which is a particular advantage for non-residential applications.
While other researchers are focusing on whole structural systems, this research concentrated on the analysis and design of individual members and connections between members or between member and foundation. This thesis extends existing knowledge on the seismic behaviour and response of post-tensioned single walls, columns under uni-direction loads and small scale beam-column joint connections into the response and design of post-tensioned coupled walls, columns under bi-directional loading and full-scale beam-column joints, as well as to generate further insight into practical applications of the design concept for subassemblies. Extensive experimental investigation of walls, column and beam-column joints provided valuable confirmation of the satisfactory performance of these systems. In general, they all exhibited almost complete re-centering capacity and significant energy dissipation, without resulting into structural damage. The different configurations tested also demonstrated the flexibility in design and possibilities for applications in practical structures.
Based on the experimental results, numerical models were developed and refined from previous literature in precast concrete jointed ductile connections to predict the behaviour of post-tensioned timber subassemblies. The calibrated models also suggest the values of relevant parameters for applications in further analysis and design. Section analyses involving those parameters are performed to develop procedures to calculate moment capacities of the subassemblies.
The typical features and geometric configurations the different types of subassemblies are similar with the only major difference in the connection interfaces. With adoption of appropriate values representing the corresponding connection interface and incorporation of the details of geometry and configurations, moment capacities of all the subassemblies can be calculated with the same scheme. That is found to be true for both post-tensioned-only and hybrid specimens and also applied for both uni-directional and bi-directional loading. The common section analysis and moment capacity calculation procedure is applied in the general design approach for subassemblies.
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Ultimate Limit State Response of Reinforced Concrete Columns for Use in Performance-Based Analysis and DesignUrmson, Christopher R. 2010 August 1900 (has links)
The design of reinforced concrete structures for extreme events requires accurate
predictions of the ultimate rotational capacity of critical sections, which is dictated by
the failure mechanisms of shear, hoop fracture, low-cycle fatigue and longitudinal bar
buckling. The purpose of this research is to develop a model for the full compressive
behavior of longitudinal steel including the effects of bar buckling. A computational
algorithm is developed whereby experimental data can be rigorously modeled. An
analytical model is developed from rational mechanics for modeling the complete
compressive stress-strain behavior of steel including local buckling effects. The global
buckling phenomenon is then investigated in which trends are established using a
rigorous computational analysis, and a limit analysis is used to derive simplified design
and analysis equations. The derived buckling models are incorporated into wellestablished
sectional analysis routines to predict full member behavior, and the
application of these routines is demonstrated via an incremental dynamic analysis of a
ten-storey reinforced concrete building. The buckling models and the sectional analysis
routine compare favorably with experimental data. Design recommendations and topics
for further research are presented.
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Performance Based Seismic Design of Lateral Force Resisting SystemMichel, Kenan 06 October 2020 (has links)
Das seitliche Kraftwiderstandssystem, in diesem Fall Stahlbetonkernwände eines 10-stöckigen Gebäudes, das aus Schwerkraftstützen und Scherwänden besteht, wurde linear (unter der Annahme eines linearen elastischen Materialverhaltens von Beton) und nichtlinear gerissen (unter Berücksichtigung des Materialverhaltens von Beton) unter seismische Belastung analysiert. Erst wurde die grundlegenden Methode der äquivalenten Seitenkraft zur Schätzung der seismischen Belastungen benutzt, später wurde die aktuelle Methode The Performance Based Seismic Design verwendet, bei der reale seismische Aufzeichnungen verwendet werden und die Beschleunigungen mithilfe der Software ETABS auf das Gebäude angewendet werden. Nach dem Anwenden der Beschleunigungen wurden die maximal resultierenden Kräfte und Verformungen bewertet. Das Gebäude wurde dann für die maximal resultierenden Kräfte ausgelegt.Der Inhalt des Hauptberichts ist:
- Allgemeine Beschreibung des Gebäudes, seismische Standortinformationen, Standortantwortspektren, Belastung und seismische Kräfte einschließlich Analyse des modalen Antwortspektrums.
- Lineares Design des Modells für Schwerkraft und seismische Belastungen, P-M-Wechselwirkungsdiagramme für den U-Querschnitt aus Stahlbeton, Entwurf einer Längs- und Schubbewehrung der Scherwände und des Koppelbalkens.
- Zwei Varianten des nichtlinearen Modells, bei denen die Kernwand (Scherwände) gemäß jeder Variante entworfen wird, wobei der Einfluss des Dämpfungsmodells auf das nichtlineare dynamische Verhalten sowie der Einfluss des Kopplungsstrahlmodells auf das nichtlineare dynamische Verhalten untersucht werden.
- Entwurfsüberprüfung, erst mit der Definition der Leistungsobjekte und Modell für die Zeitverlaufsanalyse. Es wurden zwei Leistungsziele untersucht: Vollbetriebs- und Lebenssicherheitsprüfungen.
- In zwei Fällen wurde eine zusätzliche Studie zur Reaktion von nicht strukturellen Elementen aufgrund seismischer Belastung durchgeführt: Überprüfung des Vollbetriebs und der Lebenssicherheit.
- Die Durchsetzungszeichnungen wurden fertiggestellt und dem Bericht beigefügt. Schlussfolgerung und Empfehlungen waren am Ende des Berichts. Dies ist wichtig für die Gesellschaft, da die verwendete Methode für die seismische Planung jedes Gebäudes verwendet werden kann. Es könnte ein Holzbau oder ein Mauerwerk sein. Die Gestaltung eines Mauerwerksgehäuses wird Gegenstand eines zukünftigen Forschungsprojekts sein.
Allgemeine Ziele: Lineare und nichtlineare seismische Bemessung von Stahlbetongebäuden unter Verwendung der 'seismischen Bemessung der Leistungsgrundlagen:Acknowledgement 4
PART I: General Information, Site and Loading 5
1. General Information About the Building 5
1.1. Specified Material Properties: 6
1.2. Site Information: 6
1.3. Geometry (Figure I.1): 7
2. Site Seismicity and Design Coefficients 7
2.1. USGS Results 7
2.2. Site Response Spectra 8
2.3. Design Coefficients And Factors For Seismic Force-Resisting Systems 8
3. Loading 9
3.1. Determination Of Seismic Forces 9
3.2. Modal Response Spectrum Analysis 9
3.3. Seismic Load Effects And Combinations 11
PART II: Core Wall Design - Linear Model 12
4. Model of ETABS 12
4.1. Geometry 12
4.2. Gravity Loads 13
4.3. Seismic Loads 15
4.4. Tabulated Selected Results From ETABS Analysis 16
5. P-M Interaction Diagrams 17
5.1. N-S Direction 17
5.2. E-W Direction 19
6. Lateral Force Resisting System, Linear 20
6.1. Longitudinal Reinforcement 20
6.2. Shear Reinforcement 22
6.3. Boundary Elements 24
6.3.1. Transverse Reinforcement Of Boundary Elements 26
6.4. Coupling Beams 27
7. Detailing 30
PART III: Site Response Spectra and Input Ground Motions 31
8. Performance Levels 31
8.1. ASCE 7-16 Target Spectra 31
8.2. Site Response Spectra 34
8.2.1. Ground Motion Conditioning 34
8.2.2. Amplitude Scaling 37
8.2.3. Pseudo Acceleration and Displacement Response Spectra 38
PART IV: Non-Linear Model 40
9. Variant 1 of Non-Linear Model 40
9.1. Complete Core Wall Design for Combined Axial-Flexure 40
9.2. Modal Analysis 43
9.3. Influence of the Damping Model on the Nonlinear Dynamic Response 49
10. Variant 2 of Non-Linear Model 57
10.1. Influence of the Coupling Beam Model on the Nonlinear Dynamic Response 57
10.2. Estimated Roof Displacement 68
PART V: Design Verification 70
11. General 70
11.1. Performance Objectives 70
11.2. Model For Time-History Analyses 71
11.3. Performance Level Verification 71
11.4. Fully Operational Performance Level Verification 71
11.5. Life Safety Performance Level Verification 78
PART VI: Capacity Design of Force Controlled Elements and Regions and Design of Acceleration-Sensitive Nonstructural Elements 87
12. General 87
12.1. Design Verification 87
12.1.1. Full Occupancy Case 87
12.1.2. Life Safety Case 91
12.1.3. Observations on Plots 93
12.2. Acceleration response spectra at roof level 94
12.2.1. Observations on Plots 95
12.3. Core Wall 97
12.4. Design Detail Comparison 103
12.5. Detailed Drawing 103
12.6. Diaphragm 104
12.7. Fire Sprinkler System 117
12.8. Overhanging Projector 119
PART VII: Conclusion 122 / Lateral Force Resisting System, in this case reinforced concrete core walls of a 10 story building consists of gravity columns and shear walls, has been analyzed in linear (assuming linear elastic material behavior of concrete) and nonlinear cracked (considering plastic material behavior of concrete) case, for seismic loading. Starting with the basic method of equivalent lateral force to estimate the seismic loads, then using the up to date method, The Performance Based Seismic Design, which uses real seismic records and apply the accelerations on the building using the software ETABS. After applying the accelerations, maximum resulted forces and deformations have been evaluated. The building then have been designed for the maximum resulted forces.
The contents of the main report are:
- General description of the building, site seismic information, site response spectra, loading and seismic forces including modal response spectrum analysis.
- Linear design of the model for gravity and seismic loads, P-M interaction diagrams developed for U cross section from reinforced concrete, designing longitudinal and shear reinforcement of the shear walls and coupling beam.
- Two variants of Nonlinear model, designing the core wall (shear walls) according to each variant, studying the influence of damping model on the nonlinear dynamic response, as well as the influence of the coupling beam model on the nonlinear dynamic response.
- Design verification, starting with defining the performance objects, and model for time history analysis. Two performance objectives have been studied: Fully operational and Life safety level verifications.
- Additional study was performed for the response of non-structural elements due to seismic loading in two cases: Fully operational and Life safety level verifications.
- Reinforcement Drawings have been finalized and attached to the report.
- Conclusion and recommendations was at the end of the report.
It is important for the society, because the used method could be used for the seismic design of any building. It could be wood building or masonry building. Designing a masonry building case will be the subject of future research project.
Overall objectives: Linear and Nonlinear seismic design of reinforced concrete building using the performance bases seismic design.:Acknowledgement 4
PART I: General Information, Site and Loading 5
1. General Information About the Building 5
1.1. Specified Material Properties: 6
1.2. Site Information: 6
1.3. Geometry (Figure I.1): 7
2. Site Seismicity and Design Coefficients 7
2.1. USGS Results 7
2.2. Site Response Spectra 8
2.3. Design Coefficients And Factors For Seismic Force-Resisting Systems 8
3. Loading 9
3.1. Determination Of Seismic Forces 9
3.2. Modal Response Spectrum Analysis 9
3.3. Seismic Load Effects And Combinations 11
PART II: Core Wall Design - Linear Model 12
4. Model of ETABS 12
4.1. Geometry 12
4.2. Gravity Loads 13
4.3. Seismic Loads 15
4.4. Tabulated Selected Results From ETABS Analysis 16
5. P-M Interaction Diagrams 17
5.1. N-S Direction 17
5.2. E-W Direction 19
6. Lateral Force Resisting System, Linear 20
6.1. Longitudinal Reinforcement 20
6.2. Shear Reinforcement 22
6.3. Boundary Elements 24
6.3.1. Transverse Reinforcement Of Boundary Elements 26
6.4. Coupling Beams 27
7. Detailing 30
PART III: Site Response Spectra and Input Ground Motions 31
8. Performance Levels 31
8.1. ASCE 7-16 Target Spectra 31
8.2. Site Response Spectra 34
8.2.1. Ground Motion Conditioning 34
8.2.2. Amplitude Scaling 37
8.2.3. Pseudo Acceleration and Displacement Response Spectra 38
PART IV: Non-Linear Model 40
9. Variant 1 of Non-Linear Model 40
9.1. Complete Core Wall Design for Combined Axial-Flexure 40
9.2. Modal Analysis 43
9.3. Influence of the Damping Model on the Nonlinear Dynamic Response 49
10. Variant 2 of Non-Linear Model 57
10.1. Influence of the Coupling Beam Model on the Nonlinear Dynamic Response 57
10.2. Estimated Roof Displacement 68
PART V: Design Verification 70
11. General 70
11.1. Performance Objectives 70
11.2. Model For Time-History Analyses 71
11.3. Performance Level Verification 71
11.4. Fully Operational Performance Level Verification 71
11.5. Life Safety Performance Level Verification 78
PART VI: Capacity Design of Force Controlled Elements and Regions and Design of Acceleration-Sensitive Nonstructural Elements 87
12. General 87
12.1. Design Verification 87
12.1.1. Full Occupancy Case 87
12.1.2. Life Safety Case 91
12.1.3. Observations on Plots 93
12.2. Acceleration response spectra at roof level 94
12.2.1. Observations on Plots 95
12.3. Core Wall 97
12.4. Design Detail Comparison 103
12.5. Detailed Drawing 103
12.6. Diaphragm 104
12.7. Fire Sprinkler System 117
12.8. Overhanging Projector 119
PART VII: Conclusion 122
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Use of Cast Modular Components for Concentrically Braced Steel FramesFederico, Giovanni January 2012 (has links)
Cast modular components have been under development for earthquake resistant steel structures. These concepts take advantage of the versatility in geometry afforded with the casting process to create components specifically configured for ductile behavior. Two systems were developed as part of this dissertation research: (1) the Cast Modular Ductile Bracing system (CMDB); (2) the Floating Brace system (FB).The CMDB system makes use of cast components introduced at the ends and the center of the brace to produce a special bracing detail with reliable strength, stiffness and deformation capacity. The system takes advantage of the versatility in geometry offered by the casting process to create configurations that eliminate non-ductile failure modes in favor of stable inelastic deformation capacity. This thesis presents analytical research performed to determine the buckling strength and buckling direction of the bracing element based on the geometries of the cast components. Limiting geometries are determined for the cast components to control the buckling direction. Design formulas for buckling strength are proposed. The Floating Brace system is a new lateral bracing concept developed for steel special concentric braced frames. The concept uses a set of special plate details at the end of the brace to create a stiff, strong and ductile lateral bracing system. The plates are arranged such that some provide direct axial support for high initial stiffness and elimination of fatigue issues for daily service wind loads. The remaining plates are oriented transverse to the brace and thus provide ductile bending response for the rare earthquake event, in which the axial plates become sacrificial. The main bracing member and cast pieces remain elastic or nearly elastic. Thus, following the seismic event, the plates can be replaced. In this thesis, analytical studies using nonlinear finite element analysis are performed to determine the optimum: (a) relative strength of the end connection to the brace; and (b) ratio of strength between axial and transverse plates. Design equations are provided. Prototypes for each concept were developed. Castings were created. Large scale laboratory physical testing was performed as experimental verification (proof of concept) for the two systems.
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Parametric Study of ACI Seismic Design Provisions Through Dynamic Analysis of a Reinforced Concrete Intermediate Moment FrameRichard, Michael James 04 May 2009 (has links)
Reinforced concrete moment-resisting frames are structural systems that work to resist earthquake ground motions through ductile behavior. Their performance is essential to prevent building collapse and loss of life during a seismic event. Seismic building code provisions outline requirements for three categories of reinforced concrete moment-resisting frames: ordinary moment frames, intermediate moment frames, and special moment frames. Extensive research has been conducted on the performance of special moment-resisting frames for areas of high seismic activity such as California. More research is needed on the performance of intermediate moment frames for areas of moderate seismicity because the current code provisions are based on past observation and experience. Adapting dynamic analysis software and applications developed by the Pacific Earthquake Engineering Research (PEER) Group, a representative concrete intermediate moment frame was designed per code provisions and analyzed for specified ground motions in order to calculate the probability of collapse. A parametric study is used to explore the impact of changes in design characteristics and building code requirements on the seismic response and probability of collapse, namely the effect of additional height and the addition of a strong column-weak beam ratio requirement. The results show that the IMF seismic design provisions in ACI 318-08 provide acceptable seismic performance based on current assessment methodology as gravity design appeared to govern the system. Additional height did not negatively impact seismic performance, while the addition of a strong-column weak-beam ratio did not significantly improve results. It is the goal of this project to add insight into the design provisions for intermediate moment frames and to contribute to the technical base for future criteria.
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Seismic Analysis of and Provisions for Dry-Stack Concrete Masonry Wall Systems with Surface Bond in Low-Rise BuildingsEixenberger, Joseph G. 01 April 2017 (has links)
Masonry is one of the oldest forms of construction materials that is still in use today. However, construction practices in the modern age demand faster and more economical practices. Dry-stack masonry, or masonry that doesn't use mortar to bind the blocks together, is a unique system to make masonry more economical. Though several systems of dry-stack masonry have been suggested little to no data exists as most of these systems are patented. This research used dry-stacked normal weight concrete masonry units with an eccentrically placed reinforcement. The wall system is connected through a surface bond and lacks any geometric connection. Previously, research has been conducted on the wall system for its axial compressive capacity, but little information is known about its ability to withstand lateral forces such as earthquakes. Research was conducted on the wall system in order to determine the seismic parameters, including the force reduction factor, overstrength factor, and the displacement amplification factor. To determine these factors the guidelines from the Federal Emergency Management Agency (FEMA) Quantification of Building Seismic Performance Factors 2009 were followed. The guidelines are explicit that both experimental data and computer modeling are needed to quantify these parameters. Experimental data was obtained from a diagonal tension test, and an in-plane shear test. The diagonal tensions test provided preliminary values on the shear modulus and shear resistance. The in-plane shear test was of primary interest and what would be used to verify the computer model. Computer modeling of the wall system was accomplished with Vector 2. Initially the computer modeling was done to reproduce experimental data. Then, a parametric study was performed using the model to see what component of the wall most effected its capacity. This analysis showed that the surface bond was the component of the wall that most affects its capacity. Finally, the computer model was run through the FEMA Far-Field earthquake suite to gather data on the strength and ductility. Values of the force reduction factor, overstrength factor, and displacement amplification factor were determined based on the time history analysis and pushover analysis on the computer model.
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Seismic behaviour of reinforced concrete structures with masonry infillsCrisafulli, Francisco Javier January 1997 (has links)
This thesis focuses on the seismic behaviour of reinforced concrete structures with masonry infills, with particular interest in the development of rational procedures for the design and analysis of this type of structure. The properties of masonry and its constitutive materials were reviewed, giving special emphasis to those aspects which contribute to a better understanding of the strength mechanism. Theoretical procedures were developed for the rational evaluation of the strength of masonry subjected to compressive and shear stresses. A large amount of experimental work related to the behaviour of infilled frames was also reviewed. The main characteristics of the response under lateral loading were discussed for different types of infilled frames and a comprehensive classification of the modes of failure, for both the masonry panel and the surrounding frame, was conducted. In addition, the influence of several parameters which can affect the structural response was evaluated. Two theoretical procedures, with different degree of refinement, are proposed in this study for the analysis of infilled frames. The first procedure is a simple approach, based on the equivalent truss mechanism, which allows the evaluation of the lateral resistance of the infilled frames, considering two different types of failure in the masonry panel, namely, shear-friction and diagonal tension failure. The compressive strength of the diagonal strut is assessed by transforming the shear failure envelope obtained from the modification of the Mann and Muller's theory. This transformation takes into account the inclination of the diagonal strut and neglects the effect of the tensile principal stresses acting on the masonry panel. The second procedure is a refined macroscopic model based on a multi-strut formulation, which is intended to represent more accurately the effect of the masonry panel on the surrounding frame. Since debonding of the mortar joints is the most common type of failure observed in the masonry panel, the formulation of the procedure is specifically developed to represent this situation. The model accounts separately for the compressive and shear behaviour of masonry using a double truss mechanism and a shear spring in each direction. Recommendations are also given for the analysis of infilled frames when a failure due to diagonal tension or crushing of the corners is expected in the panel. A test programme was implemented to investigate the seismic response of infilled frames. The main criterion followed for the design was that the reinforced concrete columns should yield in tension in order to obtain a reasonable ductile response under lateral loading. New reinforcing details were provided in one unit, aimed at enhancing the structural response. These details consisted in tapered beam-column joints with diagonal reinforcement, and additional longitudinal reinforcement in the frame members. The additional bars placed in the columns were not anchored to the foundation in order to produce a weak region at the base of the columns, where most of the plastic deformations were expected to occur. The most important conclusion of the experimental programme is that the response of reinforced concrete frames with masonry infills can be significantly improved by a rational design aimed at reducing the distortion of the masonry panels while plastic deformations arc concentrated in selected regions of the structure. A new design approach is proposed for infillcd frames, in which two cases are considered: cantilever and squat infillcd frames. In the first case, the ductile behaviour is achieved by yielding of the longitudinal reinforcement, which is limited to occur only at the base ofthe columns, and by avoiding large elongations of the remaining parts of the surrounding frame. A pre-cracked connection is induced between the infilled frame and the foundation, where plain round dowels can be placed to control shear sliding. In the second case, ductility is conferred to the structure by allowing controlled sliding of the infillcd frame over the foundation. The applicability of this approach is limited to those cases where the total shear force exceeds the frictional strength of the pre-cracked connection. The effectof pinching of the hysteresis loops in the response of infilled frames subjected to earthquakes was investigated. A parametrie study was conducted using a one-degree-of-freedom oscillator subjected to ground accelerations recorded in five different earthquakes. Results obtained from the dynamic nonlinear analyses indicated that the effect of pinching and the damping model used can significantly influence the response of infilled frames, which normally exhibit a short to medium initial period of free vibration. Therefore, the displacement demand imposed by the earthquake can be larger than that assumed by the seismic codes if they are based on the concept of equal displacement.
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Effect of lateral confining reinforcement on the ductile behaviour of reinforced concrete columnsTanaka, Hitoshi January 1990 (has links)
This thesis is concerned with the effects of lateral confining reinforcement on the ductile behaviour of reinforced concrete columns. The contents of the chapters are summarized as follows. In Chapter one, the general problems in seismic design are discussed and earthquake design methods based on the ductile design approach are described. Japanese, New Zealand and United States design codes are compared. Finally, the scope of this research project is outlined. In Chapter two, after reviewing previous research on confined concrete, the factors which affect the effectiveness of lateral confinement are discussed. Especially the effects of the yield strength of transverse reinforcement, the compressive strength of plain concrete and the strain gradient in the column section due to bending are discussed based on tests which were conducted by the author et al at Kyoto University and Akashi Technological College, Japan. In the axial compression tests on spirally reinforced concrete cylinders (150 mm in diameter by 300 mm in height), the yield strength of transverse reinforcement and the compressive strength of plain concrete were varied from 161 MPa to 1352 MPa and from 17 MPa to 60 MPa, respectively, as experimental parameters. It is found that, when high strength spirals are used as confining reinforcement, the strength and ductility of the confined core concrete are remarkably enhanced but need to be estimated assuming several failure modes which could occur. These are based on the observations that concrete cylinders with high strength spirals suddenly failed at a concrete compressive strain of 2 to 3.5 % due to explosive crushing of the core concrete between the spiral bars or due to bearing failure of the core concrete immediately beneath the spiral bars, while the concrete cylinders with ordinary strength spirals failed in a gentle manner normally observed. In addition, eccentric loading tests were conducted on concrete columns with 200 mm square section confined by square spirals. It is found that the effectiveness of confining reinforcement is reduced by the presence of the strain gradient along the transverse section of column. In Chapter three, the effectiveness of transverse reinforcement with various types of anchorage details which simplify the fabrication of reinforcing cages are investigated. Eight reinforced concrete columns, with either 400 mm or 550 mm square cross sections, were tested subjected to axial compression loading and cyclic lateral loading which simulated a severe earthquake. The transverse reinforcement consisted of arrangements of square perimeter hoops with 135° end hooks, cross ties with 90° and 135° or 180° end hooks, and 'U' and 'J' shaped cross ties and perimeter hoops with tension splices. Conclusions are reached with regard to the effectiveness of the tested anchorage details in the plastic hinge regions of columns designed for earthquake resistance. In Chapter four, the effectiveness of interlocking spirals as transverse reinforcement is studied. Firstly, the general aspects and the related problems of interlocking spirals to provide adequate ductility in the potential plastic hinge region of columns are discussed, referring to the provisions in the New Zealand code,the CALTRANS (California Transportation Authority) code and other related codes. Secondly, based on those discussions, a design method to securely interlock the spirals is proposed. Thirdly, the effectiveness of interlocking spirals is assessed based on column tests conducted as part of this study. Three columns with interlocking spirals and, for comparison, one rectangular column with rectangular hoopsandcross ties, were tested under cyclic horizontal loading which simulated a severe earthquake. The sections of those columns were 400 mm by 600 mm. In Chapter five, analytical models to investigate the buckling behaviour of longitudinal reinforcement restrained by cross ties with 90° and 135° end hooks and by peripheral hoops are proposed. The analyzed results using the proposed models compare well with the experimental observations described in Chapter three. Using those proposed models, a method to check the effectiveness of cross ties with 90° and 135° end hooks is proposed for practical design purposes. In Chapter six, a theory for the prediction of the ultimate longitudinal compressive concrete strain at the stage of first hoop fracture referred to as the "Energy Balance Theory", which has been developed by Mander, Priestley and Park at University of Canterbury, is introduced. After discussing the problems in the "Energy Balance Theory", a modified theory for the prediction of the ultimate longitudinal compressive concrete strain at the stage of first hoop fracture is proposed. The predictions from the modified theory are found to compare well with previous experimental results.
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The Development of High-Performance Post-Tensioned Rocking Systems for the Seismic Design of StructuresMarriott, Dion James January 2009 (has links)
It is not economical, nor practical, to design structures to remain elastic following a major earthquake event. Therefore, traditional seismic design methodologies require structures to respond inelastically by detailing members to accommodate significant plasticity (“plastic hinge zones”). It can be appreciated that, while life-safety of the occupants is ensured, structures conforming to this traditional design philosophy will be subjected to excessive physical damage following an earthquake. Thus, the direct costs associated with repair and the indirect costs associated with business interruption are expected to be great. Adding to this, structures located within a near-field region, close to a surface rupture, can be subjected to large velocity pulses due to a ground motion characteristic known as forward directivity in which a majority of the earthquake’s energy arrives within a very short period of time. Conventionally constructed systems are, in general, unable to efficiently deal with this ground motion.
In the last two decades, advanced solutions have been developed to mitigate structural damage utilising unbonded post-tensioning within jointed, ductile connections, typically combined with hysteretic damping. While there is a growing interest amongst the engineering fraternity towards more advanced systems, their implementation into mainstream practice is slow due to the lack of understanding of unfamiliar technology and the perceived large construction cost. However, even considering such emerging construction technology, these systems are still susceptible to excessive displacement and acceleration demands following a major velocity-pulse earthquake event.
In this research, the behaviour of advanced post-tensioned, dissipating lateral-resisting systems is experimentally and analytically investigated. The information learned is used to develop a robust post-tensioned system for the seismic protection of structures located in zones of high seismicity within near-field or far-field regions.
A series of uniaxial and biaxial cyclic tests are performed on 1/3 scale, post-tensioned rocking bridge piers, followed by high-speed cyclic and dynamic testing of five 1/3 scale, post-tensioned rocking walls with viscous and hysteretic dampers. The experimental testing is carried out to develop and test feasible connection typologies for post-tensioned rocking systems and to improve the understanding of their behaviour under cyclic and dynamic loading.
Insights gained from the experimental testing are use to extensively refine existing analytical modelling techniques. In particular, an existing section analysis for post-tensioned rocking connections is extended to assess the response of post-tensioned viscous systems and post-tensioned connections under biaxial loading. The accuracy of existing macro-models is further improved and a damping model is included to account for contact damping during dynamic loading.
A Direct-Displacement Based Design (DDBD) framework is developed for post-tensioned viscous-hysteretic systems located in near-field and far-field seismic regions. The single-degree-of-freedom (SDOF) procedure is generic and has applications in new design and retrofit, while the multi-degree-of-freedom (MDOF) procedure is developed specifically for continuous bridge systems. Detailed design guidelines and flow-charts are illustrated to encourage the knowledge transfer from this report and to promote the use of emerging technology.
Combining the information gathered from experimental testing, modelling and design, a probabilistic seismic hazard analysis is performed on three post-tensioned viscous-hysteretic bridge systems. In all cases, the post-tensioned bridge systems are shown to be more feasible than a traditional monolithic ductile bridge. Furthermore, while a post-tensioned hysteretic bridge is shown to be the most economic solution, the viscous-hysteretic system becomes more advantageous as the cost of fluid-viscous-dampers reduces.
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A Study on Seismic Design for Infrastructures in a Low Seismicity Region / 地震活動度の低い地域における土木構造物の耐震設計法に関する研究Sherliza Zaini Sooria 26 March 2012 (has links)
Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16820号 / 工博第3541号 / 新制||工||1535(附属図書館) / 29495 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 澤田 純男, 教授 清野 純史, 准教授 五十嵐 晃 / 学位規則第4条第1項該当
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