Design Provision Research Articles

Experimental Investigation of Inelastic Cyclic Buckling and Fracture of Steel Braces

Results from 18 large-scale tests of steel bracing members are presented to examine their inelastic buckling and fracture behavior as related to the seismic design of concentrically braced frames. The brace specimens include square hollow structural shapes (HSS), pipe, and wide-flange sections. The effect of various parameters, including width–thickness and slenderness ratios, cross-section shape, loading history, loading rate, and grout fill on the performance of these braces is investigated. Among these parameters, loading history, width–thickness ratio and slenderness ratio are shown to have the largest influence on brace ductility. The test data suggest that for some HSS and pipe specimens, current seismic design provision limits on maximum width–thickness ratios may not provide sufficient ductility for seismic design. Effects of loading rate are found to be insignificant, and the grout fill is shown to provide a modest improvement in cyclic ductility. Measurements of brace stiffness, tensile strength...

불균형모멘트와 펀칭전단의 상관관계를 고려한 철근콘크리트 무량판 슬래브의 파괴모델

In structural design provision, maximum punching shear stress of slabs is prescribed as combined stress in direct shear occurred by gravity load and eccentric shear occurred by unbalanced moment. This means that the effect of unbalanced moment is considered to decide the punching shear stress. However, from the resistance capacity standpoint, the effect of unbalanced moment strength is not considered for deciding punching shear strength. In this paper, a model considering interrelation between unbalanced moment and punching shear was proposed. In the model, the relation between load effect and resistance capacity in unbalanced moment and punching shear was two-dimensionally expressed. Using the interrelation model, a method how unbalanced moment strength should be considered to decide the punching shear strength was proposed. Additionally, effective width enlargement factors for deciding the unbalanced moment strength of flat plates with shear reinforcements were proposed. The interrelation model proposed in this paper is very effective for the prediction of the behavior of slab-column connection because not only punching shear and unbalanced moment strengths but also failure modes of flat plates can be accurately predicted.

Comparison of code provisions on lap splices

The code provisions on lap splices are critically assessed in the light of 203 beams without transverse reinforcement and 278 beams with transverse reinforcement. For comparison, the provisions given in the ACI 318, Eurocode 2, and TS 500 Codes are considered. The ACI Committee 408 recommended provision and a new proposal are also taken into account throughout the assessment. The comparison with real beam tests where the splice region was subjected to constant moment indicates that current provisions in the Codes do not agree acceptably with test results. The steel stress prediction graphs calculated by means of the Code provisions show high scatter and remain unsafe especially for test data without transverse reinforcement. Both the recent recommended provision by ACI Committee 408 and a new design expression proposed by the author have much less scatter with fewer unsafe predictions. The simplified design provision proposed by ACI Committee 408 does not yield similar results to that of the advanced design provision proposed by the same committee and therefore it could conveniently be replaced with the simpler equation proposed by the author.

Planning inclusive and sustainable urban regeneration: Balancing a visitor-based economy with local needs in the city of York, UK

This paper presents findings from the research project 'Inclusive and Sustainable Infrastructure for Tourism and Urban Regeneration' (InSITU). It has been conducted in historic urban areas where the physical environment is in need of regeneration and leisure and tourism can create new uses for redundant or under-used premises, generate jobs and stimulate investment. There is also a risk, however, that development may alienate the very people who are supposed to benefit most from regeneration. InSITU captured the knowledge, views and preferences of those who are likely to be affected, so that workable solutions can be designed and benefits maximised. This was achieved through the innovative application of Geographic Information Systems for Participation (GIS-P) to widen participation in urban design and heritage provision and allows that participation to feed more directly into the policy process. The paper outlines two cases in York. One demonstrates the role local people have in outlining the benefits and drawbacks of a public space, and change that might be made to it (problem definition). The second considers the role of local people in appraising the utility of a proposed cycle/pedestrian route on the site of a former factory (option generation/appraisal). The benefits and limitations of the GIS-P approach are assessed: benefits are inclusion of hard to reach groups in the process, ease and clarity of result dissemination and level of detail captured. Limitations include prioritising conflicting stakeholder concerns, the stage of the policy process at which stakeholders are consulted and the level at which this methodology and subsequent findings are useful (local/regional). Finally, an assessment is made of to whom these findings are useful (to policy makers and/or developers).

변위연성도 기반 철근콘크리트 교각의 한정연성 내진 설계법과 성능평가 방법

Until recently Korea is considered to be immune from the earthquake hazard because it is located for away from the active fault. However, we have noticed that recent strong earthquakes inflicted enormous losses on human lives and nation`s economy all over the world. Hence, there has been raised the importance of the earthquake resistant design for various infrastructures. In this research, new methodologies for the seismic design and performance assessment of reinforced concrete(RC) bridge pier were proposed from experimental results of 82 circular RC bridge piers and 54 rectangular RC bridge piers tested in domestic and aboard. New seismic design method was based on the concept of the limited ductile design, which could be practically used for low or moderate seismic regions like Korea. Further study for the seismic safety of RC bridge piers was carried out to enhance the seismic performance of aged RC bridge piers, which were designed and constructed before implementing the 1992 seismic design provision in Korea. New formula for the seismic performance assessment of RC bridge piers was proposed and practically used for the decision on the need of repair and retrofit of many aged RC bridge piers.

사각단면 철근콘크리트 교각의 심부구속철근비 제안

Many losses of life and extensive damage of social infrastructures have occurred due to moderate and strong earthquakes all over the world. In this research various design parameters have been evaluated to develop a rational seismic design code of rectangular reinforced concrete(RC) bridge piers. It was confirmed from this study that the axial force ratio and longitudinal steel ratio were most influencing design parameters on the seismic displacement ductility from experimental results of 54 rectangular RC bridge piers, which were tested at domestic and foregin countries. However, these important parameters are not considered in the confinement steel ratio of Korea Highway Bridge Design Specification(KHBDS). The objective of this study is to propose a rational design provision for the transverse reinforcement of rectangular RC bridge piers. New confinement steel ratio is proposed by reflecting the effect of the axial force and longitudinal steel into the current code of KHBDS. furthermore, minimum transverse confinement steel ratio is also proposed to avoid a probable buckling of longitudinal reinforcing steels of RC bridge piers with a relatively low axial force. New practical code can alleviate the rebar congestion in the plastic hinge region of RC bridge pier, which contributes to construct RC bridge piers in a simple and economic way.

Architecture for the Management and Presentation of Communication Network Performance Data

Packet-based data networks such as British Telecommunications (BT) plc's switched multimegabit data service (SMOS) have performance that varies with customer behavior, network design, and network provision. This paper describes a system researched to monitor such networks from the customer's perspective, but on behalf of the operator. The information generated allows the operator to determine whether the network is performing correctly or whether changes or customer load will require the network to be changed in some way. Such networks are increasingly important as many parts of the Internet are built on similar technologies. The paper specifically considers an architecture that encompasses all the main functionality involved in performance management of networks. Consideration is given to the management and dissemination of the data collected. A database to enhance network data mining performance is described. A method to identify the periods of significance in the measurement data based on a statistical test and a neural network is incorporated into a realization of the architecture. In addition, a novel mechanism for the real-time presentation of the network performance data in an operator-friendly manner is given.

A general characterization of interim efficient mechanisms for independent linear environments

We consider the class of Bayesian environments with independent types, and utility functions which are both quasi-linear in a private good and linear in a one-dimensional private-value type parameter. We call these independent linear environments. For these environments, we fully characterize interim efficient allocation rules which satisfy interim incentive compatibility and interim individual rationality constraints. We also prove that they correspond to decision rules based on virtual surplus maximization, together with the appropriate incentive taxes. We illustrate these techniques with applications to auction design and public good provision.

Design of Lap-Spliced Bars: Is Simplification Possible?

While the estimation accuracy of the strength of lap splices has been improving, the complexity of design for reinforcement development has progressively increased. This research study investigates the development of a simple and reliable design expression. Equations on development and splices of reinforcement in ACI 318-05 along with other design proposals are critically assessed in light of 203 unconfined and 278 confined beam tests where the splice region was subjected to constant moment. A simple design provision is developed that is based on a physical model of tension cracking of concrete in the lap spliced region. This new expression is shown to be consistent with current design practice, applicable to existing test results, and simple in application.

Biased managers, organizational design, and incentive provision

We model the tradeoff between the balance and the strength of incentives implicit in the choice between hierarchical and matrix organizational structures. We show that managerial biases determine which structure is optimal: hierarchical forms are preferred when biases are low, while matrix structures are preferred when biases are high.

Biased Managers, Organizational Design, and Incentive Provision

We model the tradeoff between the balance and the strength of incentives implicit in the choice between hierarchical and matrix organizational structures. We show that managerial biases determine which structure is optimal: hierarchical forms are preferred when biases are low, while matrix structures are preferred when biases are high.

프리텐션 PSC부재의 전달길이 해석 및 예측에 관한 연구

The transfer of prestress force in pretensioned prestressed concrete (PSC) members is of great concern because it affects directly the distribution of stress around the transfer zone. The design provision of current design code on the transfer length considers only the prestress intensity and the diameter of prestressing steels. However, other factors such as concrete compressive strength and concrete cover may affect greatly the transfer length. The purpose of the present paper is to explore the various factors that affect the transfer length in pretensioned PSC members. The bond stress-slip relation between prestressing steel and concrete was modeled first from experimental data and then this model was incorporated into the interface element. The interface element was used to perform the finite element analysis for pretensioned PSC members. The results indicate that the compressive strength and concrete cover are also very important parameters which affect the transfer length greatly. This means that the current design code, which considers only the effective prestress and diameter of prestressing steel, must be improved to take into account the other important variables of compressive strength and concrete cover. The present study allows more realistic analysis and design of pretensioned PSC members.

Behaviour of high-strength concrete flexural walls

This paper discusses the behaviour and strength of high-strength (> 68·7 MPa) concrete structural walls. The information will also enhance the current database for the improvement of design recommendations. The objectives of the present test were to investigate the effect of parameters such as axial load and transverse (horizontal) reinforcement on the behaviour of high-strength concrete flexural walls, and to examine the applicability of the ACI Building Code strength design provision for predicting the strength of high-strength concrete walls. To attain the objectives, five one-third scale framed wall specimens were designed, constructed, and tested. The walls tested were 1·20 m wide, 2·00 m high and 85 mm thick with 180 mm × 180 mm boundary elements. The axial-load ratio was found to have a significant effect on the flexural strength, failure mode and ductility of high-strength concrete structural walls. At a higher level of vertical load, lateral resistance of the wall was improved, but ductility and deformability decreased. The reduction of the horizontal web reinforcement to almost half of the value specified by the ACI Building Codes does not significantly affect the failure load and the hysteretic behaviour.

Behaviour of high-strength concrete flexural walls

This paper discusses the behaviour and strength of high-strength (> 68·7 MPa) concrete structural walls. The information will also enhance the current database for the improvement of design recommendations. The objectives of the present test were to investigate the effect of parameters such as axial load and transverse (horizontal) reinforcement on the behaviour of high-strength concrete flexural walls, and to examine the applicability of the ACI Building Code strength design provision for predicting the strength of high-strength concrete walls. To attain the objectives, five one-third scale framed wall specimens were designed, constructed, and tested. The walls tested were 1·20 m wide, 2·00 m high and 85 mm thick with 180 mm × 180 mm boundary elements. The axial-load ratio was found to have a significant effect on the flexural strength, failure mode and ductility of high-strength concrete structural walls. At a higher level of vertical load, lateral resistance of the wall was improved, but ductility and deformability decreased. The reduction of the horizontal web reinforcement to almost half of the value specified by the ACI Building Codes does not significantly affect the failure load and the hysteretic behaviour.

Financial system design and liquidity provision by banks and markets in a dynamic economy

This paper contributes to the literature on financial system design by comparing markets and banks in a dynamic economy. Investors trade off their liquidity needs against the high returns on illiquid investments. Both the banking system and the market can provide partial liquidity insurance to investors. We consider full market participation as well as limited market participation. We demonstrate that the full-participation market with intergenerational trading can provide more liquidity than one without. Insurance is provided through wealth transfer across generations, instead of cross-subsidization across contemporaneous types as is the case in the finite economy. Given a full-participation market that allows trading across generations, only banks with initial capital can provide additional liquidity. In a limited-participation market with uncertainty about trading types, an intergenerational bank (with or without initial capital) provides additional insurance to investors. The need for trade is eliminated. Finally, if there is no uncertainty about trading types, then an intergenerational bank with initial capital eliminates the need for trading and improves welfare for all. An intergenerational bank without initial capital improves welfare for people who do not trade.

고강도 철근콘크리트 깊은 보의 전단거동에 대한 개구부 크기 및 위치의 영향

초록 · 키워드 목차 오류제보하기 등록된 정보가 없습니다. ABSTRACT1. 서론2. 연구방법 및 범위3. 실험결과 및 비교ㆍ분석4. 극한 전단내력 예측모델5. 결론참고문헌요약

철근의 겹침이음을 고려한 철근콘크리트 교각의 내진성능평가

1992년 도로교 설계기준의 내진설계규정이 도입되기 이전에 건설된 대부분의 교각은 소성힌지구간에서 주철근의 겹침이음이 이루어졌다. 그러나 비탄성 반복하중하에서 겹침이음부의 갑작스런 취성파괴가 발생할 수 있다. 이 연구는 반복하중을 받는 주철근이 겹침이음된 철근콘크리트 교각의 비선형 이력거동과 연성능력을 해석적으로 파악하는데 그 목적이 있다. 이를 위해서 비선형 해석프로그램인 RCAHEST가 사용되었으며 겹침이음된 철근의 거동을 예측하기 위해서 겹침이음 철근요소를 개발하였다. 또한 겹침이음된 철근의 최대 철근응력과 슬립이 고려되었다. 이 연구에서는 주철근의 겹침이음을 갖는 철근콘트리트 교각의 내진성능평가를 위해 제안한 해석기법을 신뢰성 있는 연구자의 실험결과와 비교하여 그 타당성을 검증하였다. Lap splices were located in the plastic hinge region of most bridge piers that were constructed before the adoption of the seismic design provision of Korea Highway Design Specification on 1992. But sudden brittle failure of lap splices may occur under inelastic cyclic loading. The purpose of this study is to analytically predict nonlinear hysteretic behavior and ductility capacity of reinforced concrete bridge piers with lap splices under cyclic loading. For this purpose, a nonlinear analysis program, RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology) is used. Lap spliced bar element is developed to predict behaviors of lap spliced bar. Maximum bar stress and slip of lap spliced bar is also considered, The proposed numerical method for seismic performance evaluation of reinforced concrete bridge piers with lap splices is verified by comparison with reliable experimental results.

불균형 휨모멘트를 받는 플랫 플레이트-기둥 외부접합부의 강도

초록·키워드 목차 오류제보하기 등록된 정보가 없습니다. ABSTRACT1. 서론2. 해석 프로그램3. 변수연구4. 외부접합부의 강도산정5. 외부접합부 강도산정모델의 검증 및 근사법6. 결론참고문헌요약

Human Resource Management, Corporate Performance and Employee Wellbeing: Building the Worker into HRM

Two main approaches to human resource management (HRM) are identified: one focusing on the organisational concern for the relationship between HRM and performance, the other mounting a critique of HRM. It is argued that both pay lip service to, but largely neglect worker reactions to HRM. The case is made for building the worker into the analysis of HRM, on the one hand, by incorporating worker attitudes and behaviour in the study of the HRM-performance relationship, and on the other, by paying serious attention to the association between HRM and worker-related outcomes. Evidence is presented to suggest that worker attitudes and behaviour mediate the HRM-performance relationship and that certain HR practices are associated with higher work and life satisfaction. These practices include job design, direct participation and information provision that are associated with higher performance; but work satisfaction is also associated with equal opportunities, family-friendly and anti-harassment practices. It is suggested that a more worker-friendly HRM can best be applied in the context of a partnership or mutual gains framework.

An International Perspective on Hospital Nurses’ Work Environments: The Case for Reform

The current nursing shortage, high hospital-nurse job dissatisfaction, and reports of uneven quality of hospital care are not uniquely American phenomena. This article presents reports from 43,000 nurses at more than 700 hospitals in the United States, Canada, England, Scotland, and Germany during 1998 and 1999. Nurses in countries with distinctly different health care systems report similar shortcomings in their work environments and the quality of hospital care. Although nurse and physician competence and nurse-physician relationships appear satisfactory, core problems in work design and workforce management threaten care provision. Resolving these issues, which are amenable to managerial intervention, is essential to preserve patient safety and provide care of consistently high quality.