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Performance-based wind design of tall buildings: concepts, frameworks, and opportunities

  • Bezabeh, Matiyas A.;Bitsuamlak, Girma T.;Tesfamariam, Solomon
    • Wind and Structures
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    • v.31 no.2
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    • pp.103-142
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    • 2020
  • One of the next frontiers in structural wind engineering is the design of tall buildings using performance-based approaches. Currently, tall buildings are being designed using provisions in the building codes and standards to meet an acceptable level of public safety and serviceability. However, recent studies in wind and earthquake engineering have highlighted the conceptual and practical limitations of the code-oriented design methods. Performance-based wind design (PBWD) is the logical extension of the current wind design approaches to overcome these limitations. Towards the development of PBWD, in this paper, we systematically review the advances made in this field, highlight the research gaps, and provide a basis for future research. Initially, the anatomy of the Wind Loading Chain is presented, in which emphasis was given to the early works of Alan G. Davenport. Next, the current state of practice to design tall buildings for wind load is presented, and its limitations are highlighted. Following this, we critically review the state of development of PBWD. Our review on PBWD covers the existing design frameworks and studies conducted on the nonlinear response of structures under wind loads. Thereafter, to provide a basis for future research, the nonlinear response of simple yielding systems under long-duration turbulent wind loads is studied in two phases. The first phase investigates the issue of damage accumulation in conventional structural systems characterized by elastic-plastic, bilinear, pinching, degrading, and deteriorating hysteretic models. The second phase introduces methods to develop new performance objectives for PBWD based on joint peak and residual deformation demands. In this context, the utility of multi-variate demand modeling using copulas and kernel density estimation techniques is presented. This paper also presents joined fragility curves based on the results of incremental dynamic analysis. Subsequently, the efficiency of tuned mass dampers and self-centering systems in controlling the accumulation of damage in wind-excited structural systems are investigated. The role and the need for explicit modeling of uncertainties in PBWD are also discussed with a case study example. Lastly, two unified PBWD frameworks are proposed by adapting and revisiting the Wind Loading Chain. This paper concludes with a summary and a proposal for future research.

Velocity-porosity relationships in oceanic basalt from eastern flank of the Juan de Fuca Ridge: The effect of crack closure on seismic velocity (Juan do Fuca 해저산맥의 동쪽 측면으로부터 얻은 해양성 현무암의 속도와 공극률의 관계: 균열닫힘이 탄성파 속도에 미치는 영향)

  • Tsuji, Takeshi;Iturrino, Gerardo J.
    • Geophysics and Geophysical Exploration
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    • v.11 no.1
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    • pp.41-51
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    • 2008
  • To construct in situ velocity-porosity relationships for oceanic basalt, considering crack features, P- and S-wave velocity measurements on basaltic samples obtained from the eastern flank of the Juan de Fuca Ridge were carried out under confining pressures up to 40 MPa. Assuming that the changes in velocities with confining pressures are originated by micro-crack closure, we estimated micro-crack aspect ratio spectra using the Kuster-$Toks{\ddot{o}}z$ theory. The result demonstrates that the normalised aspect ratio spectra of the different samples have similar characteristics. From the normalised aspect ratio spectrum, we then constructed theoretical velocity-porosity relationships by calculating an aspect ratio spectrum for each porosity. In addition, by considering micro-crack closure due to confining pressure, a velocity-porosity relationship as a function of confining pressure could be obtained. The theoretical relationships that take into account the aspect ratio spectra are consistent with the observed relationships for over 100 discrete samples measured at atmospheric pressure, and the commonly observed pressure dependent relationships for a wide porosity range. The agreement between the laboratory-derived data and theoretically estimated values demonstrates that the velocity-porosity relationships of the basaltic samples obtained from the eastern flank of the Juan de Fuca Ridge, and their pressure dependence, can be described by the crack features (i.e. normalised aspect ratio spectra) and crack closure.

Role of Mesophyll Morphology in Determination of Leaf Photosynthesis in Field Grown Soybeans (포장생육대두의 엽광합성과정에서 엽육세포 형태의 역할)

  • Yun, Jin Il;Lauer, Michael J.;Taylo, S.Elwynn
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.36 no.6
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    • pp.560-567
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    • 1991
  • Photosynthetic variation in field grown soybean [Glycine max (L.) Merr. cv Hodgson78] was studied in relation to leaf anatomical variation. Variations in mesophyll morphology were accentuated by manipulating source and sink size. At R3 stage, two treatments were started: one was thinning and continu-ous debranching(6. 5 plants rather than 26 plants per m of row and remaining plants were debranched weekly), and the other was continuous partial depodding (allowing only one pod to develop at each mainstem node). Gas exchange characteristics, mesophyll cell volume and surface area per unit leaf surface, and microclimatic parameters were measured on the intact terminal leaflet at the 10th node. Observations were made 5 times with 3 to 4 day intervals starting R4 stage. Two models were used to compute leaf photosynthetic rates: one considered no effect of mesophyll morphology on photosynthesis, and the other considered potential effects of variations in mesophyll cell volume and surface area on diffusion and biochemical processes. Seventy nine percent of total photosynthetic variations observed in the experiment was explained by the latter, while 69% of the same variations was explained by the former model. By incorporating the mesophyll morphology concept, the predictability was improved by 14.6% in the field condition. Additional Index Words: photosynthesis model, leaf anatomy, Glycine max (L.) Merr., mesophyll surface area, mesophyll cell volume.

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Recovery of Palladium (Pd) from Spent Catalyst by Dry and Wet Method and Re-preparation of Pd/C Catalyst from Recovered Pd (폐촉매로부터 Pd회수 및 이를 이용한 Pd/C 촉매 재제조 기술 개발)

  • Kim, Ji Sun;Kwon, Ji Soo;Baek, Jae Ho;Lee, Man sig
    • Applied Chemistry for Engineering
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    • v.29 no.4
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    • pp.376-381
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    • 2018
  • The purpose of this study is to investigate and optimize an effectiveness process for the recovery of Pd from the spent Pd/C catalyst by the process of hydrogenation of maleic anhydride over Pd/C. Pd solution recovered from Pd/C catalyst was used to prepare Pd/C catalysts. Their characteristics were compared to those of Pd/C catalyst prepared by using a reagent grade precursor solution. Pd in the spent catalyst was leached by the modified process with dry and wet methods to obtain the high recovery ratio of Pd. The burn-out of carbon in the spent Pd/C catalyst was carried out in the rage of $600-900^{\circ}C$. Pd content of carbonized catalyst was confirmed by XRF and ICP. Pd was extracted from carbonized spent catalysts with acid solutions of 1,2 and 4 M HCl at a leaching temperature of $90^{\circ}C$ for 2 h. The high recovery ratio of Pd was shown as 92.4% that leached in 4 M HCl. Also Pd/C catalysts were prepared by using the leached solution and the reagent grade of $H_2PdCl_4$ as a precursor solution and the characteristics were analyzed by XRD, CO-chemisorption and FE-TEM. As a result, the dispersion of the catalyst prepared by using the leached solution was 34.6%, which was found to be equal to or more than that of the Pd/C catalyst prepared by the reagent grade precursor solution.

Legislative Approaches to Terminal Care Issue in the U.S.A. - Acts on Terminal Health-Care Decision (말기의료에 관한 미국 법제의 연구 - 말기의료결정 제도를 중심으로)

  • Suk, HeeTae
    • The Korean Society of Law and Medicine
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    • v.14 no.1
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    • pp.355-401
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    • 2013
  • The first legislation for terminal health-care decision was California's Natural Death Act (NDA) of 1976 that permitted any adult person to execute a directive directing the withholding or withdrawal of life-sustaining procedures. Advance directive legislation has subsequently progressed on a state-by-state basis. By 1992, all 50 states, as well as the District of Columbia, had passed legislation to legalize some form of advance directive. This state legislation, however, has resulted in an often fragmented, incomplete, and sometimes inconsistent set of rules. Statutes enacted within a state often conflict and conflicts between statutes of different states are common. In an increasingly mobile society where an advance health-care directive given in one state must frequently be implemented in another, there is a need for greater uniformity. In 1993, the Uniform Law Commissioners approved the Uniform Health-Care Decisions Act (UHCDA) in order to bring order to the existing chaos. Unfortunately, the Commissioners waited too long to act. By the time the UHCDA was approved, nearly all states had passed legislation governing advance directives. Consequently, the UHCDA has achieved only a limited success, picking up but one or two enactments a year. The UHCDA is currently in effect in around 10 states: Alabama, Alaska, California, Delaware, Hawaii, Kansas, Maine, Mississippi, New Mexico, Tennessee, Wyoming. In these states the previous laws related to the subjects have been all repealed. The overall objective of the UHCDA is to encourage the making and enforcement of advance health care directives including living will or individual instruction, power of health-care attorney and to provide a means for making health care decisions for those who have failed to plan. The U. S. House of Representatives in 1991 enacted the Patient Self-Determination Act (PSDA). The Act stipulates that all hospitals receiving Medicaid or Medicare reimbursement must ascertain whether patients have or wish to have advance directives. The Patient Self- Determination Act does not create or legalize advance directives; rather it validates their existence in each of the states. Now in America, terminal health-care decision or advance directive for health care is common and universal system. The problem, however, is how to let more people use these good tools to make their lives more beautiful and honorable.

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Relationships of TVOC with Several Aromatic Hydrocarbon Constituents at Preschool Facilities

  • Yoon, Chung-Sik;Choi, In-Ja;Ha, Kwon-Chul;Park, Dong-Uk;Park, Doo-Yong
    • Journal of Environmental Health Sciences
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    • v.32 no.5 s.92
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    • pp.404-411
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    • 2006
  • 이 연구의 목적은 유치원에서 총 휘발성 유기화합물의 농도를 평가하고, 총 휘발성 유기화합물 농도와 대표적인 8개 방향족 화합물의 상관관계를 조사하는데 있다. 도시에 위치한 11개 유치원의 실내와 실외에서 각각 30개, 11개의 지역시료를, 시골에 위치한 4개 유치원에서는 각각 10개, 4개의 시료를 테낙스 튜브를 이용하여 오전에 1-2시간 채취하였다. 채취한 시료는 열탈착하여 가스크로마토그래피-질량분석기로 분석하였다. 13가지 물질을 각각의 표준물질로 개별 정량하여 이중 빈번히 발견되는 8가지 방향족 유기화합물은 상관관계 평가에 사용하였다. 총 휘발성 유기화합물은 톨루엔을 기준으로 정량하였다. 도시에 위치한 유치원 실내의 총 휘발성 유기화합물 농도가 높았고, 조사 건수의 50%가 환경부 및 교육인적자원부의 가이드라인($400{\mu}g/m^{3}$)을 초과하였다. 도시지역의 유치원 실내 및 실외의 기하평균은 각각 $387.9{\mu}g/m^{3}$$134.9{\mu}g/m^{3}$이었고, 시골지역 유치원에서는 각각 $189.6{\mu}g/m^{3},;74.4{\mu}g/m^{3}$이었다. 톨루엔, 크실렌, 에틸벤젠, 정량한 유기 화합물 총합, 총 휘발성 유기화합물은 기하정규분포를 하였다. 벤젠, 톨루엔, 에틸벤젠, 크실렌(BTEX)은 도시에 위치한 유치원에서 농도도 높고, 총 휘발성 유기화합물중 함량도 높았고, 시골지역에서는 농도와 상대적 함량이 낮았다. 도시지역에서는 총 휘발성 유기화합물 중 BTEX의 비중이 25.2%였고 정량한 13가지 유기화합물 중에서는 35.6%를 차지하였다. BTEX 각각 개별물질은 미국 환경보호청이 제시하는 일일 노출 기준량(Reference Concentration; RfC) 보다는 현저히 낮았다. 총 휘발성 유기화합물읜 농도는 실내가 실외 보다 높았다(I/O ratio 2.5). BTEX의 상대적 함량도 실내가 실외보다 높아 실내에도 발생원이 있음을 암시하고 있다. 자료 분석결과 유치원 실내의 벤젠은 실외로부터 유입되고 있었고, 톨루엔, 에틸벤젠, 크실렌은 실외뿐 아니라 실내에서도 발생하고 있었다. 정량한 8개 화합물 각각과 총 휘발성 유기화합물의 스피어만 상관계수는 벤젠을 제외하고는 모두 유의하였다. 이중 톨루엔과 크실렌은 총 휘발성 유기화합물과 좋은 상관성 (톨루엔 0.76, 크실렌, 0.87)을 나타내었다. 이 연구는 톨루엔과 크실렌이 총 휘발성 유기화합물의 좋은 지표를 사용될 있고, 톨루엔, 에틸벤젠, 크실렌 등 많은 휘발성 유기화합물의 발생원은 실외뿐 아니라 실내에도 있음을 나타내고 있다.

An Economic Feasibility Study of AR CDM project in North Korea (북한 지역을 대상으로 한 조림 CDM 사업의 경제적 타당성 연구)

  • Han, Ki Joo;Youn, Yeo-Chang
    • Journal of Korean Society of Forest Science
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    • v.96 no.3
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    • pp.235-244
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    • 2007
  • Potentials of AR CDM project in North Korea are assessed and feasible land area for AR CDM project is estimated. According to our estimation, There could be 515,000 hectares of forest lands deforested before 1990 in North Korea and 8,854 hectares at the regional level of Gae-sung City, which are eligible for AR CDM project, based on researches of satellite image analyses conducted from 1980's to 1990's. A baseline scenario assumed 44.73 tones of carbon stored in soil per hectare with no vegetation above ground remained during the project period following the default value of IPCC's Good Practice Guidance for LULUCF considering soil structure, climate and land use of the project area. The scenario also assumes that black rocust (Robinia pseudoacacia) is planted and the CDM project is implemented for 20 years. The costs for producing greenhouse gases CER (certified emission reduction) credits include costs of tree planting and forest management, and costs of project negotiation and transactions for issuing the credits. It is estimated that 376 tones of carbon dioxide per hectare can be accumulated and 503 temporary CER credits per hectare and 265 long-term CER credits per hectare could be produced during the project period. It is estimated to cost US$ 4.04 and US$ 7.67 to provide one unit of temporary credit and long-term credit, respectively. These values can be regarded as the cost of conferring emission commitment of a country or a private entity. However, it is not clear which option is better economically because the replacement periods are different in these two cases.

Effects of Non-ionic Surfactant Supplementation on Ruminal Fermentation, Nutrient Digestibility and Performance of Beef Steers Fed High-roughage Diets

  • Ahn, Gyu-chul;Kim, Jeong-hoon;Park, Eun-kyu;Oh, Young-Kyoon;Lee, Gang-yeon;Lee, Jung-il;Kim, Chong-min;Park, Keun-kyu
    • Asian-Australasian Journal of Animal Sciences
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    • v.22 no.7
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    • pp.993-1004
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    • 2009
  • Three experiments were conducted to determine the effects of non-ionic surfactant (NIS) supplementation on ruminal fermentation, nutrient digestibility and performance of beef steers fed high-roughage diets. The objective of experiment 1 was to investigate the effects of NIS supplementation on in vitro ruminal fermentation of cultures administered with corn and barley as grain substrate and rice straw and timothy hay as roughage substrate. The in vivo ruminal fermentation, nitrogen balance and digestibility of nutrients were also examined with steers fed a high-roughage diet in experiment 2. The aim of experiment 3 was to determine the responses to NIS of growing steers fed a high-roughage diet. In experiment 1, ammonia nitrogen concentration for NIS supplementation was higher (p<0.05) than for the control with all substrates. However, concentrations of total volatile fatty acid (VFA), acetate, butyrate and valerate of the incubated roughage substrates, rice straw and timothy hay, were higher (p<0.05) for NIS supplementation than for the control whereas VFA concentrations in the cultures of corn and barley were unaffected. These results indicated that effects of NIS on ruminal fermentation are diet dependent, specifically on roughage sources. In experiment 2, ruminal pH of steers supplemented with NIS was lower (p<0.05) than the control. Ruminal concentrations of ammonia nitrogen, acetate, total VFA and urinary concentrations of purine derivatives were increased (p<0.05) by NIS supplementation. In experiment 3, supplementation of NIS increased (p<0.05) intakes of total feed and corn silage, average daily gain, and feed efficiency of growing steers although they varied depending on supplementation level. Due to the roughage-specific feature of NIS effects, NIS appears to enhance ruminal fermentation of fibrous parts of feeds and, consequently, performance of steers fed a high-roughage diet.

An Intervention Model to Help Clients to Seek Their Own Hope Experiences: The Narrative Communication Model of Hope Seeking Intervention

  • Kim, Dal Sook;Kim, Hesook Suzie;Thorne, Sally
    • Journal of Hospice and Palliative Care
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    • v.20 no.1
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    • pp.1-7
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    • 2017
  • The paper describes The Narrative Communication Model of Hope Seeking Intervention developed by the authors as an approach to help clients to have individually specific hope experiences. The Model is founded upon the existential conceptualization of hope that views hope as subjective, unique experiences of meaning and processes. The Model has been developed based on the findings both in the literature and the authors' work on the nature of hope and hope experiences and integrating the concept of hope as subjective meanings and experiences, the processes of story-telling and the concept of narrative configuration as a way to engage in person-specific experiences, and person-centered communication. The results of the experiences with the application of the model in a study are used to clarify the model further. The Model incorporating story-telling and narrative construction through person-centered communication is identified in three components-the story-telling, the narrative intervention, and the communication components. These components are processed as an intervention to culminate into person-specific hope experiences in which active participation of clients as the story-teller and of interventionist as the communicative facilitator is required to produce narratives of hope with individual specific thematic plots that become the basis for hope experiences. The application of the Model has shown positive outcomes in clients with successful seeking of own hope experiences. The success of the Model application seems to depend upon interventionists' understanding of the model and the competency with the application of person-centered communication strategies.

Effects of Leaf and Pod Removal on Photosynthesis and Assimilate Partition in Soybean (적엽ㆍ제협처리가 콩의 광합성과 동화물질 배분에 미치는 영향)

  • Woong Tae, Kim;Rak Chun, Seong;Harry C, Minor
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.38 no.2
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    • pp.159-165
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    • 1993
  • To clarify the effects of sink demand for assimilate on leaf photosynthetic rate, tissue composition, and leaf senescence of soybean [Glycine max (L.) Merr.] J plants, pod and leaf tissues were removed at growth stage $R^3$. Plant responses were measured every 10days from 2 through 42days following treatment. Leaves of depodded plants exhibited increased starch and chlorophyll contents and specific leaf weight. Stomatal resistance was also increased and leaf photosynthetic rate was reduced. Dry weight of vegetative tissues except leaves was increased by pod removal. Leaf removal resulted in a decreased starch content of leaves from 22 to 42days after treatment and that of roots at all sampling times. Specific leaf weight was decreased while leaf photosynthetic rate was increased. Stomatal resistance and chlorophyll content were little affected. Weight per seed was decreased 3.0% by leaf removal. Except for the seed, tissue protein contents were increased by pod removal but decreased by leaf removal, however, seed protein content was not affected by either. Apparent senescence was delayed by depodding. Both apparent and functional senescence were accelerated by leaf removal.

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