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Shear strength prediction of concrete-encased steel beams based on compatible truss-arch model

  • Xue, Yicong;Shang, Chongxin;Yang, Yong;Yu, Yunlong;Wang, Zhanjie
    • Steel and Composite Structures
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    • 제43권6호
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    • pp.785-796
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    • 2022
  • Concrete-encased steel (CES) beam, in which structural steel is encased in a reinforced concrete (RC) section, is widely applied in high-rise buildings as transfer beams due to its high load-carrying capacity, great stiffness, and good durability. However, these CES beams are prone to shear failure because of the low shear span-to-depth ratio and the heavy load. Due to the high load-carrying capacity and the brittle failure process of the shear failure, the accurate strength prediction of CES beams significantly influences the assessment of structural safety. In current design codes, design formulas for predicting the shear strength of CES beams are based on the so-called "superposition method". This method indicates that the shear strength of CES beams can be obtained by superposing the shear strengths of the RC part and the steel shape. Nevertheless, in some cases, this method yields errors on the unsafe side because the shear strengths of these two parts cannot be achieved simultaneously. This paper clarifies the conditions at which the superposition method does not hold true, and the shear strength of CES beams is investigated using a compatible truss-arch model. Considering the deformation compatibility between the steel shape and the RC part, the method to obtain the shear strength of CES beams is proposed. Finally, the proposed model is compared with other calculation methods from codes AISC 360 (USA, North America), Eurocode 4 (Europe), YB 9082 (China, Asia), JGJ 138 (China, Asia), and AS/NZS 2327 (Australia/New Zealand, Oceania) using the available test data consisting of 45 CES beams. The results indicate that the proposed model can predict the shear strength of CES beams with sufficient accuracy and safety. Without considering the deformation compatibility, the calculation methods from the codes AISC 360, Eurocode 4, YB 9082, JGJ 138, and AS/NZS 2327 lead to excessively conservative or unsafe predictions.

Research on the development law of karst fissures and groundwater characteristic in Xintian County

  • Xin, Zhou;Tengfei, Yao;Can, Wang;Jian, Ou;Pengfei, Zheng;Kaihong, Chen;Xiting, Long
    • Membrane and Water Treatment
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    • 제13권6호
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    • pp.303-312
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    • 2022
  • The natural hydrology and geological conditions of Xintian County was investigated, the development law of regional karst fissures was studied, the groundwater was collected and tested through a large-scale collection of groundwater to obtain the change law of chemical characteristics and water quality characteristics of groundwater, and the water quality evaluation was carried out for the regional karst groundwater in this paper. The results show that, the whole area is dominated by carbonate rock distribution areas, and the distribution of water systems is relatively developed. The strata are distributed from the Lower Paleozoic Cambrian to the Cenozoic Quaternary, and contain multiple first-order folds. The regional karst dynamic action is strong, and many tunnels or caves of different scales were shown, which are conducive to the enrichment of groundwater. Karst groundwater is neutral and alkaline water, the water is clear and transparent with good taste, and meets the national drinking water hygiene standards. The content of toxic trace elements and fluoride in the water source is generally lower than the limit value specified by the national standard and the accumulated toxic heavy metals is never found. The overall water quality is of good quality and suitable for the development and utilization of various purposes.

Shaking table test and horizontal torsional vibration response analysis of column-supported vertical silo group silo structure

  • Li, Xuesen;Ding, Yonggang;Xu, Qikeng
    • Advances in concrete construction
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    • 제12권5호
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    • pp.377-389
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    • 2021
  • Reinforced concrete vertical silos are universal structures that store large amounts of granular materials. Due to the asymmetric structure, heavy load, uneven storage material distribution, and the difference between the storage volume and the storage material bulk density, the corresponding earthquake is very complicated. Some scholars have proposed the calculation method of horizontal forces on reinforced concrete vertical silos under the action of earthquakes. Without considering the effect of torsional effect, this article aims to reveal the expansion factor of the silo group considering the torsional effect through experiments. Through two-way seismic simulation shaking table tests on reinforced concrete column-supported group silo structures, the basic dynamic characteristics of the structure under earthquake are obtained. Taking into account the torsional response, the structure has three types of storage: empty, half and full. A comprehensive analysis of the internal force conditions under the material conditions shows that: the different positions of the group bin model are different, the side bin displacement produces a displacement difference, and a torsional effect occurs; as the mass of the material increases, the structure's natural vibration frequency decreases and the damping ratio Increase; it shows that the storage material plays a role in reducing energy consumption of the model structure, and the contribution value is related to the stiffness difference in different directions of the model itself, providing data reference for other researchers; analyzing and calculating the model stiffness and calculating the internal force of the earthquake. As the horizontal side shift increases in the later period, the torsional effect of the group silo increases, and the shear force at the bottom of the column increases. It is recommended to consider the effect of the torsional effect, and the increase factor of the torsional effect is about 1.15. It can provide a reference for the structural safety design of column-supported silos.

Effects of heavy metal lead on differential cell counts in occupationally-exposed subjects from Saudi Arabia

  • Abjal P. Shaik;Abbas H. Alsaeed;Asma S. Shaik;Abdullah A. Alyousef;Vamsee K. Bammidi;Kiranmaye Sampathirao
    • Advances in environmental research
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    • 제11권1호
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    • pp.31-38
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    • 2022
  • The current observational epidemiological study analyzed blood lead levels (BLLs) in occupationally exposed workers from Riyadh region, Saudi Arabia and correlated them with the alterations in the differential cell populations of the WBC panel (lymphocytes [Lym %], mixed [Mid %] cells, and neutrophils [Neu %]). In addition, we examined the effect of confounding factors and their relation to BLLs. BLLs were estimated using the LeadCare II analyzer and hematological parameters using the ADVIA 120 analyser. An inferential analysis was conducted to detect association between the observations and the subjects' clinical characateristics. A total of 132 male subjects were included in the final analyses. Based on CDC guidelines, the subjects were categorized as Group I (BLL <10 ㎍/dL; n=118) or Group II (BLL >10 ㎍/dL; n=14) with average BLLs of 4.4 ㎍/dL and 18.1 ㎍/dL, respectively (p <0.0001). The percentages of Mid cells (p <0.0001) and neutrophils (p=0.048), were significantly altered in subjects with High BLL. A regression analysis indicated that subjects > 50 years of age had significantly higher BLLs (53.2 ㎍/dL) than younger age sub-groups (p <0.0001). Age, education, and profession were significant predictors for lead toxicity. Pb exposure is a major public health issue in Saudi Arabia and calls for further investigations on the cellular and molecular effects on hematological system.

Towards attaining efficient management of berth maintenance in Saudi Arabian Industrial Ports

  • Mohammed E. Shaawat;Abdullah Binomar;Abdulaziz S. Almohassen;Khalid Saqer. Alotaibi;Mahmoud Sodangi;Ahmad Aftab
    • Structural Monitoring and Maintenance
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    • 제10권1호
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    • pp.25-42
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    • 2023
  • Despite the significance of ports as critical economic infrastructure, the berth facilities usually deteriorate due to heavy loading, unloading, aging, environmental weather conditions, marine growths, and lack of efficient maintenance management. Marine berths require proactive maintenance management to limit deterioration and defects as no berth facility is maintenance-free. Thus, delay in carrying out maintenance work for the marine berths can be devastating to the operational process involving ship entry, loading, and unloading operations. The aim of this research is to coordinate both operations work, and maintenance works that take place inside the berth of a local industrial port in Saudi Arabia, by developing a novel framework that integrates both works without affecting the efficiency and functionality of the berth. The study focused on defining the operational process of the port and identifying the elements with direct and indirect effects. In addition to determining the priority for the entry of ships inside the berth, it also identified the factors involved in designing a framework that included maintenance work as a component of the monthly berth occupancy schedule. By applying a mathematical model, a framework was established, which includes all the important elements of the process. As a result of the mathematical method formulation process, a database was designed that organizes and coordinates the operations of all berths within the port. This creates time to carry out the required maintenance work monthly as well as ease of coordination with the contractors responsible for the implementation of those works.

Improvement of the amplification gain for a propulsion drives of an electric vehicle with sensor voltage and mechanical speed control

  • Negadi, Karim;Boudiaf, Mohamed;Araria, Rabah;Hadji, Lazreg
    • Smart Structures and Systems
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    • 제29권5호
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    • pp.661-675
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    • 2022
  • In this paper, an electric vehicle drives with efficient control and low cost hardware using four quadrant DC converter with Permanent Magnet Direct Current (PMDC) motor fed by DC boost converter is presented. The main idea of this work is to improve the energy efficiency of the conversion chain of an electric vehicle by inserting a boost converter between the battery and the four quadrant-DC motor chopper assembly. Consequently, this method makes it possible to maintain the amplification gain of the 4 quadrant chopper constant regardless of the battery voltage drop and even in the presence of a fault in the battery. One of the most important control problems is control under heavy uncertainty conditions. The higher order sliding mode control technique is introduced for the adjustment of DC bus voltage and mechanical motor speed. To implement the proposed approach in the automotive field, experimental tests were carried out. The performances obtained show the usefulness of this system for a better energy management of an electric vehicle and an ideal control under different operating conditions and constraints, mostly at nominal operation, in the presence of a load torque, when reversing the direction of rotation of the motor speed and even in case of battery chamber failure. The whole system has been tested experimentally and its performance has been analyzed.

Postmodern Animality and Spectrality: Ted Hughes's Wodwo and Crow

  • Park, Jung Pil
    • 영어영문학
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    • 제58권6호
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    • pp.1143-1165
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    • 2012
  • Tinted with ontological concern, Ted Hughes passes through an existential climate, eventually confirms death( or nothingness) as the new foundation of his poetry, and explores the various paradoxical effects of nothingness. Nihilism, fraught with rather negative and traumatic themes such as death, melancholy, and despair can, however, generate being (even in multiple modes), animalistic vitality, and insubstantial specters. Among these new functions of nothingness animality and spectrality are the most notable in Hughes's poetry. A considerable number of animals and bioorganisms that Hughes introduces exhibit the enormous energy derived from the dignity of death, from subversive challenges against the established hierarchy, and from new and dynamic multifaceted sources of nothingness. In other words, Hughes's animals, yield surplus power beyond themselves, as if they are demi-gods; in short, they feature the sublime as unidentified terrifying effects of nothingness. In a sense, animality means allowing some level of violence without legal sanction. Hughes inaugurates this kind of all bigotry-eradicating violence and attempts to subvert higher beings such as humans and gods, and existing doctrines: thrushes rise up against the animal and human worlds; a rush of ghostly crabs at night press through the human world. Hughes also resists the highest being, God, employing the technique of rewriting God's theology. Dirty, anomalous crows attack, subvert, and dismember the delicate, indurate, and thorough system of logos. Hughes, of course, does not place the animals merely in lofty regard, aware of the ulterior deprivation of the sublime animality, the trace of existential negativity. Thus, a seemingly omnipotent crow can become a mere beggar guzzling ice cream from the garbage bin on the beach. In addition, the violent and dignified aspects of nothingness can be transformed to reveal the thin and trivial traits as unreliable specters. Dark, heavy, and terrible nullity lessens its own volume and mass, and exposes the airy waves of shadows or specters. However, owing to nullity's untraceable track, the scarcity and unfamiliarity of the phantoms inversely display their foreign gigantic effects such as fantasy and violence.

Seismic behavior of coupled wall structure with innovative quickly replaceable coupling beams

  • Li, Yong;Yu, Haifeng;Liang, Xiaoyong;Yu, Jianjun;Li, Pengcheng;Wang, Wei;Wang, Qizhi
    • Steel and Composite Structures
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    • 제45권2호
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    • pp.293-303
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    • 2022
  • In order to improve the seismic resilience of coupled wall structure, coupling beam with fuse has been developed to reduce the post-earthquake damage. However, the fuses often have a build-up I-shaped section and are relatively heavy to be replaced. Moreover, the fuse and the beam segments are usually connected by bolts and it is time-consuming to replace the damaged fuse. For reducing the repair time and cost, a novel quickly replaceable coupling beam with buckling-restrained energy dissipaters is developed. The fuse of the proposed coupling beam consists of two chord members and bar-typed energy dissipaters placed at the corners of the fuse. In this way, the weight of the energy dissipater can be greatly reduced. The energy dissipaters and the chords are connected with hinge and it is convenient to take down the damaged energy dissipater. The influence of ratio of the length of coupling beam to the length of fuse on the seismic performance of the structure is also studied. The seismic performance of the coupled wall system with the proposed coupling beam is compared with the system with reinforced concrete coupling beams. Results indicated that the weight and post-earthquake repair cost of the proposed fuse can be reduced compared with the typical I-shaped fuse. With the increase of the ratio of the beam length to the fuse length, the interstory drift of the structure is reduced while the residual fuse chord rotation is increased.

The effect of rectangular and T-shaped stiffeners on the seismic performance of CFDT columns

  • Mojtaba Labibzadeh;Keyvan Parsa;Farhad Hosseinlou;Majid Khayat
    • Earthquakes and Structures
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    • 제27권3호
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    • pp.191-207
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    • 2024
  • Due to the many advantages of concrete-filled double steel tube (CFDT) columns, they are highly recommended for use in heavy-load structures such as bridges, subway stations, and high-rise buildings. This study was carried out with the aim of numerically investigating and comparing the performance of CFDT columns under cyclic and seismic loads and providing innovative strengthening methods for CFDT columns. Hollow circular steel sections have been used for internal and external tubes. To make the circular CFDT columns stronger against seismic loads, stiffeners with different shapes (rectangular and T-shaped sheets) have been welded to the outside and inside tubes. The validated finite element (FE) model of the ABAQUS program is used to look into the behavior of CFDT columns numerically. Two frames of 10 and 20 floors with strengthened CFDT columns were modeled. The results showed that the use of stiffeners in the CFDT column has a significant effect on seismic performance, so that the maximum lateral load of the column is increased up to 32.74% under the effect of cyclic load. Also, the results revealed that the use of stiffeners in the columns of moderate and high-rise building frames causes a significant increase in the shear of the base and consequently the stiffness. Among the other important results that followed, it reduced the drift of floors and increased energy absorption.

신문고 제도에 대한 몇 가지 쟁점: 기원과 운영, 기능.제도의 변천을 중심으로 (A Study on the Shinmoongo System: Issues of the Origin and Changes of Function and Institution)

  • 김영주
    • 한국언론정보학보
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    • 제39권
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    • pp.250-283
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    • 2007
  • 이 논문의 목적은 조선시대 '청원 상소 고발의 최후 수단'으로 알려진 신문고 제도의 기원, 기능과 운영의 변천, 그리고 대체기능을 수행했던 격쟁 제도의 배경과 그 부침에 대해 몇 가지 쟁점 중심으로 살펴보는 데 있다. 조선시대 군주와 신하들은 신문고 제도의 기원을 이론적 차원에서 하은주 삼대(三代)에 설치되었다는 '감간지고(敢諫之鼓)'로 보았지만, 실천적 차원에서 주자(朱子)가 활동했던 송나라의 태조가 설치하였다는 등문고(登聞鼓)라고 인식하였다. 그러나, 역사적 사실은 후한 때 이미 '간고'가 설치되어 있었으며 위진남북조 시대의 진조(晉朝)부터 시작하여 당 송을 거쳐 명 청에 이르기까지 지속적으로 '등문고'를 설치 운영한 것이다. 신문고 제도는 태종 때 개인적 상소사건 사회적 청원사건 국가적 고발사건 등을 다양하게 상달하는 '언론제도'였지만, 세종 2년부터 개인적 원억문제를 주로 해결하는 '사법제도'로 전락하였다. 원래의 설치 목적은 '억울한 일이 있으나 고할 데 없는 일반백성'들에게 그들의 하정을 상달하기 위한 것이었지만, 건국 초기 무질서한 가전상언(駕前上言)이나 월소직정의 폐단을 방지하기 위한 제도적 장치로 활용되었다. 일부 사대부 계급들의 사적 이익을 도모하는 도구로 악용되기도 하고 관찰사나 수령의 권력남용을 견제하는 역할을 수행하였던 신문고 제도는, 수도의 궁궐에 위치하고 여러 단계마다 각각 글로 올려야 되며, 위법 격고자에 대한 처벌도 과중하고 신분제 아래에서 상관에 관계되면 신문고 사용이 통제되는 까닭에 일반 백성들이나 천민들이 이용하기는 어려운 일이었다. 신문고 제도의 폐지 후 탄생한 격쟁 제도는 중국에 없는 우리나라 고유한 언로양식으로, 세조 14년에 '불법 관리에 대한 고소'가 허용되자 관사의 노복들이 내부 고발자가 되어 고소활동의 한 방편으로 마련되었다. 격쟁 제도의 설립 초기는 개인적 원억문제 해결을 위한 것이 아니었지만, 나중에 결국 신문고 제도의 대안적 장치로 그 역할을 수행하게 되었다. 신문고 제도는 조선시대에 발달된 합법적 언론제도뿐만 아니라 비합법적 반(半)합법적 언론제도 예컨대, 통문(通文)이나 격문(檄文), 등장(等狀), 격쟁(擊錚), 가전상언(駕前上言), 규혼, 익명서(匿名書) 등과 함께 적절하게 연동함으로써 결과적으로 왕권을 강화하고 신권을 약화시키는 효과를 얻을 수 있었다.

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