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On the delay factors of the private construction projects in Medan city

IOP Conference Series: Earth and Environmental Science 2018年第1期126卷

作者： A. Perwira Mulia Tarigan Subroto Teaching Staff Post Graduate Study Program of Civil Engineering Universitas Sumatera Utara Former Graduate Student Post Graduate Study Program of Civil Engineering Universitas Sumatera Utara

The delay in construction projects undertaken by contractors is impeding the economic growth of a region. Medan city which is one of the big cities in Indonesia is suffering from it. This study aims to identify the dominant factors causing delays in construction projects conducted by private contractors. The interview method with questionnaires is used to involve 20 contractors, 10 consultants, and 10 owner representatives in the study. From the 45 identified factors causing delays, the highest ranking is the change of work demand by the project owners with 71.84% importance index.

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A feasibility study of recycling of construction and demolition waste for structural purposes

Journal of Solid Waste Technology and Management

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Journal of Solid Waste Technology and Management 2013年第3期39卷 204-213页

作者： Mariano, Leila Seleme Da Costa, Marienne Do Rocio De Mello Maron Braga, Maria Cristina Borba Brasilian Air Force Integrated Air Traffic and Control Center - CINDACTA II Brazil Parana Federal University Department of Civil Engineering Civil Engineering Post-Graduate Program Brazil Parana Federal University Department of Hydraulics and Sanitation Water Resources and Environmental Engineering Post-Graduate Program Brazil Universidade Federal do Paraná Setor de Tecnologia Centro Politécnico - Jardim das Américas CxP 19011 81531-980 Curitiba - Paraná Brazil

The environmental problems related to construction and demolition waste involve their final dis-posal and the use of raw materials. The main goal of this research was to manage on site con-struction and demolition waste and generate concrete for structural purposes by processing concrete and mortar wastes. A Construction and Demolition Waste Management Plan (CDWMP) was developed for this study and applied by means of the implementation of recy-cling procedures. This plan included quantifying wastes and analyzing their generation. The concrete and mortar wastes were separated for recycling to produce concrete in which these wastes, respectively, replaced fractions of coarse aggregate (crushed stone) and fine aggre-gate (sand). Tests were carried out to characterize the resulting concrete and the aggregates used. The strength of the concrete generated varied from 6 MPa to 21.4 MPa, for the same mixture. It was observed that structural concretes can be produced using recycled aggregates, however this cost is higher compared to that of concrete produced with conventional aggre-gates. It was also concluded that despite the cost of concrete production, there were environmental and economic advantages to performing and applying the CDWMP to this specific con-struction site. Copyright © 2013 Widener University.

关键词： Recycling

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Assessing the performance of eggshell ash as a sustainable bitumen modifier

Transportation Engineering

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Transportation engineering 2023年 13卷

作者： Syammaun, Tamalkhani Husaini Abdullah Isya, Muhammad Rachman, Firmansyah Doctoral Program School of Engineering Post Graduate Program Universitas Syiah Kuala Banda Aceh23111 Indonesia Department of Civil Engineering Universitas Muhammadiyah Aceh Banda Aceh23123 Indonesia Department of Mechanical Engineering Universitas Syiah Kuala Banda Aceh23111 Indonesia Department of Civil Engineering Universitas Syiah Kuala Banda Aceh23111 Indonesia

The disposal of eggshells in landfills presents an ongoing global environmental issue that demands immediate attention. However, a promising solution lies in utilizing eggshells as modifiers in bitumen binders, offering a sustainable approach to alleviating this burden. This study focuses on crushing eggshells to produce eggshell ash, which is then explored as a potential modifier in bitumen binders. The objective is to evaluate the properties of modified bitumen binders incorporating eggshell waste sourced from the food industry and examine their application in bitumen engineering. The optimal weight percentage of eggshell ash in the bitumen is determined, considering four levels (5, 7, 10 and 12%) and two heating temperatures (100 and 200 °C). Several tests are conducted to comprehensively evaluate the eggshell ash, including SEM-EDS and FTIR analyses, providing valuable technical insights into its properties. Additionally, DSR measurements are employed to analyze the characteristics of the bitumen incorporating eggshell ash. The primary oxide group present in the eggshell ash is CaCO3. Notably, higher concentrations of eggshell ash enhance the resistance of bitumen binders to high temperatures, as indicated by the penetration index results. Furthermore, DSR testing reveals that adding eggshell ash increases the rigidity of the bitumen binders, resulting in improved resistance to deformation. © 2023 The Author(s)

关键词： Binders

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The influence of earthquake force directions on building construction in Lombok Island: a case study of Pandanduri dam in East Lombok

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IOP Conference Series: Earth and Environmental Science 2020年第1期413卷

作者： F Afrizal D S Agustawijaya A Lestari Post-Graduate Study Program in Civil Engineering University of Mataram Indonesia.

Lombok Island is one of the regions in Indonesia that has a relatively high risk of earthquakes due to being flanked by two earthquake sources, namely from the south in the form of Indo-Australian plate thrusting (subduction mega-thrust) and north there is a north arc pressure (Flores thrust). Pandanduri Dam is located in the direction of the earthquake force N 171° E. This study aims to determine changes in dam planning using earthquake force calculations from SNI 1726-2002 to SNI 1726-2012 and the effect of the direction of earthquake strength on dam stability. The analysis results show that earthquake risk in Lombok Island is 0.34 g and 0.42 g for the possibility of exceeding 10% and 2% in 50 years. SNI changes in earthquake force calculations have decreased by 26% for 500 years and an increase of 10% for 2500 years. The percentage of the earthquake force directions is not known to be greater than the percentage the earthquake force directions known that N 171°E is influenced by the angle produced by the earthquake direction N 171° E which is 0.094° for the main force direction of the dam and 89,906° for the direction perpendicular to the dam.

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Flood handling with priority scale determination in Samarinda Seberang from East Kalimantan Province Indonesia

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IOP Conference Series: Materials Science and engineering 2020年第1期885卷

作者： SSN. Banjarsanti P. Kukuh Theta Margaritifera Civil Engineering Study Program Samarinda State Polytechnic Civil Engineering Post-graduate Program Gunadarma University Depok

Handling of flooding caused by changes in land use often causes changes and problems in the magnitude of runoff coefficient, discharge, water level, and drainage channel dimensions, as happened in Samarinda Seberang. The purpose of this study was to plan a drainage channel according to the priority scale using the Rational Modification Method as a Hydrological Analysis and Manning as a Hydraulics Analysis. Handling method is carried out in the form of structuring and planning the drainage system according to priority scale based on inundation parameters, economic studies, social and transportation disturbances, loss of housing areas, and property rights. The higher the criteria for handling the area is a priority. The results showed that the highest priority scale (610) was obtained on Cipto Mangunkusumo street, and the lowest priority scale (220) was at Bung Tomo street and Hasanuddin street. Cipto Mangunkusumo street as the highest priority scale will be planned for the first priority drainage channel with a design flood discharge in the 10 year return period (Q) 7.79 m3 / sec, the drainage channel dimension consists of the basic width of the channel (b) 0.77 m ∼ 0.80 m, channel peak width (T) 3.30 m, channel depth (h) 1.925 m, watch height (f) 0.6 m, total depth 2.52 m, and slope of channel wall (m) 1: 1).

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Assessment of Stainless Steel Tubular T-joints Under Chord Sidewall Failure Mode by a Semi-analytical Formulation

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ce/papers 2022年第4期5卷 574-583页

作者： Nogueira, Mateus M. de Lima, Luciano R. O. da S. Vellasco, Pedro C. G. Young, Ben PGECIV - Civil Engineering Post-Graduate Program UERJ – State University of Rio de Janeiro Brazil Structural Engineering Department UERJ – State University of Rio de Janeiro Brazil Department of Civil and Environmental Engineering The Hong Kong Polytechnic University Hong Kong

There are numerous benefits of tubular profiles that make them increasingly used in civil engineering. At the same time, stainless steel is a material with excellent properties and high corrosion resistance. However, stainless steel's high initial material cost has limited its use primarily to specialist and prestige applications, which makes it necessary to develop more accurate design rules for this material. When tubular profiles are used, it is necessary to assess the joint strengths, considering that they can fail by different mechanisms. The present work aims to develop a semi-analytical formulation to predict stainless steel tubular T-joint resistances. Joints with the brace-to-chord width ratio equal to 1 were considered in this study;therefore, the failure occurs in the chord sidewall. To assess the sidewall instability critical load, the exact stress fields were determined using Mathieu's theory, and then the Ritz energy method was applied. Considering that the joints are made of stainless steel, the next step is to transform the load found from linear to the non-linear regime. For that, a new formulation based on Ramberg-Osgood equations was developed. Finally, the results obtained from the proposed method were compared with the experimental results obtained by Feng and Young (2008) and the results from the main current standards and literature. It was observed that the proposed method presented satisfactory results, while the predictions from design codes were, in general, very conservative. © 2022 Ernst & Sohn GmbH.

关键词： Failure (mechanical)

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Numerical assessment of stainless steel tubular T-joints subjected to brace and chord axial forces

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ce/papers 2021年第2-4期4卷 2495-2503页

The utilisation of tubular sections in steel structures has increased significantly worldwide. The use of stainless steel provides several benefits for structures, including high corrosion resistance, durability, fire resistance and ease of maintenance. A significant issue in the design of tubular structures is the joints failure since they are highly susceptible to local failures that influence their actual overall behavior. The design rules of welded carbon steel tubular joints are available, such as Eurocode 3, part 1-8, NBR 16239, ISO 14346 and CIDECT guides. When stainless steel tubular joints are considered, the AS/NZS 4673 Australian/New Zealand Standard is the only available specification that can be used. An experimental and numerical analysis of these tubular joints are recommended since they enable a more accurate evaluation of their structural performance. Concerning these aspects, this work aims to investigate stainless steel tubular T-joints fabricated by SHS and RHS cold-formed profiles that focused on the effect of chord pre-loading. For this purpose, a numerical study based on finite element analysis was performed. The finite element model was developed and calibrated against experiments. The results were subsequently compared with the aforementioned design predictions. © 2021 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.

关键词： Finite element method

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Influence of recycled aggregate on the rheological behavior of cement mortar

Influence of recycled aggregate on the rheological behavior ...

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14th International Conference on Non-Conventional Materials and Technologies for Sustainable engineering, NOCMAT 2013

作者： Lima, Paulo Roberto Lopes Filho, Romildo Dias Toledo Da Fonseca Martins Gomes, Otávio 1Post-graduate Program of Civil and Environmental Engineering Department of Technology State University of Feira de Santana Av. Transnordestina S/N-Novo Horizonte Feira de Santana Bahia 44036-900 Brazil Civil Engineering Program/COPPE Federal University of Rio de Janeiro Rio de Janeiro Brazil Centre for Mineral Technology-CETEM Av. Pedro Calmon 900 21941-908 Rio de Janeiro Brazil University of Liege GeMMe Georesources and Geoimaging Sart Tilman B52 4000 Liege Belgium

ISBN: (纸本)9783037859810

In this work it was studied the influence of recycled fine aggregate obtained from construction and demolition waste (CDW) on the rheological properties of Portland cement mortars. The CDW was initially separate in their main constituents (mortar, ceramic and concrete debris) at the laboratory and then grinded separately to the sand size in order to generate more homogeneous fine aggregates. The characterization of the natural and recycled sands was carried out through physical tests, X-ray diffraction, scanning electron microscopy (SEM), and image analysis (shape and texture description parameters). A conventional mortar and three mortars containing recycled sands were produced with a sand/cement ratio of 4 and consistency index of 255±5 mm. The consistency was kept constant by ranging the water-cement ratio from 0.58 to 1.14. The rheological study was performed using a rotating viscometer to obtain torque-rotation ratio and to calculate the yield stress and plastic viscosity. The results indicate that the presence of recycled aggregate causes a lowering of both yield stress and plastic viscosity with respect to the mortar containing natural aggregate. © (2014) Trans Tech Publications, Switzerland.

关键词： Mortar

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An Investigation of Hydro-morphology Contributory Factors in Flooding and Sedimentation Problems on the Krueng Buloh River, Indonesia

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Open civil engineering Journal 2023年 17卷

作者： Listia, Vina Munirwansyah, Munirwansyah Azmeri, Azmeri Yulianur, Alfiansyah Doctoral Program School of Engineering Post Graduate Program Universitas Syiah Kuala Banda Aceh Darussalam 23111 Indonesia Department of Civil Engineering Faculty of Engineering Universitas Syiah Kuala Banda Aceh Darussalam 23111 Indonesia

Introduction: Process-based river hydrology and morphological analyses are infrequent, especially in developing countries. Climate change and the expected occurrence of major floods and erosion that could threaten the safety of nearby and downstream settlements, especially in areas that are very sensitive and affected by global warming, have made this kind of investigation necessary. Methods: The watershed of the River Krueng Buloh is prone to severe flooding, which has many social and economic effects on the villages nearby, such as the loss of crops and the destruction of buildings. However, the hydro-morphology and fluctuation of this river have not yet been studied. This research aims to determine which factors influence the stability of a river channel in the downstream region of the Krueng Buloh watershed following flooding or erosion. Results: To achieve this objective, field, and satellite-based observations of the hydro-morphology of a Krueng Buloh watershed have been performed. The investigation reveals that floods and sediment accumulation in the floodplain were triggered by excessive rainfall, the meandering of the river, and the riverbank soil type. Conclusion: The conclusions and methods given can be used to evaluate flooding and sedimentation in rivers for future operations to protect and preserve rivers. © 2023 Listia et al.

关键词： Erosion Flood Hydrology Morphology River Sedimentation Watershed

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Evaluation of the Performance of Different Damage Indicators in Railway Bridges

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Procedia engineering 2015年 114卷 746-753页

作者： Vinicius Alves Andreia Meixedo Diogo Ribeiro Rui Calçada Alexandre Cury Post-Graduate Program in Civil Engineering Federal University of Ouro Preto Ouro Preto Brazil Faculty of Engineering University of Porto Porto Portugal School of Engineering Polytechnic of Porto Porto Portugal Departament of Applied and Computational Mechanics Federal University of Juiz de Fora Juiz de Fora Brazil

This article describes a damage identification methodology based on a genetic algorithm and its application to the numerical model of a railway bridge. The identification method is based on an iterative process that in each iteration compares the values of the bridge's dynamic response for a test damage scenario with the response values for a reference damage scenario. The introduction of damage to the test numerical model is based on the modification of a preselected numerical parameter values. The genetic algorithm allows the identification of damage by minimizing the residue of an objective function constructed from the responses of the test and reference model, and based on the so-called damage indicators. In this study are defined and tested damage indicators based on modal parameters (frequencies and vibration modes) in parameters built from the modal parameters (modal curvatures and flexibility curvatures), and in dynamic responses under action of impulsive loads from frequency response functions (FRFs). The proposed methodology for identifying damage was tested based on a two-dimensional numerical finite element model of a railway bridge including the railway track. The results allowed evaluating the efficiency and reliability of the methodology and of the damage indicators which, in most situations, showed potential in the detection, location and quantification of the severity of the damage.

关键词： Damage identification iterative method genetic algorithm damage indicators railway bridges.

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