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Heating energy savings potential from retrofitting old apartments with an advanced double-skin façade

Yeo Beom YOON, Byeongmo SEO, Brian Baewon KOH, Soolyeon CHO

《能源前沿（英文）》 2020年 第14卷 第2期   页码 224-240 doi: 10.1007/s11708-020-0801-1

摘要： Apartments account for over 60% of total residential buildings and consume a significant portion of primary energy in South Korea. Various energy efficiency measures have been implemented for both new apartment constructions and existing apartment retrofits. Old apartment structures have poor thermal performances, resulting in a high energy consumption. The South Korean government initiated retrofitting projects to improve the energy efficiency in old apartments. Apartment owners typically replace old windows with high-performance windows; however, there is still a demand for better and more innovative retrofit methods for a highly improved energy efficiency. This paper proposes an advanced double-skin façade (DSF) system to replace existing balcony windows in old apartments. Considering the cold climate conditions of Seoul, South Korea, it mainly discusses heating energy savings. Three case models were developed: Base-Case with existing apartment, Case-1 with typical retrofitting, and Case-2 with the proposed DSF system. The EnergyPlus simulation program was used to develop simulation models for a floor radiant heating system. A typical gas boiler was selected for low-temperature radiant system modeling. The air flow network method was used to model the proposed DSF system. Five heating months, i.e., November to March, and one representative day, i.e., January 24, were selected for detailed analysis. The main heat loss areas consist of windows, walls, and infiltration. The results reveal that the apartment with the DSF retrofit saves 38.8% on the annual heating energy compared to the Base-Case and 35.2% compared to Case-1.

关键词： double-skin façade     retrofitting     high-rise apartment     heating energy     building simulation    

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Seismic retrofitting of severely damaged RC connections made with recycled concrete using CFRP sheets

Yasmin MURAD, Wassel AL BODOUR, Ahmed ASHTEYAT

《结构与土木工程前沿（英文）》 2020年 第14卷 第2期   页码 554-568 doi: 10.1007/s11709-020-0613-8

摘要： An experimental and numerical program is carried out in this research to investigate the influence of CFRP sheets on the cyclic behavior of unconfined connections made with recycled concrete. Cement is partially replaced by silica fume, iron filling and pulverised fuel ash using two different percentages: 15% and 20%. Each specimen is partially loaded at the first stage and then specimens are repaired using CFRP sheets. The repaired specimens are then laterally loaded until failure. In addition, a finite element model is built in ABAQUS and verified using the experimental results. The experimental results have shown that the repaired specimens have regained almost double the capacity of the un-repaired specimens and hence the adopted repair configuration is recommended for retrofitting seismically vulnerable RC connections. Increasing cement replacement percentage by silica fume, fuel ash or iron filling from 15% to 20% has reduced joint carrying capacity and weakened the joint. It is recommended using 15% pulverised fuel ash or silica fume as cement partial replacement to enhance the strength and ultimate drift of beam-column joints under cyclic loading. Iron filling concrete is also recommended but the enhancement is relatively less than that found with pulverised fuel ash concrete and silica fume concrete.

关键词： retrofitting     CFRP sheets     recycled concrete     pulverised fuel ash     silica fume     cyclic     beam-column connections    

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An overview of the environmental finance policies in China: retrofitting an integrated mechanism for

LI Wei,HU Mengze

《环境科学与工程前沿（英文）》 2014年 第8卷 第3期   页码 316-328 doi: 10.1007/s11783-014-0625-5

摘要： Considering the significant roles of the policies in developing environmental finance, an overview is conducted on the environmental finance policies (EFPs) in China. This paper analyzed the definition, scope, evolution and main instruments of EFPs. The implementation progress of financial activities on each instrument are investigated respectively. Then the experiences learned from and failures discovered in the development of the EFPs are discussed well recommendations for further improvement of the EFPs and their implementation are provided. Our study found that the EFPs have been established in China after a four-phase evolution since the early 1980s. The policies have played a critical role in leading to a rapid development in environmental finance by involving more financial instruments to accomplish the objective-led environmental plans. Driven by the policies, the new green credit (GC), green security (GS), and green insurance (GI) instruments have been phased in as supplements to the conventional command and control approaches to improve the environmental governance of financial activities and pollution sources. However, the market mechanism of financial institution is limited due to their defensive and incapable performance on implementation some of EFP instruments. To further strengthen the effectiveness of EFPs in facilitating environmental management, recommendations are made mainly on the aspects including developing more specific policy guidelines, enhancing information sharing and disclosure, providing sufficient economic incentives, establishing environmental liabilities with financial activities, and involving issues related to climate change, and biodiversity and ecosystem service.

关键词： environmental finance policy     integrated mechanism     phased evolution     implementation progress     financial institution     environmental management    

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Seismic safety evaluation methodology for masonry building and retrofitting using splint and bandage

Pravin Kumar Venkat Rao PADALU; Yogendra SINGH

《结构与土木工程前沿（英文）》 2022年 第16卷 第4期   页码 478-505 doi: 10.1007/s11709-022-0817-1

摘要： The paper presents a seismic safety assessment of unreinforced masonry (URM) building using two approaches. The first approach uses the ‘Pier Analysis’ method, based on the concept of equivalent lateral stiffness, where in-plane and out-of-plane actions are considered independently. The second approach is developed with the program SAP2000, where the linear response is evaluated using continuum ‘finite element modelling’ (FEM). Both methods are compared to evaluate the safety of wall piers and the differences in the outcomes under combined gravitational and lateral seismic forces. The analysis results showed that few wall elements are unsafe in in-plane and out-of-plane tension. It is also observed that the pier analysis method is conservative compared to FEM, but can be used as a simplified and quick tool in design offices for safety assessment, with reasonable accuracy. To safeguard the URM wall piers under lateral loads, a retrofitting technique is adopted by providing vertical and horizontal belts called splints and bandages, respectively, using welded wire mesh (WWM) reinforcement. The study using the ‘Pier Analysis’ shows that the lateral load capacity of unsafe URM piers can be enhanced up to 3.67 times and made safe using the applied retrofitting technique. Further, the retrofitting design methodology and recommendations for application procedures to on-site URM buildings are discussed in detail.

关键词： unreinforced masonry     seismic in-plane and out-of-plane forces     pier analysis     finite element modelling     splint and bandage technique with wire mesh    

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Innovative seismic retrofitting strategy of added stories isolation system

Min-Ho CHEY, J. Geoffrey CHASE, John B. MANDER, Athol J. CARR

《结构与土木工程前沿（英文）》 2013年 第7卷 第1期   页码 13-23 doi: 10.1007/s11709-013-0195-9

摘要： The seismic performance of “added stories isolation” (ASI) systems are investigated for 12-story moment resisting frames. The newly added and isolated upper stories on the top of the existing structure are rolled to act as a large tuned mass damper (TMD) to overcome the limitation of the size of tuned mass, resulting to “12+2” and “12+4” stories building configurations. The isolation layer, as a core design strategy, is optimally designed based on optimal TMD design principle, entailing the insertion of passive flexible laminated rubber bearings to segregate two or four upper stories from a conventionally constructed lower superstructure system. Statistical performance metrics are presented for 30 earthquake records from the 3 suites of the SAC project. Time history analyses are used to compute various response performances and reduction factors across a wide range of seismic hazard intensities. Results show that ASI systems can effectively manage seismic response for multi-degree-of freedom (MDOF) systems across a broader range of ground motions without requiring burdensome extra mass. Specific results include the identification of differences in the number of added story by which the suggested isolation systems remove energy.

关键词： added stories     seismic isolation     tuned mass damper     parametric optimization     statistical method    

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A multi-objective design method for seismic retrofitting of existing reinforced concrete frames using

Yue CHEN; Rong XU; Hao WU; Tao SHENG

《结构与土木工程前沿（英文）》 2022年 第16卷 第9期   页码 1089-1103 doi: 10.1007/s11709-022-0851-z

摘要： Over the past several decades, a variety of technical ways have been developed in seismic retrofitting of existing reinforced concrete frames (RFs). Among them, pin-supported rocking walls (PWs) have received much attentions to researchers recently. However, it is still a challenge that how to determine the stiffness demand of PWs and assign the value of the drift concentration factor (DCF) for entire systems rationally and efficiently. In this paper, a design method has been exploited for seismic retrofitting of existing RFs using PWs (RF-PWs) via a multi-objective evolutionary algorithm. Then, the method has been investigated and verified through a practical project. Finally, a parametric analysis was executed to exhibit the strengths and working mechanism of the multi-objective design method. To sum up, the findings of this investigation show that the method furnished in this paper is feasible, functional and can provide adequate information for determining the stiffness demand and the value of the DCF for PWs. Furthermore, it can be applied for the preliminary design of these kinds of structures.

关键词： pin-supported rocking wall     reinforced concrete frame     seismic retrofit     stiffness demand     drift concentration factor     multi-objective design     genetic algorithm     Pareto optimal solution    

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Investigation on a mitigation scheme to resist the progressive collapse of reinforced concrete buildings

Iman TABAEYE IZADI, Abdolrasoul RANJBARAN

《结构与土木工程前沿（英文）》 2012年 第6卷 第4期   页码 421-430 doi: 10.1007/s11709-012-0181-7

摘要： This study presents the investigation of the approach which was presented by Thaer M. Saeed Alrudaini to provide the alternate load path to redistribute residual loads and preventing from the potential progressive collapse of RC buildings. It was proposed to transfer the residual loads upwards above the failed column of RC buildings by vertical cables hanged at the top to a hat steel braced frame seated on top of the building which in turn redistributes the residual loads to the adjacent columns. In this study a ten-storey regular structural building has been considered to investigate progressive collapse potential. Structural design is based on ACI 318-08 concrete building code for special RC frames and the nonlinear dynamic analysis is carried out using SAP2000 software, following UFC4-023-03 document. Nine independent failure scenarios are adopted in the investigation, including six external removal cases in different floors and three removal cases in the first floor. A new detail is proposed by using barrel and wedge to improve residual forces transfer to the cables after removal of the columns. Simulation results show that progressive collapse of building that resulted from potential failure of columns located in floors can be efficiently resisted by using this method.

关键词： prevent progressive collapse     alternate load path     reinforced concrete buildings     nonlinear dynamic     retrofitting     cable     steel hat braced frame     barrel and wedge    

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Performance of insulated FRP-strengthened concrete flexural members under fire conditions

Pratik P. BHATT, Venkatesh K. R. KODUR, Anuj M. SHAKYA, Tarek ALKHRDAJI

《结构与土木工程前沿（英文）》 2021年 第15卷 第1期   页码 177-193 doi: 10.1007/s11709-021-0714-z

摘要： This paper presents the results of fire resistance tests on carbon fiber-reinforced polymer (CFRP) strengthened concrete flexural members, i.e., T-beams and slabs. The strengthened members were protected with fire insulation and tested under the combined effects of thermal and structural loading. The variables considered in the tests include the applied load level, extent of strengthening, and thickness of the fire insulation applied to the beams and slabs. Furthermore, a previously developed numerical model was validated against the data generated from the fire tests; subsequently, it was utilized to undertake a case study. Results from fire tests and numerical studies indicate that owing to the protection provided by the fire insulation, the insulated CFRP-strengthened beams and slabs can withstand four and three hours of standard fire exposure, respectively, under service load conditions. The insulation layer impedes the temperature rise in the member; therefore, the CFRP–concrete composite action remains active for a longer duration and the steel reinforcement temperature remains below 400°C, which in turn enhances the capacity of the beams and slabs.

关键词： concrete beams     concrete slabs     carbon fiber-reinforced polymers     fire resistance     FRP strengthening     repair     retrofitting    

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标题 作者 时间 类型 操作

Heating energy savings potential from retrofitting old apartments with an advanced double-skin façade

Yeo Beom YOON, Byeongmo SEO, Brian Baewon KOH, Soolyeon CHO

期刊论文

Seismic retrofitting of severely damaged RC connections made with recycled concrete using CFRP sheets

Yasmin MURAD, Wassel AL BODOUR, Ahmed ASHTEYAT

期刊论文

An overview of the environmental finance policies in China: retrofitting an integrated mechanism for

LI Wei,HU Mengze

期刊论文

Seismic safety evaluation methodology for masonry building and retrofitting using splint and bandage

Pravin Kumar Venkat Rao PADALU; Yogendra SINGH

期刊论文

Innovative seismic retrofitting strategy of added stories isolation system

Min-Ho CHEY, J. Geoffrey CHASE, John B. MANDER, Athol J. CARR

期刊论文

A multi-objective design method for seismic retrofitting of existing reinforced concrete frames using

Yue CHEN; Rong XU; Hao WU; Tao SHENG

期刊论文

Investigation on a mitigation scheme to resist the progressive collapse of reinforced concrete buildings

Iman TABAEYE IZADI, Abdolrasoul RANJBARAN

期刊论文

Performance of insulated FRP-strengthened concrete flexural members under fire conditions

Pratik P. BHATT, Venkatesh K. R. KODUR, Anuj M. SHAKYA, Tarek ALKHRDAJI

期刊论文