Adequacy of structural fire design in uncommon structures is conceptually ensured through cost-benefit analysis where the future costs are balanced against the benefits of safety investment.Cost-benefit analyses,howev...Adequacy of structural fire design in uncommon structures is conceptually ensured through cost-benefit analysis where the future costs are balanced against the benefits of safety investment.Cost-benefit analyses,however,are complicated and computationally challenging,and hence impractical for application to individual projects.To address this issue,design guidance proposes target reliability indices for normal design conditions,but no target reliability indices are defined for structural fire design.We revisit the background of the cost-optimization based approach underlying normal design target reliability indices then we extend this approach for the case of fire design of structures.We also propose a modified objective function for cost-optimization which simplifies the evaluation of target reliability indices and reduces the number of assumptions.The optimum safety level is expressed as a function of a new dimensionless variable named“Damage-to-investment indicator”(DII).The cost optimization approach is validated for the target reliability indices for normal design condition.The method is then applied for evaluating DII and the associated optimum reliability indices for fire-exposed structures.Two case studies are presented:(i)a one-way loaded reinforced concrete slab and(ii)a steel column under axial loading.This study thus provides a framework for deriving optimum(target)reliability index for structural fire design which can support the development of rational provisions in codes and standards.展开更多
On March 28,2025,an M_(w) 7.7 earthquake struck near Mandalay,Myanmar,producing intense ground shaking.Strong motion recorded at a station close to the fault indicated a peak ground acceleration of 1.066 g in the vert...On March 28,2025,an M_(w) 7.7 earthquake struck near Mandalay,Myanmar,producing intense ground shaking.Strong motion recorded at a station close to the fault indicated a peak ground acceleration of 1.066 g in the vertical direction and 0.631 g in the horizontal direction.The earthquake caused collapse or severe damage of numerous buildings,resulting in thousands of fatalities and injuries,as well as substantial economic losses.The authors participated in the post-earthquake emergency response as members of the China Search and Rescue Team.During the rescue operations,an investigation into the characteristics of collapsed structures was conducted and the stability of building debris was assessed to ensure the safety of rescue efforts.Subsequently,a rapid seismic safety assessment of affected structures was carried out,including nine city residential blocks,two hospitals,and two apartments.Preliminary analyses indicate that the main causes of structural failure were insufficient cross-sectional dimensions of beams and columns,inadequate stirrup reinforcement,and lack of structural redundancy.展开更多
The natural landscape in China exposes many existing RC buildings to aggressive environments.Such exposure can lead to deterioration in structural performance with regard to resisting events such as earthquakes.Corros...The natural landscape in China exposes many existing RC buildings to aggressive environments.Such exposure can lead to deterioration in structural performance with regard to resisting events such as earthquakes.Corrosion of embedded reinforcement is one of the most common mechanisms by which such structural degradation occurs.There has been increasing attention in recent years toward seismic resilience in communities and their constituent construction;however,to date,studies have neglected the effect of natural aging.This study aims to examine the effect of reinforcement corrosion on the seismic resilience of RC frames that are designed according to Chinese seismic design codes.A total of twenty RC frames are used to represent design and construction that is typical of coastal China,with consideration given to various seismic fortification levels and elevation arrangements.Seismic fragility relationships are developed for case frames under varying levels of reinforcement corrosion,i.e.,corrosion rates are increased from 5%to 15%.Subsequently,the seismic resilience levels of uncorroded and corroded RC frames are compared using a normalized loss factor.It was found that the loss of resilience of the corroded frames is greater than that of their uncorroded counterparts.At the Rare Earthquake hazard level,the corrosioninduced increase in loss of resilience can be more than 200%,showing the significant effect of reinforcement corrosion on structural resilience under the influence of earthquakes.展开更多
Following several damaging earthquakes in China, research has been devoted to find the causes of the collapse of reinforced concrete （RC） building sand studying the vulnerability of existing buildings. The Chinese C...Following several damaging earthquakes in China, research has been devoted to find the causes of the collapse of reinforced concrete （RC） building sand studying the vulnerability of existing buildings. The Chinese Code for Seismic Design of Buildings （CCSDB） has evolved over time, however, there is still reported earthquake induced damage of newly designed RC buildings. Thus, to investigate modern Chinese seismic design code, three low-, mid- and high-rise RC frames were designed according to the 2010 CCSDB and the corresponding vulnerability curves were derived by computing a probabilistic seismic demand model （PSDM）.The PSDM was computed by carrying out nonlinear time history analysis using thirty ground motions obtained from the Pacific Earthquake Engineering Research Center. Finally, the PSDM was used to generate fragility curves for immediate occupancy, significant damage, and collapse prevention damage levels. Results of the vulnerability assessment indicate that the seismic demands on the three different frames designed according to the 2010 CCSDB meet the seismic requirements and are almost in the same safety level.展开更多
A large number of buildings were seriously damaged or collapsed in the "5.12" Wenchuan earthquake. Based on field surveys and studies of damage to different types of buildings, seismic design codes have been...A large number of buildings were seriously damaged or collapsed in the "5.12" Wenchuan earthquake. Based on field surveys and studies of damage to different types of buildings, seismic design codes have been updated. This paper briefly summarizes some of the major revisions that have been incorporated into the "Standard for classification of seismic protection of building constructions GB50223-2008" and "Code for Seismic Design of Buildings GB50011-2001." The definition of seismic fortification class for buildings has been revisited, and as a result, the seismic classifications for schools, hospitals and other buildings that hold large populations such as evacuation shelters and information centers have been upgraded in the GB50223-2008 Code. The main aspects of the revised GB50011-2001 code include: (a) modification of the seismic intensity specified for the Provinces of Sichuan, Shanxi and Gansu; (b) basic conceptual design for retaining walls and building foundations in mountainous areas; (c) regularity of building configuration; (d) integration of masonry structures and precast RC floors; (e) requirements for calculating and detailing stair shafts; and (f) limiting the use of single-bay RC frame structures. Some significant examples of damage in the epicenter areas are provided as a reference in the discussion on the consequences of collapse, the importance of duplicate structural systems, and the integration of RC and masonry structures.展开更多
Many researchers have developed new calculation methods to analyze seismic slope stability problems, but the conventional pseudo-static method is still widely used in engineering design due to its simplicity. Based on...Many researchers have developed new calculation methods to analyze seismic slope stability problems, but the conventional pseudo-static method is still widely used in engineering design due to its simplicity. Based on the Technical Code for Building Slope Engineering（GB 50330-2013） of China and the Guidelines for Evaluating and Mitigating Seismic Hazards in California（SP117）, a comparative study on the pseudo-static method was performed. The results indicate that the largest difference between these two design codes lies in determination of the seismic equivalence reduction factor( f;). The GB 50330-2013 code specifies a single value for f;of 0.25. In SP117, numerous factors,such as magnitude and distance, are considered in determining f;. Two case studies show that the types of slope stability status evaluated by SP117 are in agreement with those evaluated by the seismic time-history stability analysis and Newmark displacement analysis. The factors of safety evaluated by SP117 can be used in practice for safe design. However, the factors of safety evaluated by GB 50330-2013 are risky for slope seismic design.展开更多
A novel Variable-Length Code (VLC), called Alternate VLC (AVLC), is proposed in this letter, which employs two types of VLC to encode source symbols alternately. Its advantage is that it can not only stop the symbol e...A novel Variable-Length Code (VLC), called Alternate VLC (AVLC), is proposed in this letter, which employs two types of VLC to encode source symbols alternately. Its advantage is that it can not only stop the symbol error propagation effect, but also correct symbol insertion errors and avoid symbol deletion er-rors, so the original sequence number of symbols can be kept correctly, which is very important in video com-munication.展开更多
Unreinforced Masonry (URM) is the most common partitioning material in framed buildings in India and many other countries. Although it is well-known that under lateral loading the behavior and modes of failure of the ...Unreinforced Masonry (URM) is the most common partitioning material in framed buildings in India and many other countries. Although it is well-known that under lateral loading the behavior and modes of failure of the frame buildings change significantly due to infill-frame interaction, the general design practice is to treat infills as nonstructural elements and their stiffness, strength and interaction with the frame is often ignored, primarily because of difficulties in simulation and lack of modeling guidelines in design codes. The Indian Standard, like many other national codes, does not provide explicit insight into the anticipated performance and associated vulnerability of infilled frames. This paper presents an analytical study on the seismic performance and fragility analysis of Indian code-designed RC frame buildings with and without URM infills. Infills are modeled as diagonal struts as per ASCE 41 guidelines and various modes of failure are considered. HAZUS methodology along with nonlinear static analysis is used to compare the seismic vulnerability of bare and infilled frames. The comparative study suggests that URM infills result in a significant increase in the seismic vulnerability of RC frames and their effect needs to be properly incorporated in design codes.展开更多
In recent years,with the continuous expansion of China's infrastructure construction,related construction work,including highway and bridge construction,has been steadily progressing.Among them,bridges are an impo...In recent years,with the continuous expansion of China's infrastructure construction,related construction work,including highway and bridge construction,has been steadily progressing.Among them,bridges are an important component of infrastructure construction,and their safety and stability are related to the travel of the masses and even the safety of their lives.China has a strict management system for bridge design specifications.This article mainly takes long-span highway bridges as an example to study the key issues of its design specifications and proposes countermeasures for related work.展开更多
Secret sharing has been a subject of study for over 30 years. The coding theory has been an important role in the constructing of the secret sharing schemes. It is known that every linear code can be used to construct...Secret sharing has been a subject of study for over 30 years. The coding theory has been an important role in the constructing of the secret sharing schemes. It is known that every linear code can be used to construct the secret sharing schemes. Since the code of a symmetric （V, k, λ）-design is a linear code, this study is about the secret sharing schemes based on C of Fp-code C of asymmetric （v, k, λ）-design.展开更多
For the dynamic demand assessment of bridge structures under ship impact loading,it may be prudent to adopt analytical models which permit rapid analysis with reasonable accuracy.Herein,a nonlinear dynamic macro-eleme...For the dynamic demand assessment of bridge structures under ship impact loading,it may be prudent to adopt analytical models which permit rapid analysis with reasonable accuracy.Herein,a nonlinear dynamic macro-element is proposed and implemented to quantify the demand of bridge substructures subjected to ship collisions.In the proposed nonlinear macro-element,a combination of an elastic-plastic spring and a dashpot in parallel is employed to describe the mechanical behavior of ship-bows with strain rate effects.Based on the analytical model using the proposed macro-element,a typical substructure under 5000 deadweight tonnage(DWT) ship collision is discussed.Our analyses indicate that the responses of the structure using the nonlinear macro-element agree with the results from the high resolution model,but the efficiency and feasibility of the proposed method increase significantly in practical applications.Furthermore,comparisons between some current design codes(AASHTO,JTGD60-2004,and TB10002.1-2005) and the developed dynamic analysis method suggest that these design codes may be improved,at least to consider the effect of dynamic amplification on structural demand.展开更多
Recent seismic events have raised concerns over the safety and vulnerability of reinforced concrete moment resisting frame ＂RC-MRF＂ buildings. The seismic response of such buildings is greatly dependent on the compu...Recent seismic events have raised concerns over the safety and vulnerability of reinforced concrete moment resisting frame ＂RC-MRF＂ buildings. The seismic response of such buildings is greatly dependent on the computational tools used and the inherent assumptions in the modelling process. Thus, it is essential to investigate the sensitivity of the response demands to the corresponding modelling assumption. Many parameters and assumptions are justified to generate effective structural finite element（FE） models of buildings to simulate lateral behaviour and evaluate seismic design demands. As such, the present study focuses on the development of reliable FE models with various levels of refinement. The effects of the FE modelling assumptions on the seismic response demands on the design of buildings are investigated. the predictive ability of a FE model is tied to the accuracy of numerical analysis; a numerical analysis is performed for a series of symmetric buildings in active seismic zones. The results of the seismic response demands are presented in a comparative format to confirm drift and strength limits requirements. A proposed model is formulated based on a simplified modeling approach, where the most refined model is used to calibrate the simplified model.展开更多
The evolution of leakage is studied using detailed contact finite element analysis. The distribution of stress at the gasket is analyzed using a contact condition based on slide-line elements using ABAQUS, a commercia...The evolution of leakage is studied using detailed contact finite element analysis. The distribution of stress at the gasket is analyzed using a contact condition based on slide-line elements using ABAQUS, a commercial finite element code, Slide-line elements also take into account pressure penetration as contact that is lost between flange and gasket. Results are presented for a particular flange, a raised face flange sealed by a mild steel gasket. A comparison of the results from the gasket contact analysis and the contact conditions specified by the ASME Boiler and Pressure Vessel Code, Sections VIII, Division 1 shows that the conditions specified in the ASME Code predict leakage relatively accurately.展开更多
In multipath environments, the error rate performance of orthogonal frequency division multiplexing （OFDM） is severely degraded by the deep fading subcarriers. Powerful error-correcting codes must be used with OFDM....In multipath environments, the error rate performance of orthogonal frequency division multiplexing （OFDM） is severely degraded by the deep fading subcarriers. Powerful error-correcting codes must be used with OFDM. This paper presents a quasi-cyclic low-density parity-check （LDPC） coded OFDM system, in which the redundant bits of each codeword are mapped to a higher-order modulation constellation. The op- timal degree distribution was calculated using density evolution. The corresponding quasi-cyclic LDPC code was then constructed using circulant permutation matrices. Group shuffled message passing scheduling was used in the iterative decoding. Simulation results show that the system achieves better error rate performance and faster decoding convergence than conventional approaches on both additive white Gaussian noise （AWGN） and Rayleigh fading channels.展开更多
Currently,the design practice of highway bridges around the world are moving towards limit states design,a reliability-based design procedure.Canadian Highway Bridge Design Code(CHBDC)is the first design code entirely...Currently,the design practice of highway bridges around the world are moving towards limit states design,a reliability-based design procedure.Canadian Highway Bridge Design Code(CHBDC)is the first design code entirely developed based on limit states design philosophy,including foundations and FRP components.However,reliability of a structure decreases in service due to environmental attacks and material deterioration such as fatigue,corrosion and many other reasons.Therefore,the structure should be inspected periodically,and the reliability of the structure should be evaluated according to its age and field data.If its reliability is reduced to a certain level,a repair should be scheduled as well as some preventive maintenance measures should be implemented to prevent further deterioration.Recently,many research works have been conducted to investigate reliability-deterioration mechanisms for each type of infrastructure and its components,optimize the inspection and maintenance strategy,predict remaining service life,estimate its life cycle cost.This paper is focused on the study of reliability-deterioration mechanisms of slab on steel girder bridges due to fatigue and corrosion of steel girders as well as corrosion of reinforcement in the deck slab.Examples will also be given to illustrate the proposed life cycle management strategy for composite slab on steel girder bridges.展开更多
Starting from the definition of Basic Complementary Coding (CC) Pairs, this paper presents a scheme of designing CC signals for practical applications. In comparison with the scheme based directly on the definition of...Starting from the definition of Basic Complementary Coding (CC) Pairs, this paper presents a scheme of designing CC signals for practical applications. In comparison with the scheme based directly on the definition of CC pairs, the present scheme can speed up the operation process for finding CC pairs by 24 × 2N/2 times when the number of coding units N>4.展开更多
In this paper using the weight enumerators of a linear [n, k]--code, we give a theorem about minimal codewords. In this n context, we show that while 1 E C if Wmin〉 n/2 in the binary [n, k] --code C, then all of the...In this paper using the weight enumerators of a linear [n, k]--code, we give a theorem about minimal codewords. In this n context, we show that while 1 E C if Wmin〉 n/2 in the binary [n, k] --code C, then all of the nonzero codewords of C are 2 minimal. Therefore, we obtain a corollary.展开更多
A uniaxial tension test is commonly used to determine the mechanical properties of steel,but it has no meaning for the response of the material in a structure.The test was developed as a consensus solution by producer...A uniaxial tension test is commonly used to determine the mechanical properties of steel,but it has no meaning for the response of the material in a structure.The test was developed as a consensus solution by producers,fabricators,designers and code writers,to have a standard by which similar materials could be compared to a common base.It does not represent the actual behavior of the steel in a structure,and was never intended to do so.To study the true behavior of the structure and how the material responds it would be better to determine the strains and deformations that will take place during actual service condition.Such characteristics reflect the real behavior,whether in the elastic or inelastic range.If stresses or forces are needed,these are easily determined by the value of the strain and the relevant material modulus,along with the type of cross section,whether elastic or inelastic.The paper addresses the properties of a range of structural steels,how these are incorporated into design standards and how the standards define deformation characteristics and demands for bolted and welded connections.展开更多
Because of the deltaic nature of the Netherlands,deep soft soil deposits are widespread.Due to the population density exploitation of underground space is vital for commercial developments and transport networks.Piles...Because of the deltaic nature of the Netherlands,deep soft soil deposits are widespread.Due to the population density exploitation of underground space is vital for commercial developments and transport networks.Piles are used as primary support elements in deep excavations,cut and cover tunnels,quay walls,flood defences and to provide uplift resistance to the base of tunnels and basements.This paper examines empirical correlations linking the Cone Penetration Test(CPT)end resistance qc and the resistance of deep foundations in sand.It is found that correlations between qc and pile end resistance are independent of pile diameter.However,the impact of installation method,residual load,plugging and sand creep should be considered.In the case of shaft resistance,constant correlation factors between qc and average shaft resistance are possible for non-displacement piles.For the case of displacement piles,correlations that include the effects of friction fatigue and pile plugging during installation are recommended.展开更多
基金funded by the Ghent University Special Research Fund under grant 01N01219“Multi-objective societal optimization of structural fire safety investments for uncommon projects using advanced regression techniques”.
文摘Adequacy of structural fire design in uncommon structures is conceptually ensured through cost-benefit analysis where the future costs are balanced against the benefits of safety investment.Cost-benefit analyses,however,are complicated and computationally challenging,and hence impractical for application to individual projects.To address this issue,design guidance proposes target reliability indices for normal design conditions,but no target reliability indices are defined for structural fire design.We revisit the background of the cost-optimization based approach underlying normal design target reliability indices then we extend this approach for the case of fire design of structures.We also propose a modified objective function for cost-optimization which simplifies the evaluation of target reliability indices and reduces the number of assumptions.The optimum safety level is expressed as a function of a new dimensionless variable named“Damage-to-investment indicator”(DII).The cost optimization approach is validated for the target reliability indices for normal design condition.The method is then applied for evaluating DII and the associated optimum reliability indices for fire-exposed structures.Two case studies are presented:(i)a one-way loaded reinforced concrete slab and(ii)a steel column under axial loading.This study thus provides a framework for deriving optimum(target)reliability index for structural fire design which can support the development of rational provisions in codes and standards.
基金National Natural Science Foundation of China for Distinguished Young Scholars under Grant No.52125806Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant No.2021B03。
文摘On March 28,2025,an M_(w) 7.7 earthquake struck near Mandalay,Myanmar,producing intense ground shaking.Strong motion recorded at a station close to the fault indicated a peak ground acceleration of 1.066 g in the vertical direction and 0.631 g in the horizontal direction.The earthquake caused collapse or severe damage of numerous buildings,resulting in thousands of fatalities and injuries,as well as substantial economic losses.The authors participated in the post-earthquake emergency response as members of the China Search and Rescue Team.During the rescue operations,an investigation into the characteristics of collapsed structures was conducted and the stability of building debris was assessed to ensure the safety of rescue efforts.Subsequently,a rapid seismic safety assessment of affected structures was carried out,including nine city residential blocks,two hospitals,and two apartments.Preliminary analyses indicate that the main causes of structural failure were insufficient cross-sectional dimensions of beams and columns,inadequate stirrup reinforcement,and lack of structural redundancy.
基金National Natural Science Foundation of China under Grant No.51778198the Natural Science Foundation for Excellent Young Scientists of Heilongjiang Province under Grant No.YQ2020E023。
文摘The natural landscape in China exposes many existing RC buildings to aggressive environments.Such exposure can lead to deterioration in structural performance with regard to resisting events such as earthquakes.Corrosion of embedded reinforcement is one of the most common mechanisms by which such structural degradation occurs.There has been increasing attention in recent years toward seismic resilience in communities and their constituent construction;however,to date,studies have neglected the effect of natural aging.This study aims to examine the effect of reinforcement corrosion on the seismic resilience of RC frames that are designed according to Chinese seismic design codes.A total of twenty RC frames are used to represent design and construction that is typical of coastal China,with consideration given to various seismic fortification levels and elevation arrangements.Seismic fragility relationships are developed for case frames under varying levels of reinforcement corrosion,i.e.,corrosion rates are increased from 5%to 15%.Subsequently,the seismic resilience levels of uncorroded and corroded RC frames are compared using a normalized loss factor.It was found that the loss of resilience of the corroded frames is greater than that of their uncorroded counterparts.At the Rare Earthquake hazard level,the corrosioninduced increase in loss of resilience can be more than 200%,showing the significant effect of reinforcement corrosion on structural resilience under the influence of earthquakes.
基金National Natural Science Foundation of China Under Grant No.51108105,90815029,50938006 Research Fund for the Doctoral Program of Higher Education of China Under Grant No.20094410120002+3 种基金 Major Program of National Natural Science Foundation of China Under Grant No.90815027Key Projects in the National Science&Technology Pillar Program during the Eleventh Five-Year Plan Period Under Grant No.2009BAJ28B03Fund for High School in Guangzhou (10A057)the Open Foundation of State Key Laboratory of Subtropical Building Science(2011KB15)
文摘Following several damaging earthquakes in China, research has been devoted to find the causes of the collapse of reinforced concrete （RC） building sand studying the vulnerability of existing buildings. The Chinese Code for Seismic Design of Buildings （CCSDB） has evolved over time, however, there is still reported earthquake induced damage of newly designed RC buildings. Thus, to investigate modern Chinese seismic design code, three low-, mid- and high-rise RC frames were designed according to the 2010 CCSDB and the corresponding vulnerability curves were derived by computing a probabilistic seismic demand model （PSDM）.The PSDM was computed by carrying out nonlinear time history analysis using thirty ground motions obtained from the Pacific Earthquake Engineering Research Center. Finally, the PSDM was used to generate fragility curves for immediate occupancy, significant damage, and collapse prevention damage levels. Results of the vulnerability assessment indicate that the seismic demands on the three different frames designed according to the 2010 CCSDB meet the seismic requirements and are almost in the same safety level.
基金National Natural Science Foundation of China Under Grant No.50439010 NSFC and Korea Science and Engineering Foundation Under Grant No.50811140341
文摘A large number of buildings were seriously damaged or collapsed in the "5.12" Wenchuan earthquake. Based on field surveys and studies of damage to different types of buildings, seismic design codes have been updated. This paper briefly summarizes some of the major revisions that have been incorporated into the "Standard for classification of seismic protection of building constructions GB50223-2008" and "Code for Seismic Design of Buildings GB50011-2001." The definition of seismic fortification class for buildings has been revisited, and as a result, the seismic classifications for schools, hospitals and other buildings that hold large populations such as evacuation shelters and information centers have been upgraded in the GB50223-2008 Code. The main aspects of the revised GB50011-2001 code include: (a) modification of the seismic intensity specified for the Provinces of Sichuan, Shanxi and Gansu; (b) basic conceptual design for retaining walls and building foundations in mountainous areas; (c) regularity of building configuration; (d) integration of masonry structures and precast RC floors; (e) requirements for calculating and detailing stair shafts; and (f) limiting the use of single-bay RC frame structures. Some significant examples of damage in the epicenter areas are provided as a reference in the discussion on the consequences of collapse, the importance of duplicate structural systems, and the integration of RC and masonry structures.
基金supported by the National Key R&D Program of China(Grant No.2017YFC0404804)the National Natural Science Foundation of China(Grant No.51509019)
文摘Many researchers have developed new calculation methods to analyze seismic slope stability problems, but the conventional pseudo-static method is still widely used in engineering design due to its simplicity. Based on the Technical Code for Building Slope Engineering（GB 50330-2013） of China and the Guidelines for Evaluating and Mitigating Seismic Hazards in California（SP117）, a comparative study on the pseudo-static method was performed. The results indicate that the largest difference between these two design codes lies in determination of the seismic equivalence reduction factor( f;). The GB 50330-2013 code specifies a single value for f;of 0.25. In SP117, numerous factors,such as magnitude and distance, are considered in determining f;. Two case studies show that the types of slope stability status evaluated by SP117 are in agreement with those evaluated by the seismic time-history stability analysis and Newmark displacement analysis. The factors of safety evaluated by SP117 can be used in practice for safe design. However, the factors of safety evaluated by GB 50330-2013 are risky for slope seismic design.
文摘A novel Variable-Length Code (VLC), called Alternate VLC (AVLC), is proposed in this letter, which employs two types of VLC to encode source symbols alternately. Its advantage is that it can not only stop the symbol error propagation effect, but also correct symbol insertion errors and avoid symbol deletion er-rors, so the original sequence number of symbols can be kept correctly, which is very important in video com-munication.
文摘Unreinforced Masonry (URM) is the most common partitioning material in framed buildings in India and many other countries. Although it is well-known that under lateral loading the behavior and modes of failure of the frame buildings change significantly due to infill-frame interaction, the general design practice is to treat infills as nonstructural elements and their stiffness, strength and interaction with the frame is often ignored, primarily because of difficulties in simulation and lack of modeling guidelines in design codes. The Indian Standard, like many other national codes, does not provide explicit insight into the anticipated performance and associated vulnerability of infilled frames. This paper presents an analytical study on the seismic performance and fragility analysis of Indian code-designed RC frame buildings with and without URM infills. Infills are modeled as diagonal struts as per ASCE 41 guidelines and various modes of failure are considered. HAZUS methodology along with nonlinear static analysis is used to compare the seismic vulnerability of bare and infilled frames. The comparative study suggests that URM infills result in a significant increase in the seismic vulnerability of RC frames and their effect needs to be properly incorporated in design codes.
文摘In recent years,with the continuous expansion of China's infrastructure construction,related construction work,including highway and bridge construction,has been steadily progressing.Among them,bridges are an important component of infrastructure construction,and their safety and stability are related to the travel of the masses and even the safety of their lives.China has a strict management system for bridge design specifications.This article mainly takes long-span highway bridges as an example to study the key issues of its design specifications and proposes countermeasures for related work.
文摘Secret sharing has been a subject of study for over 30 years. The coding theory has been an important role in the constructing of the secret sharing schemes. It is known that every linear code can be used to construct the secret sharing schemes. Since the code of a symmetric （V, k, λ）-design is a linear code, this study is about the secret sharing schemes based on C of Fp-code C of asymmetric （v, k, λ）-design.
基金supported by the Ministry of Science and Technology of China (No. SLDRCE 09-B-08)the National Natural Science Foundation of China (Nos. 50978194 and 90915011)+1 种基金the Kwang-Hua Fund for College of Civil Engineering,Tongji Universitythe Fund of National Engineering and Research Center for Highways in Mountain Area (No. gsgzj-2010-01),China
文摘For the dynamic demand assessment of bridge structures under ship impact loading,it may be prudent to adopt analytical models which permit rapid analysis with reasonable accuracy.Herein,a nonlinear dynamic macro-element is proposed and implemented to quantify the demand of bridge substructures subjected to ship collisions.In the proposed nonlinear macro-element,a combination of an elastic-plastic spring and a dashpot in parallel is employed to describe the mechanical behavior of ship-bows with strain rate effects.Based on the analytical model using the proposed macro-element,a typical substructure under 5000 deadweight tonnage(DWT) ship collision is discussed.Our analyses indicate that the responses of the structure using the nonlinear macro-element agree with the results from the high resolution model,but the efficiency and feasibility of the proposed method increase significantly in practical applications.Furthermore,comparisons between some current design codes(AASHTO,JTGD60-2004,and TB10002.1-2005) and the developed dynamic analysis method suggest that these design codes may be improved,at least to consider the effect of dynamic amplification on structural demand.
基金Scientific Research Deanship,Taibah University Grant No.6363/436
文摘Recent seismic events have raised concerns over the safety and vulnerability of reinforced concrete moment resisting frame ＂RC-MRF＂ buildings. The seismic response of such buildings is greatly dependent on the computational tools used and the inherent assumptions in the modelling process. Thus, it is essential to investigate the sensitivity of the response demands to the corresponding modelling assumption. Many parameters and assumptions are justified to generate effective structural finite element（FE） models of buildings to simulate lateral behaviour and evaluate seismic design demands. As such, the present study focuses on the development of reliable FE models with various levels of refinement. The effects of the FE modelling assumptions on the seismic response demands on the design of buildings are investigated. the predictive ability of a FE model is tied to the accuracy of numerical analysis; a numerical analysis is performed for a series of symmetric buildings in active seismic zones. The results of the seismic response demands are presented in a comparative format to confirm drift and strength limits requirements. A proposed model is formulated based on a simplified modeling approach, where the most refined model is used to calibrate the simplified model.
文摘The evolution of leakage is studied using detailed contact finite element analysis. The distribution of stress at the gasket is analyzed using a contact condition based on slide-line elements using ABAQUS, a commercial finite element code, Slide-line elements also take into account pressure penetration as contact that is lost between flange and gasket. Results are presented for a particular flange, a raised face flange sealed by a mild steel gasket. A comparison of the results from the gasket contact analysis and the contact conditions specified by the ASME Boiler and Pressure Vessel Code, Sections VIII, Division 1 shows that the conditions specified in the ASME Code predict leakage relatively accurately.
文摘In multipath environments, the error rate performance of orthogonal frequency division multiplexing （OFDM） is severely degraded by the deep fading subcarriers. Powerful error-correcting codes must be used with OFDM. This paper presents a quasi-cyclic low-density parity-check （LDPC） coded OFDM system, in which the redundant bits of each codeword are mapped to a higher-order modulation constellation. The op- timal degree distribution was calculated using density evolution. The corresponding quasi-cyclic LDPC code was then constructed using circulant permutation matrices. Group shuffled message passing scheduling was used in the iterative decoding. Simulation results show that the system achieves better error rate performance and faster decoding convergence than conventional approaches on both additive white Gaussian noise （AWGN） and Rayleigh fading channels.
文摘Currently,the design practice of highway bridges around the world are moving towards limit states design,a reliability-based design procedure.Canadian Highway Bridge Design Code(CHBDC)is the first design code entirely developed based on limit states design philosophy,including foundations and FRP components.However,reliability of a structure decreases in service due to environmental attacks and material deterioration such as fatigue,corrosion and many other reasons.Therefore,the structure should be inspected periodically,and the reliability of the structure should be evaluated according to its age and field data.If its reliability is reduced to a certain level,a repair should be scheduled as well as some preventive maintenance measures should be implemented to prevent further deterioration.Recently,many research works have been conducted to investigate reliability-deterioration mechanisms for each type of infrastructure and its components,optimize the inspection and maintenance strategy,predict remaining service life,estimate its life cycle cost.This paper is focused on the study of reliability-deterioration mechanisms of slab on steel girder bridges due to fatigue and corrosion of steel girders as well as corrosion of reinforcement in the deck slab.Examples will also be given to illustrate the proposed life cycle management strategy for composite slab on steel girder bridges.
基金The project supported by The National Natural Science Foundation of China
文摘Starting from the definition of Basic Complementary Coding (CC) Pairs, this paper presents a scheme of designing CC signals for practical applications. In comparison with the scheme based directly on the definition of CC pairs, the present scheme can speed up the operation process for finding CC pairs by 24 × 2N/2 times when the number of coding units N>4.
文摘In this paper using the weight enumerators of a linear [n, k]--code, we give a theorem about minimal codewords. In this n context, we show that while 1 E C if Wmin〉 n/2 in the binary [n, k] --code C, then all of the nonzero codewords of C are 2 minimal. Therefore, we obtain a corollary.
文摘A uniaxial tension test is commonly used to determine the mechanical properties of steel,but it has no meaning for the response of the material in a structure.The test was developed as a consensus solution by producers,fabricators,designers and code writers,to have a standard by which similar materials could be compared to a common base.It does not represent the actual behavior of the steel in a structure,and was never intended to do so.To study the true behavior of the structure and how the material responds it would be better to determine the strains and deformations that will take place during actual service condition.Such characteristics reflect the real behavior,whether in the elastic or inelastic range.If stresses or forces are needed,these are easily determined by the value of the strain and the relevant material modulus,along with the type of cross section,whether elastic or inelastic.The paper addresses the properties of a range of structural steels,how these are incorporated into design standards and how the standards define deformation characteristics and demands for bolted and welded connections.
基金Some of the work presented in this paper was completed together with a number of former research students and collaborators who include:Prof.Barry Lahane,Dr.Lisa Kirwan,Dr.Ali Tolooiyan,David Cadogan,Dr.Cormac Reale and others.The permission of the Port of Rotterdam and Funderingstechnieken Verstraeten bv.and BNED bv.to publish pile load test data is gratefully acknowledged.
文摘Because of the deltaic nature of the Netherlands,deep soft soil deposits are widespread.Due to the population density exploitation of underground space is vital for commercial developments and transport networks.Piles are used as primary support elements in deep excavations,cut and cover tunnels,quay walls,flood defences and to provide uplift resistance to the base of tunnels and basements.This paper examines empirical correlations linking the Cone Penetration Test(CPT)end resistance qc and the resistance of deep foundations in sand.It is found that correlations between qc and pile end resistance are independent of pile diameter.However,the impact of installation method,residual load,plugging and sand creep should be considered.In the case of shaft resistance,constant correlation factors between qc and average shaft resistance are possible for non-displacement piles.For the case of displacement piles,correlations that include the effects of friction fatigue and pile plugging during installation are recommended.
