Effect of URM infills on seismic vulnerability of Indian code designed RC frame buildings

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.

Code Design and Shuffled Iterative Decoding of a Quasi-Cyclic LDPC Coded OFDM System

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.

Seismic fragility assessment of RC frame structure designed according to modern Chinese code for seismic design of buildings

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.

Revision of seismic design codes corresponding to building damagesin the “5.12” Wenchuan earthquake

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.

A comparative study of pseudo-static slope stability analysis using different design codes

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.

Seismic resilience assessment of corroded reinforced concrete structures designed to the Chinese codes

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.

Half Rate Quasi Cyclic Low Density Parity Check Codes Based on Combinatorial Designs

This paper presents new half rate Quasi Cyclic Low Density Parity Check (QC- LDPC) codes formed on the basis of combinatorial designs. In these codes, circulant matrices of the parity check matrix are formed on the basis of subsets in which the difference between any two elements of a subset is unique with all differences obtained from the same or different subsets. This structure of circulant matrices guarantees non-existence of cycle-4 in the Tanner graph of QC-LDPC codes. First, an irregular code with girth 6 constituted by two rows of circulant matrices is proposed. Then, more criteria will be considered on the structure of subsets with the mentioned feature aiming to represent a new scheme of regular QC-LPDC codes with girth at least 8. From simulations, it is confirmed that codes have similar to or better performance than other well-known half rate codes, while require lower complexity in their design.

REVERSE DESIGN APPROACH FOR MECHANISM TRAJECTORY BASED ON CODE-CHAINS MATCHING

Aiming at the problem of reverse-design of mechanism, a method based on the matching of trajectory code-chains is presented. The motion trajectory of mechanism is described with code-chain, which is normalized to simplify the operation of geometric transformation. The geometric transforma-tion formulas of scale, mirror and rotation for trajectory code-chain are defined, and the reverse de-sign for mechanism trajectory is realized through the analysis and solution of similarity matching between the desired trajectory and the predefined trajectory. The algorithm program and prototype system of reverse design for mechanism trajectory are developed. Application samples show that the method can break the restriction of trajectory patterns in matching, meet the demand of partial match-ing, and overcome the influence of geometric transformation of trajectory on the reverse design for mechanism.

Comparison of seismic actions and structural design requirements in Chinese Code GB 50011 and International Standard ISO 3010

This papcr presents a comparison between the Chinese Code GB50011-2001 and the International Standard ISO3010:2001(E),emphasizing the similarities and differences related to design requirements,seismic actions and analytical approaches.Similarities include:earthquake return period,conceptual design,site classification,structural strength and ductility requirements,deformation limits,response spectra,seismic analysis procedures,isolation and energy dissipation, and nonstructural elements.Differences exist in the following areas:seismic levels,earthquake loading,mode damping factors and structural control.

Seismic performance evaluation of typical dampers designed by Chinese building code

Adding dampers is a commonly adopted seismic risk mitigation strategy for modern buildings, and the corresponding design procedure of dampers has been well established by the Chinese Building Code. Even though all types of dampers are designed by the same procedure, actual seismic performance of the building may differ from one to the others. In this study, a nine-story benchmark steel building is established, and three different and typical types of dampers are designed according to the Chinese Building Code to realize structural vibration control under strong earthquake excitation. The seismic response of the prototype building equipped with a viscoelastic damper, viscous damper and buckling-restrained brace(BRB) subjected to 10 earthquake records are calculated, and Incremental Dynamic Analysis(IDA) is performed to describe progressive damage of the structure under increasing earthquake intensity. In the perspective of fragility, it shows that the viscoelastic damper has the highest collapse margin ratio(CMR), and the viscous damper provides the best drift control. Both the BRB and viscoelastic dampers can effectively reduce the floor acceleration responses in the mid-rise building.

Code Component Reuse Supporting Environment (CCRSE) and Its Design Strategy

Code Component Reuse Supporting Environment (CCRSE), which has been developed by us, is an integrated development environment. CCRSE can provide comprehensive supports for the whole process of reusing code component in the manner of dynamic composition. The architecture and functionality of CCRSE are introduced. The key achievement is giving the three strategies that are vital to successfully design CCRSE. The three strategies include: (1) according to the three pivotal technologies (encapsulation, composition and management) for supporting composition reuse of code component, design three tools respectively. (2) keep tool for supporting code component development independent of tool for supporting code component composition. (3) strictly restrict code component specification, provide the strong plug and play support for code component composition reuse, and furthest provide transparence to strictly restricted specification of code component in development of component itself.

Analysis of Key Issues in Design Codes for Long-Span Highway Bridges

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.

Secret Sharing Schemes Based on the Dual Code of the Code of a Symmetric （v, k, λ）-Design and Minimal Access Sets

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.

A Codebook Design Method for Robust VQ-Based Face Recognition Algorithm

In this paper, we present a theoretical codebook design method for VQ-based fast face recognition algorithm to im-prove recognition accuracy. Based on the systematic analysis and classification of code patterns, firstly we theoretically create a systematically organized codebook. Combined with another codebook created by Kohonen’s Self-Organizing Maps (SOM) method, an optimized codebook consisted of 2×2 codevectors for facial images is generated. Experimental results show face recognition using such a codebook is more efficient than the codebook consisted of 4×4 codevector used in conventional algorithm. The highest average recognition rate of 98.6% is obtained for 40 persons’ 400 images of publicly available face database of AT&T Laboratories Cambridge containing variations in lighting, posing, and expressions. A table look-up (TLU) method is also proposed for the speed up of the recognition processing. By applying this method in the quantization step, the total recognition processing time achieves only 28 msec, enabling real-time face recognition.

“私教”还是“枪手”:基于大模型的计算机实践教学探索

以大模型为代表的新一代人工智能技术正深刻影响传统教学模式。在计算机实践教学过程中,如果大模型被合理应用,它可以充当学生的“私教”,辅助学生的个性化学习;否则大模型可能沦为学生完成作业的“枪手”,削弱学生的独立思考及实践能力。该文首先论述了计算机实践教学的层次,并分析了大模型对各个层次实践教学的正面和负面影响。然后,以“算法设计与分析”课程为案例,设计了面向算法设计实践的大模型应用模式,包括过程报告、逆向思考和集中考核等主要形式,初步应用结果表明,84.8%的学生在课程中使用大模型,其中51%的学生认可大模型的帮助作用,大模型应用显著提高了课程实践作业的完成度。

On Cross-Layer Design of AMC Based on Rate Compatible Punctured Turbo Codes

This paper extends the work on cross-layer design which combines adaptive modulation and coding at the physical layer and hybrid automatic repeat request protocol at the data link layer. By contrast with previous works on this topic, the present development and the performance analysis as well, is based on rate compatible punctured turbo codes. Rate compatibility provides incremental redundancy in transmission of parity bits for error correction at the data link layer. Turbo coding and iterative decoding gives lower packet error rate values in low signal-to-noise ratio regions of the adaptive modulation and coding (AMC) schemes. Thus, the applied cross-layer design results in AMC schemes can achieve better spectral efficiency than convolutional one while it retains the QoS requirements at the application layer. Numerical results in terms of spectral efficiency for both turbo and convolutional rate compatible punctured codes are presented. For a more comprehensive presentation, the performance of rate compatible LDPC is contrasted with turbo case as well as the performance complexity is discussed for each of the above codes.

教育法典基本原则的确立与展开

教育法典基本原则是贯穿教育法典编纂及实施的核心价值与根本规律,具有立法统领和适法指导的功能,是教育法典总则必不可少的组成部分。基于规范梳理和学理分析,教育法典的基本原则可提炼为依法治教原则、立德树人原则、教育公益性原则、教育自主性原则、教育公平与教育效益相结合原则、终身教育原则、教育领域多重利益兼顾原则和教育领域协同治理原则八个方面。这八项原则层层递进、彼此联动。基本原则的条款设计,应当把握独特性和体系性的平衡,精准呈现各项原则的基本内涵及原则之间的协同关系。

“无线通信原理”实践课程设计

针对现有教学以课堂授课为主要形式的状况,该文对“无线通信原理”的实践课程设计进行了讨论。该课程以二维图像为输入输出的通信系统作为实验对象,该系统涵盖信源编码、信道编码、调制解调和信道等模块。通过学生自主设计,深化对信息传输基本流程和不同信道影响的理解,同时提高实践能力。相对于传统实践课程,该实践课程更注重整个通信系统的设计,并引入5G时代先进的低密度奇偶校验码技术,加深学生对通信系统的理解,并对传输性能有直观的体验,为无线通信实践型人才培养提供新思路。

基于公路与城市桥梁抗震设计规范反应谱的全非平稳地震动过程模拟

【目的】生成拟合公路与城市桥梁抗震设计规范反应谱的全非平稳地震动过程代表性时程集合。【方法】首先,结合非平稳地震动过程的强度-频率调制函数和平稳地震动过程的Clough-Penzien功率谱模型,建立全非平稳地震动过程的演变功率谱模型;其次,依据相关规范确定演变功率谱模型参数取值;然后,根据全非平稳地震动过程模拟的谱表示方法,编写MATLAB程序,生成全非平稳地震动过程代表性时程集合,计算其均值反应谱和规范反应谱拟合误差,并进行迭代修正。【结果】依据公路与城市桥梁抗震设计规范给出了不同场地类别和设计地震分组的演变功率谱模型参数取值;生成的代表性时程集合具有全非平稳地震动的典型特征,其均值反应谱和规范反应谱整体拟合程度较好,平均相对误差均在5%以内。【结论】基于演变功率谱模型,通过编写全非平稳地震动过程模拟谱表示方法的MATLAB程序,可生成满足公路与城市桥梁抗震设计规范要求的全非平稳地震动过程代表性时程集合,其均值反应谱与规范反应谱拟合一致,验证了所给方法和MATLAB程序的有效性,可为桥梁结构抗震性能评估提供可靠的地震动输入。