• Low complexity MED algorithm based on numerical analysis theories

  YANG Xi, TIAN Chong, FANG Ruyi, LIU Zeyu, ZHANG Yinhang, LEI Kejun

  Available online:May 19, 2022  DOI: 10.16339/j.cnki.hdxbzkb.2022353

  Abstract(4185) HTML(0) PDF(1.21 M)( 17211)

  Abstract:The classical maximum eigenvalue detection (MED) algorithm has excellent performance in detecting correlated signals. However, with the increasing signal dimensionality, the MED algorithm faces serious problems in the calculation efficiency and implementation of test statistic and decision threshold, thus greatly limiting the further application of the algorithm in modern cognitive communication systems. To this end, a low-implementation complexity MED algorithm based on a numerical analysis theoretical framework is proposed. The new algorithm uses the Rayleigh quotient accelerated power method to iteratively compute the test statistic, which has a fast convergence rate in detecting high-dimensional signals compared with the classical power method; meanwhile, different from the classical look-up table method, a threshold calculation method based on the cubic spline interpolation method is proposed, which can quickly determine the decision threshold corresponding to any given target false-alarm probability. The proposed MED algorithm effectively improves the computational efficiency and reduces the complexity of algorithm implementation while maintaining the detection performance of the original algorithm, which is particularly attractive for spectrum sensing problems in high-dimensional conditions. Finally, the simulation results demonstrate the effectiveness of the proposed algorithm.

• Design of Terahertz Fundamental Up-conversion Mixer with Good Port-to-Port Isolation

  Meng Fanyi, Liu Hao

  Available online:May 19, 2022  DOI: 10.16339/j.cnki.hdxbzkb.2022355

  Abstract(1336) HTML(0) PDF(3.07 M)( 15114)

  Abstract:A terahertz fundamental up-conversion mixer with a high local oscillator (LO)/ radio frequency (RF) and local oscillator / intermediate frequency (IF) port isolation was presented, which was in the IHP 0.13μm SiGe BiCMOS process. The mixer adopted Gilbert’s double-balanced structure, local oscillator signal was transmitted through the Coplanar Waveguide (CPW) to suppress the transmission asymmetry caused by the strong parasitic coupling effect in the transmission process, which reduced the characteristic of LO/RF port isolation deterioration caused by the asymmetry. By adopting an asymmetric switch interconnection structure, the imbalance of the parasitic coupling of the local oscillator signal at the collectors of the switching transistors was reduced, and the cancellation efficiency of the local oscillator signal at the collectors of the switching transistors was improved. And the local oscillator signal was suppressed at the port of intermediate frequency by arranging the position of the transconductance transistors in a reasonable layout. The post-simulation results show that under the power supply voltage of 2.2V, the local oscillator signal is 230GHz and the intermediate frequency signal is 2-12GHz, when the up-conversion mixer works at 218-228GHz, the LO/RF port isolation is greater than 24dB, LO/IF port isolation is greater than 20dB, the conversion gain is -4dB to-3.4dB. The output 1dB compression point is -14.8dBm with an intermediate frequency signal is 10GHz. The DC power consumption is 42.4mW, the core area of the chip is 0.079mm2.

• Performance Analysis of RIS-assisted Hybrid RF-FSO Transmission Systems

  YUAN Yongjie, YANG Liang, CHEN Shenghai, MA Rongchang

  Available online:May 17, 2022  DOI: 10.16339/j.cnki.hdxbzkb.2022296

  Abstract(1105) HTML(0) PDF(965.81 K)( 15147)

  Abstract:Free space optical (FSO) communications offer high speed, low cost, and strong anti-interference ability. However, the atmospheric turbulence-induced fading causes deterioration in the performance of FSO communication systems. The conventional solution is to use RF links as parallel communication links to improve the system performance. On the other hand, reconfigurable intelligent surfaces (RIS) can be employed to further improve the received signal-to-noise ratio of the RF link due to its advantages of low loss, easy deployment, and no complex coding and decoding. In this paper, an RIS-assisted hybrid RF-FSO transmission system is proposed to improve the communication quality of service. Based on this hybrid model, exact expressions for the outage probability, average BER, and channel capacity are derived, and Monte-Carlo simulations are presented to verify the accuracy of the analytical results. Results show that the performance of the proposed system is significantly improved compared to the conventional hybrid RF-FSO system.

• Research on scattering characteristic of PT?symmetric beam based on piezoelectric shunting technology

  Wang Gang, Luo Caiming

  Available online:May 17, 2022  DOI:

  Abstract(941) HTML(0) PDF(1.51 M)( 14850)

  Abstract:The mechanism for asymmetric transmission is an important issue for enhanced sensing, amplification and asymmetric control of elastic waves. Parity-Time symmetric systems may provide a simple solution. The concept of Parity-Time symmetric systems comes from quantum mechanics, and one of its characteristics is unidirectional reflectionlessness. A PT symmetric beam for flexural waves is designed, which is based on piezoelectric shunting technology. Firstly, the PT symmetric condition is derived. Then, based on the effective medium method and finite element simulation, it is verified that the effective parameters of gain and loss unit meet the PT symmetric condition. The tunability of exception points is studied by changing the resonant frequency and the shunting resistance. Finally, the scattering property of the PT sym-metric beam is derived by transfer matrix method and finite element simulation, and the relationship between exceptional points and unidirectional non-reflection is illustrated. The calculated and simulated results show that the PT symmetric beam has several exceptional points including 511Hz and 520.5Hz. When the incident flexural waves of 511Hz is applied at the right side of the PT symmetric beam, the reflection coefficient is close to zero. However, when the frequency of the incident flexural waves changes to 520.5Hz, it should be applied on the left side of the PT symmetric beam in order to gain a total transmission without reflecting. The structure of the proposed PT symmetric beam is simple and the exceptional points of it are tunable, which can be used to achieve better asymmetric transmission of flexural wave.

• Research on Online Community Knowledge Sharing Scheme Based on Blockchain

  XIE Renqiang

  Available online:May 17, 2022  DOI: 10.16339/j.cnki.hdxbzkb.2022297

  Abstract(996) HTML(0) PDF(842.54 K)( 14686)

  Abstract:With the rapid development of Internet, virtual communities are emerging. While providing innovative resources, these communities also have problems such as low willingness of users to share and lack of good incentive mechanism. Blockchain can better solve these problems and promote community knowledge sharing. This paper constructs an online community knowledge sharing scheme based on Multi Chain, puts forward the resource access and storage mode of "metadata cloud storage" and designs the metadata information table in detail, designs the overall framework of the knowledge sharing scheme and the key processes of some businesses, puts forward the consensus mechanism of "Nominated Proof of Stake (NPOS) to design the blockchain network, Some functions of online community knowledge sharing are realized. Through analysis and experiment, the scheme of this paper has good scientific rationality, safety and execution efficiency, and has good reference value for the development of other related projects.

• T-shaped image dehazing network based on wavelet transform and attention mechanism

  YangYan, WuXuDong, DuKang

  Available online:May 17, 2022  DOI: 10.16339/j.cnki.hdxbzkb.2022299

  Abstract(1065) HTML(0) PDF(1.42 M)( 14900)

  Abstract:Affected by suspended particles such as haze in the atmosphere,images taken outdoors often suffer from low contrast and low visibility. Existing dehazing methods fail to make full use of the local feature information of the image, and cannot fully extract the global details of the image. Therefore, there are problems such as incomplete dehazing and loss of image details. For this reason, this paper proposes a T-shaped image dehazing network based on wavelet transform and attention mechanism. Specifically, the proposed network obtains the edge detail features of the hazy image by performing multiple discrete wavelet decomposition and reconstruction on the image, and proposes a feature attention module that takes into account both the global feature and the local information extraction of the image, which strengthens the network"s learning in image visual perception and detail texture. Secondly, in the process of feature extraction, a T-shaped method is proposed to obtain multi-scale image features, which expands the network"s representation ability. Finally, perform color balance on the reconstructed clear image to obtain the final restored image. A large number of experimental results in synthetic data sets and real data sets show that the network proposed in this paper has superior performance compared with other existing network models.

• State-sensitive-based Event-triggered H∞ Control for Path Tracking of Unmanned Ground Vehicle

  sun hong tao

  Available online:May 17, 2022  DOI: 10.16339/j.cnki.hdxbzkb.2022300

  Abstract(688) HTML(0) PDF(1.29 M)( 14689)

  Abstract:This paper proposes a state-sensitive event-triggered H∞ control strategy to solve the problem of unmanned ground vehicle (UGV) path tracking control under communication restriction. Firstly, the corresponding path tracking control model is established according to the dynamics of the connected vehicle. Secondly, a novel state-sensitive event-triggered communication (SS-ETC) strategy according to the state perception of path tracking in real time is proposed. Then, an event-triggered H∞ controller is designed by combining with time delay system modeling method and Lyapunov stability theory. The proposed dynamic event-triggered communication strategy based on state perception can dynamically adjust the communication threshold according to the state measurements of the control system, and effectively realize the adaptive co-design of UGV communication and control. Finally, the effectiveness of the proposed dynamic event-triggered control strategy is verified by simulation experiments.

• Implementation of Improved Sorted QR Decomposition on FPGA

  Chen jian, Zhuang yao yu, Yang dan, Zhang jun jie

  Available online:May 17, 2022  DOI: 10.16339/j.cnki.hdxbzkb.2022351

  Abstract(787) HTML(0) PDF(1.16 M)( 14713)

  Abstract:Although MIMO technology can improve the utilization rate of spectrum, multi-dimensional signal processing brings great challenges to the detection of MIMO signals. Based on the analysis of various MIMO detection algorithms, QR decomposition is selected as the research object, which is a kind of nonlinear algorithm. In order to obtain higher performance of detection, the sorted QR decomposition is further studied and propose the sorting scheme based on L1-norm. Using Matlab for performance simulation, the L1-norm sorting strategy and the L2-nrom sorting strategy have basically the same impact on MIMO system, but the L1-norm sorting strategy reduces the computational complexity. On this basis, the hardware structure of improved sorted QR decomposition by Givens rotation on FPGA is proposed. Comparing with the solution of L2-norm, the L1-norm strategy reduces at least 29.2% combinational logic resources and 32.4% register resources when calculating a single column norm in the realization of 4×4 channel matrix decomposition. Comparing with similar designs, the frequency of operating clock has been significantly improved.

• A lightweight key sharing protocol for IoT devices based on PUF

  wangzhenyu, Guo Yang, Li Shaoqing, Zeng Jianping

  Available online:May 17, 2022  DOI: 10.16339/j.cnki.hdxbzkb.2022352

  Abstract(882) HTML(0) PDF(1.02 M)( 14748)

  Abstract:With the development and application of communication networks, the Internet of Things carries the safe transmission and storage of a large amount of sensitive information. Since devices are usually small in size and resource-constrained, complex security primitives are not suitable for authentication of lightweight IoT devices. This paper proposes a lightweight anonymous key shared authentication protocol for IoT devices, which generates a shared key by the physical unclonable function(PUF) and uses security primitives such as the MASK algorithm and the Hash function. The security analysis and verification are accomplished by Ban logic and ProVerif to prove that the protocol ensures security attributes such as anonymity, non-repudiation, and forward/backward confidentiality. Compared with other protocols, this protocol has the characteristics of low computing cost, small communication overhead and storage capacity, and high security performance, which is suitable for the secure communication transmission of resource-constrained devices.

• Underwater multi-object segmentation technology based on spectral clustering with multi-feature weighting

  LIU Guangyu, CAO Yu, ZENG Zhiyong, ZHAO Enming, XING Chuanxi

  Available online:May 17, 2022  DOI: 10.16339/j.cnki.hdxbzkb.2022354

  Abstract(1124) HTML(0) PDF(1.60 M)( 14707)

  Abstract:Sonar image is seriously polluted by noise, which leads to the problem of low precision in underwater multi-target segmentation.Therefore, an underwater multi-object segmentation technique based on self-adjusting spectrum clustering combined with entropy weight method is proposed.The technology first by self-tuning spectral clustering of sonar image pixel clustering processing, make the image is divided into multiple independent area, and then according to the characteristics of complementarity and more sections of the redundancy of the statistical information entropy characteristics, brightness, contrast, long and narrow degree, entropy weight method is used to analyse the characteristics more empowerment and the optimal selection of a target area,Then the optimal target region is matched with all regions by multi-feature similarity. Finally, all target regions are segmented automatically by adaptive threshold iterative method according to the matching results of similarity. Experimental results show that there is not over-segmented of noise interference regions, and target regions segmented have higher accuracy, which verifies the effectiveness of the proposed method.

Vol, 52, No.3, 2025    

• Research on Flexural Bearing Capacity of Multi-cavity Steel Reinforced Concrete Underground Continuous Walls

  QIN Peng?，XING Yongkang，NING Jihong，YI Weijian，CHEN Renpeng

  2025,52(3):1-14, DOI:

  Abstract(8) HTML(4) PDF(33.43 M)( 2)

  Abstract:The paper elucidates the inherent limitations encountered by reinforced concrete continuous walls within engineering applications. It introduces the novel research concept of multi-cavity steel reinforced concrete （MSRC） as a potential solution for structural support in deep foundation pits， followed by a meticulous investigation into its bending performance. Experimental scrutiny was conducted through pure bending tests on two distinct variants of MSRC structures， each subjected to unique manufacturing processes. Results from these tests unveil subtle discrepancies in bearing capacity and other pertinent properties between the two structures. Moreover， both variants demonstrate susceptibility to bending failure in the pure bending tests， yet exhibit commendable ductility and late-stage load-bearing capacity. A comprehensive finite element analysis delves into the intricate interaction between steel and concrete throughout the entire bending process， revealing steel’s predominant role in accounting for over 80% of the bending capacity during the mid to late stages. Conversely， concrete primarily serves to mitigate local buckling of the steel. Analyzing the influences of concrete strength， steel yield strength， and steel content on member bending load capacity and stiffness reveals a positive correlation with all three parameters， with steel content exerting the greatest impact and concrete content the least. Additionally， concrete strength and steel content positively correlate with initial bending stiffness and stiffness during operational phases， albeit with concrete strength exerting a relatively minor effect. Steel content emerges as a significant determinant of stiffness. Conversely， the yield strength of steel exhibits a negative correlation with bending stiffness， albeit within a deviation threshold of 10%. Based on the assumption of a flat cross-section， the paper proposes a calculation formula for the bending capacity of MSRC structures， which demonstrates good agreement with experimental and finite element simulation results.

• Size Effect on Fire Behavior of Reinforced Concrete Single-story Plane Frame

  ZHANG Haiyan1，LI Guangzhou1，2，LI Qiyu1，WU Bo1?

  2025,52(3):15-28, DOI:

  Abstract(9) HTML(2) PDF(21.81 M)( 9)

  Abstract:To investigate the size effect on the fire behavior of reinforced concrete frame structures， fire tests on six single-story reinforced concrete plane frame structures with similar geometric characteristics but different scales were carried out under standard fire conditions. Then， finite element analysis and parametric studies were conducted to evaluate the effect of the column’s axial compression ratio and beam’s load ratio on the failure modes， deformation development， and fire resistance of the frame structures with different scales. The results show that there is a significant size effect on the fire resistance of geometrically similar frames under the same fire conditions and similar loading levels. The fire resistance increases as the sizes of the specimens increase， but the increasing extent is less than that predicted by the similarity （or equivalent） relationship of the fire resistance of the components proposed by previous studies. The failure mode of reinforced concrete plane frame structure under fire is greatly affected by the beam’s load ratio and the column’s axial compression ratio. When the column’s axial compression ratio is lower but the beam’s load ratio is higher， the frame structure is prone to beam failure， and otherwise it is prone to column failure. Due to the size effect on the columns being more significant than the size effect on the beams under fire， when column failure occurs in small-sized frames， beam failure may occur in large-sized frames with similar geometry and load levels.

• Study on Eccentric Compressive Mechanical Performance of New Bolt-welded Joint Composite Member of Large-span Rigid-frame CFST Arch Bridge

  YU Peng1，2，3，4，GUO Zikang1，YUN Weijing1，GUO Xiao1，2，3，4?

  2025,52(3):29-46, DOI:

  Abstract(8) HTML(5) PDF(127.19 M)( 1)

  Abstract:In the construction of large-span concrete-filled steel tube （CFST） arch bridges in complex terrain and harsh conditions， the construction of traditional welded joint connection of arch ribs is of high difficulty and unstable quality assurance. To address this， a new bolt-welded joint connection was proposed， which effectively reduced the difficulty of joint construction and ensured the quality of the joint. Furthermore， by using the rigid-frame （composite member） composed of CFST with the new bolt-welded joint and the outer reinforced concrete as the ribs of the arch bridge， the bearing capacity of the entire structure was improved， along with the adhesive property between the steel tube joint and the outer concrete， offering broad application prospect. Given the characteristic of small eccentric compression in arch ribs， this study investigates the mechanical performance of composite members with the new bolt-welded joint through eccentric compression tests. The mechanical differences between the composite members with different connection forms （welded joint and bolt-welded joint） were compared， and the finite element analysis was performed to further discuss the mechanical behaviour of composite members and effects of the design of the bolt-welded joint. The results indicate that the inner CFST of composite members primarily contributes to the bearing capacity under small eccentric compression. Increasing the amount of the reinforcements in the outer concrete can effectively improve the bearing capacity of composite members. New bolt-welded joint can provide superior joint performance for composite members while ensuring the safety of joint construction， which enhances the stability of the joint and improves the interaction with the outer concrete， further ensuring bearing capacity and improving ductility of composite members. When adopting the bolt-welded joint for CFST connections， the bolt-welded arc length ratio should be within 2.00.

• Force Transmission Mechanism and Design Method on Pier-beam Connection of I-shaped Composite Rigid Frame Bridge

  HUANG Yufan1，2，CHEN Lingjie1，WU Qingxiong1，3?，LIN Feihong1

  2025,52(3):47-59, DOI:

  Abstract(6) HTML(2) PDF(26.88 M)( 0)

  Abstract:The stress of pier-beam connections of Ⅰ-shaped steel-concrete composite rigid frame bridges is complex， the force transmission mechanism and load distribution of pier-beam joints are still unclear， and the calculation method of pier-beam joints is lacking. By comparing the test results of the pier-beam joints of theⅠ-shaped composite rigid frame bridges， the verified solid finite element calculation model is adopted. According to the stress state of each component of the pier-beam joint under the action of the axial force， bending moment and shearing force of the pier， the force transmission mechanism and load bearing ratio of the pier-beam joint are analyzed. The design calculation method of each component is established， and the trial design of the Ⅰ-shaped composite rigid frame bridge is carried out. The results show that the force transmission mechanism and path of axial force and bending moment are similar， and the shearing force transmission mechanism is different. The longitudinal beam and the transverse beam bear 45%~55% of the load transfer， respectively. Under the action of axial pressure and axial tension， the load transfer path and the load bearing proportion of the longitudinal beam change. The load directly transmitted by the longitudinal beam is mainly transmitted through the lower flange of the longitudinal beam， and the load transmitted to the transverse beam is mainly borne by the studs of the web. The design of the longitudinal beam should consider the additional stress of the pier load. The transverse beam is calculated according to the uniform load force mode of the simply supported beam. The design of the transverse beam web connector is calculated according to the load transferred to the transverse beam. The studs of the longitudinal beam web and lower flange are arranged by structural requirements. The pier-beam joint of trial design bridges meets the requirements. The finite element calculation results are consistent with the theoretical calculation results. The established pier-beam joint design method can be applied to the design of Ⅰ-shaped composite rigid frame bridges.

• Study on Automated Segmentation of Bridge Point Clouds Based on UAV Path Planning and Deep Learning

  WAN Guijun1，2，WU Weiwei3，4，WANG Haochen3，4，FENG Dongming3，4?

  2025,52(3):60-72, DOI:

  Abstract(5) HTML(3) PDF(75.73 M)( 0)

  Abstract:To promote the digitalization， intelligence， and refinement of bridge maintenance and management and ensure the safe operation of the bridge， an automated bridge-point-cloud segmentation method based on unmanned aerial vehicle （UAV） path planning and deep learning is proposed. First， the bridge structure is modeled through oblique photography， and based on the spatial information provided by the model， path planning is performed for the bridge deck， bridge side， bridge pier， and bridge bottom， respectively， to obtain a detailed path planning scheme for the entire bridge. UAV aerial photography and 3D reconstruction are carried out accordingly. Second， the method is validated through on-site experiments on actual bridges， and flying parameters such as flight altitude， heading， and lateral overlap ratio are determined based on the target resolution. A KML file is then generated and imported into the UAV to reconstruct the bridge’s 3D point cloud model with millimeter-level accuracy. Finally， a point cloud semantic segmentation dataset is created， and the point cloud data is divided into four categories： background， bridge deck， bridge pier， and cap beam. The lightweight and efficient RandLA-Net algorithm is used for semantic segmentation of the bridge components， achieving a mean intersection over union （MIoU） value of 98.77% and IoU values of over 95.46% for each category of components， verifying the validity of the selected algorithm on bridge point cloud segmentation.

• Identification of Heavy Vehicle on Bridge Based on Image Scene Classification and Envelope Extraction

  YAN Yongyi1，2，LIN Junping1，GAO Ke1，3?，WENG Shun1，3，ZHAO Danyang1，ZHANG Jingqi1，3

  2025,52(3):73-81, DOI:

  Abstract(4) HTML(1) PDF(13.80 M)( 7)

  Abstract:Heavy vehicle loads on urban bridges are one of the main reasons for the deterioration and damage of bridge performance. Traditional motion target detection algorithms suffer from a decrease in detection accuracy due to camera shake. This paper proposes a heavy vehicle recognition method based on the maximum structural similarity of images. A bridge field of view background model was established based on the time-domain median method， and the detected image and background model were divided into blocks. By searching for the maximum structural similarity near the corresponding block， this parameter is used as the basis for foreground/background classification to reduce the impact of camera shake. Fast Fourier transform algorithm was used to improve search speed for maximum structural similarity. Based on the vehicle’s outer envelope of a rectangular outer contour， the vehicle’s length， width， and height parameters were extracted， and sets of thresholds for heavy vehicle detection were set. The effectiveness of the proposed method was verified through the video of a certain elevated bridge. The results showed that， even with significant camera shake， the proposed method can still accurately identify heavy vehicles.

• Prediction of Fluctuating Pressure Time Series of Low-rise Buildings Based on Improved Empirical Mode Decomposition and BiLSTM Nueral Networks

  QIU Ye，YUAN Youming，SAN Bingbing?

  2025,52(3):82-93, DOI:

  Abstract(4) HTML(2) PDF(22.57 M)( 0)

  Abstract:To solve the problem of intermittent missing sensor data in wind pressure measurements， a method for predicting the wind pressure time series on the surface of structures by combining the improved empirical mode decomposition algorithm （IEMD） with bidirectional long short-term memory （BiLSTM） networks is proposed. First of all， intrinsic mode functions （IMFs） are obtained through the adaptive decomposition of wind pressure time series using the IEMD method with soft sifting stopping criterion. The sample entropy is adopted to reconstruct IMFs and obtain subsequences. Then， BiLSTM networks are established and trained with these subsequences， while the prediction is also conducted， in which the Bayesian algorithm is employed to optimize the hyperparameters of neural networks. Finally， a case study of wind load prediction based on the wind tunnel test data of low-rise buildings is conducted to validate the proposed model. The results show that， compared with the traditional prediction models （e.g. multi-layer perceptron， BiLSTM）， the prediction model based on IEMD and BiLSTM presents higher accuracy and calculation efficiency， which is capable of predicting Gaussian and non-Gaussian wind pressure signals.

• Fractal Characteristics of Measured Wind Pressures on Roof Surface of Low-rise Buildings under Typhoon Climate

  CUI Bingchang，HUANG Peng?

  2025,52(3):94-102, DOI:

  Abstract(3) HTML(3) PDF(14.37 M)( 0)

  Abstract:The loss of life and property caused by typhoons in the southeastern coastal regions of China is mainly attributed to the destruction of low-rise buildings. Therefore， analyzing the wind pressure characteristics on the roof surface under strong winds is of practical value in wind engineering. Based on the fractal theory of physics， this study conducts the fractal analysis of wind pressure pulse signals. The wind pressure and referenced wind velocity data were collected during Typhoon “Muifa” in 2011 from the Pudong experimental base of Tongji University. In the fractal analysis， the box-counting method was used to estimate the fractal dimension value for each wind pressure sample. In the result section， an example is given to demonstrate the positive correlation between fractal dimension values and the fluctuation strength of wind pressure. Then， the fractal characteristics of wind pressures on the entire roof region and the influence of roof pitches and inflow directions on the fractal dimension were investigated. Firstly， the results indicate that the wind pressures under typhoon climate are anti-persistent time series， and the mean fractal dimension for wind pressures on the entire roof region is 1.700. Secondly， the roof pitch and inflow direction affect the fractal characteristics significantly. Thirdly， the peak region of the fractal dimension appears in the area far away from the incoming flow and close to the mountain wall， while local low values occur in the central area of the roof ridge. An analysis is carried out on the correlation between the fractal characteristics and the Non-Gaussian features. The negative correlation between fractal dimension and kurtosis coefficient is strong， with a negative correlation coefficient of -0.509 under case A-00.

• Study on Unit Division Method of Ultra-long Isolated Structures During Construction Period Based on Probability

  ZHANG Chao1，DU Yongfeng1，2?，HONG Na1，XU Jun3，ZHOU Jinliang3，MA Zhenhe3，LI Chao3

  2025,52(3):103-118, DOI:

  Abstract(3) HTML(2) PDF(25.09 M)( 0)

  Abstract:The ambient temperature variation and drying shrinkage of concrete experienced by ultra-long isolated structures have certain regional and random characteristics. The probability method is used to study the unit division method of ultra-long isolated structures during the construction period to effectively control the thermal shrinkage deformation of the isolation layer. Firstly， the unit division mechanism of ultra-long isolated structures during the construction period is studied， and the control method of the thermal shrinkage deformation of the isolation layer is proposed. Secondly， based on the generalized extreme value distribution model， the optimal distribution model parameters of mean minimum temperature of the coldest month， mean temperature of the hottest month and annual average relative humidity in 12 high-intensity cities with different ambient temperature and humidity distributions are calculated. Combined with the three ambient temperature and humidity levels proposed for the construction period of ultra-long isolated structures， the recommended values of comprehensive temperature difference in 12 cities under different levels is given. Furthermore， the calculation method of the maximum setting spacing of the post-pouring belt is proposed. Then， the unit division method of ultra-long isolated structures during the construction period is summarized. Finally， the optimization analysis of unit division scheme of an ultra-long isolated structure under construction is carried out. The results show that under the condition that the stiffness generation time of the isolation layer is constant and the concrete dry shrinkage mode is determined， to ensure that the maximum thermal shrinkage deformation of the isolation layer in the synthetic direction is controlled within the limit of 55 mm， the temperature of the isolation layer in the coldest month needs to be raised to -4 °C and above when the post-pouring belt division scheme 3 and the closed scheme 1 can be adopted. To ensure the integrity of the structure and the convenience of construction， the post-pouring belt division scheme 2 and the closed scheme 1 can be adopted， and the temperature of the isolation layer in the coldest month needs to reach -1 °C and above.

• Study on Cumulative Damage Effects of Reinforced Concrete Structure under Double Internal Explosions

  DENG Peng1，2，YANG Wenxi1，HU Shijun1?，ZHANG Duo3，ZHANG Chao1，2，CHEN Renpeng1，2

  2025,52(3):119-128, DOI:

  Abstract(6) HTML(2) PDF(30.03 M)( 1)

  Abstract:Reinforced concrete structures are common forms of building structures， and the study of the damage effects of internal explosions is of great practical significance. In this study， the accuracy of the finite element modeling method for reinforced concrete structure was validated by comparing its predictions with the experimental data. Based on this method， a 2/3 scaled finite element model of a reinforced concrete shear wall structure was established to analyze the damage patterns and dynamic response of the top slab and shear wall components under two separate explosions in different rooms， as well as the cumulative damage development patterns after two successive explosions. The study reveals that： under the two separate explosions of 1kg TNT， the damage mainly occurs along the plastic hinge line of the top slab and at the connection supports of the wall and slab. The damage degree， displacement and acceleration of the top slab are significantly higher than that of the shear wall. The peak displacements at the center of the top slab in Room 2 and Room 3 reach 41.5 mm and 63.1 mm， respectively， with residual displacements of 32.2 mm and 46.1 mm. Under successive explosions in two rooms， for the slabs with lower strength and greater initial damage， the cumulative damage under the two successive internal explosions is significantly higher than the linear superposition of damages from two separate explosions. The peak displacements of the top slab center in Room 2 and Room 3 are 133.6% and 24.9% higher， and the residual displacements are 144.6% and 29.4% higher， respectively， indicating the necessity to consider cumulative damage effects. However， for the wall components with higher strength and weaker initial damage， the cumulative damage caused by the successive explosions is slightly higher than the linear superposition of damages from two separate explosions. They can be considered approximately equal， which means the cumulative damage can be neglected.

• Numerical Analysis on Seismic Performance of Base-suspended Pendulum Isolation Structure

  LU Liang1?，YIN Minghao1，XIA Wanqiu1，WANG Lei1，ZHANG Shiyu2

  2025,52(3):129-140, DOI:

  Abstract(5) HTML(4) PDF(18.25 M)( 0)

  Abstract:Base-suspended pendulum isolation （BSPI） structure is a new type of suspension isolated structural system. Firstly， the configuration of the suspension isolation layer and mechanical model of the BSPI structure are described. Then， the finite element modeling of BSPI structure is verified through comparing with the shaking table test. Finally， the finite element models of the BSPI structure and conventional frame structure are built， and dynamic structural responses of these models are analyzed by performing time-history analysis under different seismic actions. Research results indicate that the lateral stiffness of the BSPI structure is reduced greatly by installing the suspension layer， and the acceleration response of BSPI structure is significantly reduced under rare earthquakes， which is only 1/5~1/2 of that of a conventional frame. The displacement response of BSPI structure can be effectively controlled by dampers， and it is reduced to 50% of that of uncontrolled BSPI structure under rare earthquakes. The interlayer displacement of the upper structure of controlled BSPI structure is less than 1/100， which meets the seismic fortification goal.

• Calculation Approach of Bearing Ring Resistance of Tunnel Surrounding Rock in Soft Strata

  SU Ya1，SU Yonghua2，3?，LIU Yangyang2，LI Ming2，LUO Biao2

  2025,52(3):141-150, DOI:

  Abstract(6) HTML(1) PDF(11.93 M)( 1)

  Abstract:In weak strata， the mechanical effect of tunnel anchoring and shotcrete support primarily results in the formation of a bearing ring based on the surrounding rock near the spatial boundary. Based on the corresponding relationship between the relevant factors in rock mass rating （RMR） system and the factors involved in geological strength index （GSI） of rock mass， concise ways to quantify sub-items of GSI and determine its total value were obtained. Based on the equivalent conversion relationship between the internal friction angle， cohesion force and Hoek-Brown （H-B） constants of rock mass as well as the sliding failure mode of Rabcewicz’s shear wedge， calculation approaches of the bearing ring resistance and its safety factor equivalent to H-B yield criterion were established. The case study results indicate that the safety factor of the bearing ring analyzed based on the H-B criterion is consistent with its actual state， while the safety factor based on the Mohr Coulomb （M-C） criterion is too conservative. The mechanical mechanism and overall characteristics of the bearing ring are determined by the mechanical properties of its rock mass itself and the support structure constituted by rock bolts and shotcrete and steel ribs. The thickness of the bearing ring is determined by the length of rock bolts. The resistance of the bearing ring is first positively correlated with the length of rock bolts， and after exceeding a certain value， it becomes negatively correlated. The main effectiveness of steel ribs is to avoid excessive deformation and loosening of surrounding rocks in the early stages. Shotcrete is the main source of bearing ring tightening force （confining pressure）. The mechanical properties of rock mass are the dominant factor for the magnitude of bearing ring resistance.

• ESF Elastoplastic Model for Saturated Soft Clay and Model Validation

  XU Riqing1，2，YU Tianci1，WU Mingming3，ZHANG Gangping3，JU Luying4?，XU Qiliang3

  2025,52(3):151-160, DOI:

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  Abstract:An egg-shaped yield surface elastoplastic constitutive model suitable for saturated soft clay was proposed to describe the strength and deformation characteristics of saturated soft clay and overcome the defect that the direction of the plastic strain increments at the corner of the yield surface is insufficiently defined in the traditional elastoplastic model. Firstly， the ESF elastoplastic model was formulated based on the egg-shaped function （ESF）， adopting the associated flow law and employing the plastic volumetric strain as the internal variable. By introducing a closed and smooth egg-shaped yield surface， the corner problem in the traditional yield surface form was avoided. Additionally， by adjusting the value of egg-shaped parameters， the yield surface was flexibly transformed into various forms， including bullet-shaped and elliptical forms， which reflected the dependability and universality of this model. Subsequently， the undrained stress path triaxial tests were conducted on Hangzhou saturated soft clay to investigate its mechanical characteristics. The acquired data were used to analyze the stability of the model parameters under different confining pressures. Furthermore， a comprehensive analysis of the mechanical characteristics of the soft clay was performed， and the method for determining the model parameters was clarified. Finally， the finite element program using an implicit integration algorithm was developed， and its effectiveness was demonstrated through triaxial tests conducted on Hangzhou saturated soft clay and saturated kaolin clay from relevant literature under undrained conditions. The results revealed a satisfactory agreement between the simulated and experimental data， indicating that the proposed model can reasonably describe the behavior of various types of saturated soft clay under undrained conditions.

• Dynamic Diffusion Transmission Characteristics of Stratum Reinforcement Area around Operating Subway

  CAO Yang?，ZHANG Lichao，WANG Zurui，LI Jiaofeng，TAN Zenghua

  2025,52(3):161-169, DOI:

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  Abstract:To ensure the stability of the construction and operation of subway lines in a soft stratum， the soil strength around the structure can be improved by grouting reinforcement. However， according to different reinforcement degrees， the discontinuity of the soil medium will be gradually changed， and the corresponding dynamic transmission characteristics will be changed， so the dynamic response distribution mode of the reinforced area and the surrounding stratum under the driving condition needs to be further explored. A dynamic coupling model of subway line-stratum with reinforcement area is established based on the analytical theory. The reinforced soil and the natural soil are considered as saturated porous media with different physical and mechanical properties， and the corresponding dynamic equations are derived respectively by Biot theory. The subway structure is regarded as an infinite cylindrical shell with uniform thickness， which is described by the theory of the thin-walled cylindrical shell under the torsion-free condition. According to the displacement and stress continuity conditions between interfaces of the dynamic system， the vibration equations of the above parts are combined into a set of coupled dynamic equations， and the vibration of the subway peripheral stratum containing the reinforced area is calculated， the effects of stiffness and viscous damping of the reinforcement area on the distribution and transmission of the stratum dynamic response are further compared. The results show that under the steady state action， the maximum tangential acceleration of the stratum around the subway shows a cicada-wing distribution at 30° on both sides of the structure diagonally downwards， and the maximum radial acceleration occurs in the soil in the direction of the load. Due to the harmonic characteristics of the input waveform， the acceleration decays fluctuating in the stratum， but an obvious amplification of tangential acceleration occurs in the reinforcement area. After the vibration enters the natural soil， the dynamic response is significantly attenuated by the effect of stratum damping. Increasing the stiffness of the reinforcement area is conducive to reducing the conduction of tangential acceleration， while the radial acceleration changes little， and the transmitted dynamic response increases when the viscous damping decreases.

• Study on Bonding Performance of Ultra-high Performance Concrete with Coarse Aggregate and Reinforcement Bars

  HUANG Yuan1，2?，WU Rendi1

  2025,52(3):170-179, DOI:

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  Abstract:The inclusion of coarse aggregates in ultra-high performance concrete （UHPC） can effectively address the issues of high shrinkage and high cost associated with UHPC. This study investigated the bond properties of UHPC with coarse aggregate （UHPC-CA） and steel reinforcement under flexural stress using 12 lap-spliced beam specimens in 4-point bending tests. The distribution pattern of bond stress along the length of the lap splice reinforcement has been obtained by milling a slot on the surface of the steel reinforcement and pasting strain gauges evenly. Key variables studied included coarse aggregate （CA） size， CA content， splice length， and cover depth. The specimens primarily failed in splitting. The results showed that CA affected the bond performance in two ways： it enhanced the mechanical interlock and bonding strength but also increased material inhomogeneity， which may reduce bond quality. Notably， smaller CA （5~10 mm） had a more significant impact than larger CA （10~15 mm）. Increasing CA content to 800 kg/m3 made the bond stress distribution along the splice length more uniform. Extending splice length and increasing cover depth improved bonding strength retention and post-peak performance. A formula was developed to predict splitting bond strength， aligning well with experimental findings.

• Effect of Ti-extracted Slag with Different Dechlorination Processes on Properties of Cement Paste

  WANG Shuping1?，ZHONG Jingxiong1，4，XU Yinqing1，XIN Yuntao2，Lü Xuewei1，ZENG Guanwu3

  2025,52(3):180-188, DOI:

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  Abstract:The Ti-extracted slag is a by-product of Ti-bearing blast furnace slag after further extraction of titanium， and it has potential cementitious reactivity. However， due to the presence of chloride ions， its utilization in construction is limited. Therefore， further dechlorination treatment is needed. In this study， the effect of Ti-extracted residues with different dechlorination methods on the properties of cement paste was investigated. Results showed that the addition of Ti-extracted slag can reduce the fluidity of cement paste. The presence of chloride ions can shorten the setting time of the paste， and a higher amount of the slag resulted in a shorter setting time. At the same content of the residues， the shortening degree of setting time of the slag under the different dechlorination methods was obtained as follow： non-dechlorinated slag> water-washed slag> calcined slag. No obvious change in the compressive strength of the paste was observed by adding 20% Ti-extracted slag， but further increase in the content can probably reduce the strength. Chloride ions in the Ti-extracted slag were combined in the Friedel salt of the cement paste. After adding Ti-extracted slag， the stretching vibration peak of the Si—O bond shifted to a lower wavenumber. 10%~20% of Ti-extracted slag in the cement paste is recommended.

• Enhancing Method for Durability of Steel Fiber Reinforced Seawater Sea Sand Mortar Specimens Based on Iron-Catechol Biomimetic Complexation Reaction

  GUO Shuaicheng，LIU Zhiyu，QUAN Jiaozhong，WEI Sibei，LIU Yeyu，ZHU Deju?

  2025,52(3):189-200, DOI:

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  Abstract:To enhance the long-term performance of steel fibers in a marine environment， this research carries out surface treatment of steel fibers based on the iron-catechol biomimetic complexation reaction to improve their rust resistance. The surface treatment of steel fibers was conducted using different immersion times （1 d， 3 d and 7 d）， varying concentrations of tannic acid solutions （25 g/L， 50 g/L and 150 g/L）， and diverse treatment temperatures （25 ℃ and 55 ℃）. The effect and mechanism of rust resistance enhancement were investigated through tensile strength and surface morphology analysis. The results indicate that the biomimetic complexation reaction effectively enhances the chloride ion corrosion resistance of steel fibers by forming a dense protective film on their surface， and improves their long-term tensile strength. Through simulated exposure tests， the long-term performance evolution of surface-treated steel fibers in seawater sea sand mortar was studied. The results reveal that the iron-catechol complexation layer can still effectively protect steel fibers in an alkaline mortar environment， enhance their long-term tensile strength. Meanwhile， tannic acid surface treatment effectively improves the long-term flexural capacity and fracture toughness of steel fiber seawater sea sand mortar specimens. This research provides new design ideas for improving the durability of steel fiber seawater sea sand mortar specimens， which can be applied in marine engineering construction.

• Experimental Investigation on Mechanical Properties of Hot-air Brazed S30403 Austenitic Stainless Steel at High Temperatures and After Cooling

  TAN Ruixin1，LOU Guobiao1，2?，TAO Yuchao1，WANG Meinan3，LI Shun3，SU Ge3

  2025,52(3):201-212, DOI:

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  Abstract:Hot air brazed stainless steel core plates made from S30403 austenitic stainless steel exhibit outstanding mechanical properties and environmental friendliness. Compared with conventional hot radiation brazing， the hot air copper brazing technology increases productivity and reduces processing costs by more than 30%. Stainless steel is subjected to high speed and high temperature （1 100 °C） hot air treatment during the copper brazing furnace， which affects the mechanical properties of stainless steel. The tensile test of hot air brazed S30403 austenitic stainless steel under high temperatures and after cooling from high-temperature was carried out， and the main mechanical properties such as elastic modulus， nominal yield strength， ultimate strength， elongation after break were obtained. A calculation model of main mechanical properties at high temperatures of hot air brazed S30403 was established， and a high temperature stress-strain constitutive model was established based on the Rasmussen model. The study shows that the initial modulus of elasticity， nominal yield strength and ultimate strength of hot air brazed S30403 austenitic stainless steel at high temperatures decreases with the increasing temperature. At 900 °C， modulus of elasticity is about 39% of that at room temperature， nominal yield strength is about 20% and ultimate strength is about 10%. The cooling mode has a minimal effect on the nominal yield strength and the ultimate strength of hot-air brazed S30403 austenitic stainless steel， but it has a more significant impact on the modulus of elasticity and elongation after break.

• Experimental Investigation on Superelasticity of 7×7 NiTi Shape Memory Alloy Cables

  ZHOU Yuhao1，LIAN Ming1，2?，SU Mingzhou1，2，WANG Yankai1

  2025,52(3):213-227, DOI:

  Abstract(6) HTML(4) PDF(34.44 M)( 0)

  Abstract:This paper focuses on examining the mechanical properties of 7×7 configuration superelastic shape memory alloy （SMA） cables with a single wire diameter of 1.0 mm. The primary emphasis is on assessing their recovery capability and energy dissipation capacity. A detailed investigation on the effects of the heat treatment strategy， strain amplitude， cyclic loading， pre-training， and loading rate of the SMA cables on their mechanical performance—residual strain， energy dissipation， equivalent viscous damping ratios， strength， and stiffness—was conducted. Furthermore， the tensile strength and ultimate strain of SMA cables and SMA wire were compared by monotonic tensile tests. The results show that the SMA cable has excellent superelasticity after annealing at 400 °C for 10 min， and the strain recovery rate reaches 91.7%. Under constant strain amplitude loading and unloading training， the mechanical properties of SMA cable gradually tend to be stable， which should be considered in engineering applications. The recovery ability of SMA cable can be significantly improved by pre-training. The residual deformation of specimens without heat treatment and annealed for 10 min is reduced by 47% and 41% after pre-training， respectively. When the loading rate is greater than 5×10-4 s-1， the hysteresis loop shape of SMA cable is not sensitive to the change of loading rate. Compared with SMA wire， SMA cable has better ductility and robustness， which is suitable for providing sufficient restoring force in the case of large deformation. The test results provide experimental data support for the engineering application of SMA cables.

• Multi-semantic Model Generation Method of Wooden Architectural Heritage Built by Government in Ming and Qing Dynasties

  ZHANG Chengwen1，2，CHUN Qing1，2?，LI Pan1，HUA Quanjun1，LIN Yijie1

  2025,52(3):228-240, DOI:

  Abstract(6) HTML(3) PDF(33.89 M)( 0)

  Abstract:To improve the efficiency of modeling and analysis of wooden architectural heritage built by the government in Ming and Qing Dynasties， a parameterized method of multi-semantic model to achieve simultaneous generation of architectural and structural models is studied in this paper. Firstly， the basic components of wooden architectural heritage built by government in Ming and Qing dynasties were classified， and the information flow between building models and structural models was organized. Grasshopper was used for secondary development to complete the basic building component database. Then， the national key cultural relic protection unit，i.e. Beijing Deshengmen Arrow Tower， was used as an example， and a structural analysis model was automatically generated through the basic component database. The structural safety analysis was conducted automatically. The research results indicate that the proposed method can simultaneously generate building models for detailed display and structural models that can be directly used for computational analysis. The research results provide a theoretical and scientific foundation for the digital preventive protection of architectural heritage.