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空中（OTA）测试；无线性能测试；第五代（5G）及超5代；多入多出（MIMO）；多探头法（MPAC）；辐射两步法（RTS）；混响室加通道模拟器法（RC+CE） 1

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Effect of bond enhancement using carbon nanotubes on flexural behavior of RC beams strengthened with

《结构与土木工程前沿（英文）》 2022年 第16卷 第1期   页码 131-143 doi: 10.1007/s11709-021-0787-8

摘要： This paper studied the effect of incorporation of carbon nanotubes (CNTs) in carbon fiber reinforced polymer (CFRP) on strengthening of reinforced concrete (RC) beams. The RC beams were prepared, strengthened in flexure by externally bonded CFRP or CNTs-modified CFRP sheets, and tested under four-point loading. The experimental results showed the ability of the CNTs to delay the initiation of the cracks and to enhance the flexural capacity of the beams strengthened with CFRP. A nonlinear finite element (FE) model was built, validated, and used to study the effect of various parameters on the strengthening efficiency of CNTs-modified CFRP. The studied parameters included concrete strength, flexural reinforcement ratio, and CFRP sheet configuration. The numerical results showed that utilization of CNTs in CFRP production improved the flexural capacity of the strengthened beams for U-shape and underside-strip configurations. The enhancement was more pronounced in the case of U-shape than in the case of use of sheet strip covers on the underside of the beam. In case of using underside-strip, the longer or the wider the sheet, the higher was the flexural capacity of the beams. The flexural enhancement of RC beams by strengthening with CNTs-modified CFRP decreased with increasing the rebar diameter and was not affected by concrete strength.

关键词： RC beams     flexural     strengthening     CFRP     CNTs     finite element    

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Effect of RC wall on the development of plastic rotation in the beams of RC frame structures

Amar KAHIL, Aghiles NEKMOUCHE, Said BOUKAIS, Mohand HAMIZI, Naceur Eddine HANNACHI

《结构与土木工程前沿（英文）》 2018年 第12卷 第3期   页码 318-330 doi: 10.1007/s11709-017-0420-z

摘要：

The objective of this study is, to interpret the influence of reinforced concrete walls addition in reinforced concrete frame structures considering behavior laws that reflects the actual behavior of such structures, by means of Castem2000computer code (pushover analysis). A finite element model is proposed in this study, using the TAKEDA modified behavior model with Timoshenko beams elements. This model is validated initially on experimental model. Then the work has focused on the behavior of a RC frame with 3 levels and three bays to better visualize the behavior of plastic hinges. Once the plastic hinge control parameters are identified (plastic rotation, ultimate curvature), a strengthening by introduction of reinforced concrete walls (RC/wall) at the ends of the reinforced concrete frame (RC/frame) has been performed. The results show that these RC walls significantly improve the behavior, by a relocation of efforts towards the central part of the beams.

关键词： RC/frame     RC/wall     moment curvature     plastic rotation     plastic hinge     pushover analysis     global models    

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Experimental study on flexural behavior of ECC/RC composite beams with U-shaped ECC permanent formwork

Zhi QIAO, Zuanfeng PAN, Weichen XUE, Shaoping MENG

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1271-1287 doi: 10.1007/s11709-019-0556-0

摘要： To enhance the durability of a reinforced concrete structure, engineered cementitious composite (ECC), which exhibits high tensile ductility and good crack control ability, is considered a promising alternative to conventional concrete. However, broad application of ECC is hindered by its high cost. This paper presents a new means to address this issue by introducing a composite beam with a U-shaped ECC permanent formwork and infill concrete. The flexural performance of the ECC/RC composite beam has been investigated experimentally with eight specimens. According to the test results, the failure of a composite beam with a U-shaped ECC formwork is initiated by the crushing of compressive concrete rather than debonding, even if the surface between the ECC and the concrete is smooth as-finished. Under the same reinforcement configurations, ECC/RC composite beams exhibit increases in flexural performance in terms of ductility, load-carrying capacity, and damage tolerance compared with the counterpart ordinary RC beam. Furthermore, a theoretical model based on the strip method is proposed to predict the moment-curvature responses of ECC/RC composite beams, and a simplified method based on the equivalent rectangular stress distribution approach has also evolved. The theoretical results are found to be in good agreement with the test data.

关键词： engineered cementitious composite (ECC)     durability     ECC/RC composite beam     permanent formwork     flexural performance     theoretical method    

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Predicting the response of continuous RC deep beams under varying levels of differential settlement

M. Z. NASER, R. A. HAWILEH

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 686-700 doi: 10.1007/s11709-018-0506-2

摘要： This paper investigates the effect of differential support settlement on shear strength and behavior of continuous reinforced concrete (RC) deep beams. A total of twenty three-dimensional nonlinear finite element models were developed taking into account various constitutive laws for concrete material in compression (crushing) and tension (cracking), steel plasticity (i.e., yielding and strain hardening), bond-slip at the concrete and steel reinforcement interface as well as unique behavior of spring-like support elements. These models are first validated by comparing numerical predictions in terms of load-deflection response, crack propagation, reaction distribution, and failure mode against that of measured experimental data reported in literature. Once the developed models were successfully validated, a parametric study was designed and performed. This parametric study examined number of critical parameters such as ratio and spacing of the longitudinal and vertical reinforcement, compressive and tensile strength of concrete, as well as degree (stiffness) and location of support stiffness to induce varying levels of differential settlement. This study also aims at presenting a numerical approach using finite element simulation, supplemented with coherent assumptions, such that engineers, practitioners, and researchers can carry out simple, but yet effective and realistic analysis of RC structural members undergoing differential settlements due to variety of load actions.

关键词： concrete     continuous beams     deep beams     finite element modeling     support settlement    

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Determination of shear strength of steel fiber RC beams: application of data-intelligence models

Abeer A. AL-MUSAWI

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 667-673 doi: 10.1007/s11709-018-0504-4

摘要： Accurate prediction of shear strength of structural engineering components can yield a magnificent information modeling and predesign process. This paper aims to determine the shear strength of steel fiber reinforced concrete beams using the application of data-intelligence models namely hybrid artificial neural network integrated with particle swarm optimization. For the considered data-intelligence models, the input matrix attribute is one of the central element in attaining accurate predictive model. Hence, various input attributes are constructed to model the shear strength “as a targeted variable”. The modeling is initiated using historical published researches steel fiber reinforced concrete beams information. Seven variables are used as input attribute combination including reinforcement ratio ( ), concrete compressive strength ( ), fiber factor ( ), volume percentage of fiber ( ), fiber length to diameter ratio ( ) effective depth ( ), and shear span-to-strength ratio ( ), while the shear strength ( ) is the output of the matrix. The best network structure obtained using the network having ten nodes and one hidden layer. The final results obtained indicated that the hybrid predictive model of ANN-PSO can be used efficiently in the prediction of the shear strength of fiber reinforced concrete beams. In more representable details, the hybrid model attained the values of root mean square error and correlation coefficient 0.567 and 0.82, respectively.

关键词： hybrid intelligence model     shear strength     prediction     steel fiber reinforced concrete    

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Investigation of the parameters affecting the behavior of RC beams strengthened with FRP

Kadir SENGUN; Guray ARSLAN

《结构与土木工程前沿（英文）》 2022年 第16卷 第6期   页码 729-743 doi: 10.1007/s11709-022-0854-9

摘要： Three-point bending tests were carried out on nineteen Reinforced Concrete (RC) beams strengthened with FRP in the form of completely wrapping. The strip width to spacing ratios, FRP type, shear span to effective depth ratios, the number of FRP layers in shear, and the effect of stirrups spacing were the parameters investigated in the experimental study. The FRP contribution to strength on beams having the same strip width to spacing ratios could be affected by the shear span to effective depth ratios and stirrups spacing. The FRP contributions to strength were less on beams with stirrups in comparison to the tested beams without stirrups. Strengthening RC beams using FRP could change the failure modes of the beams compared to the reference beam. In addition to the experimental study, a number of equations used to predict the FRP contribution to the shear strength of the strengthened RC beams were assessed by using a limited number of beams available in the literature. The effective FRP strain is predicted by using test results, and this prediction is used to calculate the FRP contribution to shear strength in ACI 440.2R (2017) equation. Based on the statistical values of the data, the proposed equation has the lowest coefficient of variation (COV) value than the other equations.

关键词： carbon     glass     strengthening     shear strength     reinforced concrete beam     fiber reinforced polymer    

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Ductility improvement of GFRP-RC beams using precast confined concrete block in compression zone

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0968-8

摘要： Fiber-reinforced polymers (FRPs) have received considerable research attention because of their high strength, corrosion resistance, and low weight. However, owing to the lack of ductility in this material and the quasi-brittle behavior of concrete, FRP-reinforced concrete (FRP-RC) beams, even with flexural failure, do not fail in a ductile manner. Because the limited deformation capacity of FRP-RC beams depends on the ductility of their compression zones, the present study proposes using a precast confined concrete block (PCCB) in the compression zone to improve the ductility of the beams. A control beam and four beams with different PCCBs were cast and tested under four-point bending conditions. The control beam failed due to shear, and the PCCBs exhibited different confinements and perforations. The goal was to find an appropriate PCCB for use in the compression zone of the beams, which not only improved the ductility but also changed the failure mode of the beams from shear to flexural. Among the employed blocks, a ductile PCCB with low equivalent compressive strength increased the ductility ratio of the beam to twice that of the control beam. The beam failed in pure flexure with considerable deformation capacity and without significant stiffness reduction.

关键词： ductility     four-point bending test     glass fiber-reinforced polymer     precast confined concrete block    

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Calculation of diagonal section and cross-section bending capacity for strengthening RC structure using

Shouping SHANG , Fangyuan ZHOU , Wei LIU ,

《结构与土木工程前沿（英文）》 2009年 第3卷 第3期   页码 330-338 doi: 10.1007/s11709-009-0046-x

摘要： Because there is a great demand of reinforcement and retrofitting of aged structures nationwide, as well as the rapid development of innovative building materials, the adoption of strengthening RC structures using new inorganic materials has become possible. High-performance ferrocement laminate (HPFL) is an effective method of strengthening concrete structure. High-performance ferrocement laminate is a new type of inorganic material with the advantages such as high strength, small contraction, good bonding properties, etc. This paper introduces the formula of cross-section bending capacity for strengthening concrete beams with HPEL. A comparative analysis of experimental data, as well as the calculation of diagonal section bearing capacity of concrete members, is given.

关键词： RC beams     high-performance ferrocement laminate (HPFL)     inorganic material     reinforcement    

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Investigation of the interior RC beam-column joints under monotonic antisymmetrical load

Fei GAO, Zhiqiang TANG, Biao HU, Junbo CHEN, Hongping ZHU, Jian MA

《结构与土木工程前沿（英文）》 2019年 第13卷 第6期   页码 1474-1494 doi: 10.1007/s11709-019-0572-0

摘要： The paper presents numerical findings of reinforced concrete interior beam-column joints under monotonic antisymmetrical load. The finite element models considered compression and tension damage were calibrated by test results in terms of the load-displacement, failure modes, and strains of longitudinal steel. The emphasis was put on studying the effects of hoop reinforcement ratio in joint core and the axial compression ratio on the responses of the joints. The results show that, in addition to the truss and strut-and-tie mechanisms, the confinement mechanism also existed in the joint core. A certain amount of stirrup is not only able to enhance the confinement in joint core, undertake a part of shear force and thus to increase the shear capacity, prevent the outward buckling of steel bars in column, improve the stress distribution in joint core, delay cracking and restrain the propagation of cracks, but also to increase the yield load, decrease the yield displacement of beam and improve the joint ductility. However, excessive horizontal stirrups contribute little to the joint performance. In a certain range, larger axial compression ratio is beneficial for the joint mechanical behavior, while it is negative when axial compression ratio is too large.

关键词： RC beam-column joint     reinforcement ratio in joint core     axial compression ratio     finite element     test    

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Applying the spectral stochastic finite element method in multiple-random field RC structures

Abbas YAZDANI

《结构与土木工程前沿（英文）》 2022年 第16卷 第4期   页码 434-447 doi: 10.1007/s11709-022-0820-6

摘要： This paper uses the spectral stochastic finite element method (SSFEM) for analyzing reinforced concrete (RC) beam/slab problems. In doing so, it presents a new framework to study how the correlation length of a random field (RF) with uncertain parameters will affect modeling uncertainties and reliability evaluations. It considers: 1) different correlation lengths for uncertainty parameters, and 2) dead and live loads as well as the elasticity moduli of concrete and steel as a multi-dimensional RF in concrete structures. To show the SSFEM’s efficiency in the study of concrete structures and to evaluate the sensitivity of the correlation length effects in evaluating the reliability, two examples of RC beams and slabs have been investigated. According to the results, the RF correlation length is effective in modeling uncertainties and evaluating reliabilities; the longer the correlation length, the greater the dispersion range of the structure response and the higher the failure probability.

关键词： uncertainty     spectral stochastic finite element method     correlation length     reliability assessment     reinforced concrete beam/slab    

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Estimation of relations among hysteretic response measures and design parameters for RC rectangular shear

A. ARAB, Ma. R. BANAN, Mo. R. BANAN, S. FARHADI

《结构与土木工程前沿（英文）》 2018年 第12卷 第1期   页码 3-15 doi: 10.1007/s11709-017-0418-6

摘要： Seismic design of RC structures requires estimation of structural member behavioral measures as functions of design parameters. In this study, the relations among cyclic behavioral measures and design parameters have been investigated for rectangular RC shear walls using numerical simulations calibrated based on the published laboratory tests. The OpenSEES numerical simulations modeling of plastic hinge hysteretic behavior of RC shear walls and estimation of empirical relations among wall hysteretic indices and design parameters are presented. The principal design parameters considered were wall dimensions, axial force, reinforcement ratios, and end-element design parameters. The estimated hysteretic response measures are wall effective stiffness, yield and ultimate curvatures, plastic moment capacity, yield and ultimate displacements, flexural shear capacity, and dissipated energy. Using results of numerous analyses, the empirical relations among wall cyclic behavioral measures and design parameters are developed and their accuracy is investigated.

关键词： RC wall hysteretic measures     RC wall design parameters     empirical relations     numerical simulations     RC rectangular wall plastic hinge    

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Numerical simulation and analysis for collapse responses of RC frame structures under earthquake

Fuwen ZHANG, Xilin LU, Chao YIN,

《结构与土木工程前沿（英文）》 2009年 第3卷 第4期   页码 364-369 doi: 10.1007/s11709-009-0061-y

摘要： In this paper, a discrete element model for collapse simulation of RC frame structure is constructed by discretizing the structure into a few elements and spring groups. This model introduces special hysteretic models of connected springs for arbitrary loading path and also takes into account reasonable failure criteria for springs considering coupling effect of shear and axial force. Based on the discrete element model, a computer program is developed to simulate the whole process of RC frame structures from initial state to collapse under earthquakes. Particularly, the contact-impact problem between discrete elements has been treated with effective measures. Then, the program is employed to study the collapse mechanism of a real building in Wenchuan earthquake-hit area; the result of which shows that the simulation program developed based on the new model can realistically simulate the seismic collapse process of RC frame structures.

关键词： discrete element method     failure criteria     contact-impact     simulation program    

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Limit of axial force ratio and requirement for stirrups of RC columns with special shape

WANG Yiqun, XU Yidong, ZHAO Yanjing, CHEN Yunxia

《结构与土木工程前沿（英文）》 2007年 第1卷 第2期   页码 176-181 doi: 10.1007/s11709-007-0019-x

摘要： Thousands of columns with special shape are analyzed by nonlinear numerical methods. The ductility is calculated to investigate the limit of the axial force ratio and circumstantial requirement for stirrups of an reinforced concrete (RC) column with special shape, in the point of view of the characteristic value for providing stirrup. The limit of the axial force ratio of columns with special shape in relation to the characteristic value of the stirrup is obtained. Then, the effect of stirrup arrangement on the ductility of the RC column is discussed in case of buckling of the longitudinal reinforcement and constraint concrete columns. The complete requirement for stirrups of RC column with special shape is given.

关键词： reinforced concrete     circumstantial requirement     buckling     stirrup     longitudinal reinforcement    

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Investigation on modeling parameters of concrete beams reinforced with basalt FRP bars

Jordan CARTER, Aikaterini S. GENIKOMSOU

《结构与土木工程前沿（英文）》 2019年 第13卷 第6期   页码 1520-1530 doi: 10.1007/s11709-019-0580-0

摘要： Fiber-reinforced polymer (FRP) bars are widely used as internal reinforcement replacing the conventional steel bars to prevent from corrosion. Among the different types of FRP bars, basalt FRP (BFRP) bars have been used in different structural applications and, herein, three already tested concrete beams reinforced with BFRP bars are analyzed using three-dimensional (3-D) finite element analysis (FEA). The beams were tested in four-point bending. In the FEA the behavior of concrete is simulated using the “Concrete-Damaged Plasticity” model offered in ABAQUS software. The research presented here presents a calibrated model for nonlinear FEA of BFRP concrete beams to predict their response considering both the accuracy and the computational efficiency. The calibration process showed that the concrete model should be regularized using a mesh-dependent characteristic length and material-dependent post-yield fracture and crushing energies to provide accurate mesh-size independent results. FEA results were compared to the test results with regard to failure load and crack patterns. Both test the results and the numerical results were compared to the design predictions of ACI 440.1R-15 and CSA S806-12, where CSA S806-12 seems to overestimate the shear strength for two beams.

关键词： basalt Fiber-reinforced polymer bars     reinforced concrete beams     finite element analysis     damaged plasticity model     design codes    

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Multi-harmonic forced vibration and resonance of simple beams to moving vehicles

《结构与土木工程前沿（英文）》   页码 981-993 doi: 10.1007/s11709-023-0979-5

摘要： This study modeled the moving-vehicle-induced forcing excitation on a single-span prismatic bridge as a multiple frequency-multiplication harmonic load on the modal coordinates of a linear elastic simple Euler–Bernoulli beam, and investigated the forced modal oscillation and resonance behavior of this type of dynamic system. The forced modal responses consist of multiple frequency-multiplication steady-state harmonics and one damped mono-frequency complementary harmonic. The analysis revealed that a moving load induces high-harmonic forced resonance amplification when the moving speed is low. To verify the occurrence of high-harmonic forced resonance, numerical tests were conducted on single-span simple beams based on structural modeling using the finite element method (FEM) and a moving sprung-mass oscillator vehicle model. The forced resonance amplification characteristics of the fundamental mode for beam response estimation are presented with consideration to different end restraint conditions. The results reveal that the high-harmonic forced resonance may be significant for the investigated beams subjected to vehicle loads moving at specific low speeds. For the investigated single-span simple beams, the moving vehicle carriage heaving oscillation modulates the beam modal frequency, but does not induce notable variation of the modal oscillation harmonic structure for the cases that vehicle of small mass moves in low speed.

关键词： forced vibration     linear Euler beam     moving load     harmonic structure     frequency modulation     end restraints    

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标题 作者 时间 类型 操作

Effect of bond enhancement using carbon nanotubes on flexural behavior of RC beams strengthened with

期刊论文

Effect of RC wall on the development of plastic rotation in the beams of RC frame structures

Amar KAHIL, Aghiles NEKMOUCHE, Said BOUKAIS, Mohand HAMIZI, Naceur Eddine HANNACHI

期刊论文

Experimental study on flexural behavior of ECC/RC composite beams with U-shaped ECC permanent formwork

Zhi QIAO, Zuanfeng PAN, Weichen XUE, Shaoping MENG

期刊论文

Predicting the response of continuous RC deep beams under varying levels of differential settlement

M. Z. NASER, R. A. HAWILEH

期刊论文

Determination of shear strength of steel fiber RC beams: application of data-intelligence models

Abeer A. AL-MUSAWI

期刊论文

Investigation of the parameters affecting the behavior of RC beams strengthened with FRP

Kadir SENGUN; Guray ARSLAN

期刊论文

Ductility improvement of GFRP-RC beams using precast confined concrete block in compression zone

期刊论文

Calculation of diagonal section and cross-section bending capacity for strengthening RC structure using

Shouping SHANG , Fangyuan ZHOU , Wei LIU ,

期刊论文

Investigation of the interior RC beam-column joints under monotonic antisymmetrical load

Fei GAO, Zhiqiang TANG, Biao HU, Junbo CHEN, Hongping ZHU, Jian MA

期刊论文

Applying the spectral stochastic finite element method in multiple-random field RC structures

Abbas YAZDANI

期刊论文

Estimation of relations among hysteretic response measures and design parameters for RC rectangular shear

A. ARAB, Ma. R. BANAN, Mo. R. BANAN, S. FARHADI

期刊论文

Numerical simulation and analysis for collapse responses of RC frame structures under earthquake

Fuwen ZHANG, Xilin LU, Chao YIN,

期刊论文

Limit of axial force ratio and requirement for stirrups of RC columns with special shape

WANG Yiqun, XU Yidong, ZHAO Yanjing, CHEN Yunxia

期刊论文

Investigation on modeling parameters of concrete beams reinforced with basalt FRP bars

Jordan CARTER, Aikaterini S. GENIKOMSOU

期刊论文

Multi-harmonic forced vibration and resonance of simple beams to moving vehicles

期刊论文