Buildings

18 pages, 5589 KiB

Open AccessArticle

Study on the Constitutive Model of Concrete Confined by Multi-Spiral Composite Stirrups

by Kun Yang, Tao Yu, Guiliang Ma, Jiaxiang Zhao and Shanshan Sun

Buildings 2022, 12(12), 2179; https://doi.org/10.3390/buildings12122179 - 9 Dec 2022

Cited by 1 | Viewed by 1790

Through axial compression tests, the influence of three stirrup indexes (space, form, and strength) on the confining performance of multi-spiral composite stirrups in square reinforced concrete (RC) columns were analyzed, and the square RC columns with traditional well-shaped composite stirrups were used as [...] Read more.

Through axial compression tests, the influence of three stirrup indexes (space, form, and strength) on the confining performance of multi-spiral composite stirrups in square reinforced concrete (RC) columns were analyzed, and the square RC columns with traditional well-shaped composite stirrups were used as the reference group. The results show that the multi-spiral composite stirrups had a positive contribution to the important indexes (bearing capacity and ductility) of the square RC columns due to its multiple restraint mechanism on core concrete. In terms of constraint effect, the five-spiral composite stirrup is the best, followed by the four-spiral composite stirrup, and the last is the traditional well-shaped composite stirrup. The section of the concrete square column is divided into highly constrained, partially constrained and unconstrained regions and the constraint mechanism of multi-spiral composite stirrups is discussed. The formulas for calculating the peak stress, peak strain, and ultimate compressive strain of the constrained column are presented, and the relative error between the theoretical values and the tested values is small. The constitutive model of concrete constrained by multi-spiral composite stirrups is established and compared with other constitutive models. The results show that the proposed model fits well with the experimental curves. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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22 pages, 8173 KiB

Open AccessArticle

Shaking Table Test of a Base-Isolated Frame Structure under Near-Fault Ground Motions

by Qing Lyu, Baijie Zhu, Wensheng Lu, Bo Fu, Liangkun Liu, Wei Qian, Ming Zhou and Zhenya Zhang

Buildings 2022, 12(12), 2258; https://doi.org/10.3390/buildings12122258 - 18 Dec 2022

Cited by 2 | Viewed by 2293

Abstract

A five-story moment frame structural model with a base isolation system was tested on a shaking table. The isolation system comprised both linear natural rubber bearing (LNR) and nonlinear viscous dampers (NLVDs). Seven ground motions were employed: including three far-fault (FF) and four [...] Read more.

A five-story moment frame structural model with a base isolation system was tested on a shaking table. The isolation system comprised both linear natural rubber bearing (LNR) and nonlinear viscous dampers (NLVDs). Seven ground motions were employed: including three far-fault (FF) and four near-fault (NF) earthquake ground motions. The performance of the isolation system was evaluated by measuring the displacement and base shear of the isolation bearings. Furthermore, the axial force and displacement of the NLVDs were measured. The evolution of the fundamental dynamic frequency of the frame during the test was also determined. During strong earthquakes, NF ground motions caused larger story drifts and floor accelerations of the superstructure than FF ground motions. The displacement and base shear of the isolation base was very large when the isolated structure was subjected to Kobe_TAK000 and ChiChi_TCU102/278 pulse-like NF ground motions. Furthermore, the LNR s experienced tension and uplift when the PGA of input earthquake ground motions was larger than 0.80 g. Although the NLVDs performed very well in combination with the LNRs, the severe responses of the isolation bearings were caused by NF ground motion with a pulse period T_p neighboring the fundamental period of the isolated structure. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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24 pages, 10932 KiB

Open AccessArticle

Investigation on the Seismic Performance of RC Frame Buildings with Rubber Isolation Bearing Installed in Staircases

by Liang Bai, Xingwen Liang, Li Xin, Mingxiao Liu, Ziming Yu and Yage Chu

Buildings 2023, 13(3), 616; https://doi.org/10.3390/buildings13030616 - 26 Feb 2023

Viewed by 1732

Abstract

A rubber isolation bearing installed in a staircase (RBS) was proposed to mitigate seismic damages to the component of staircases and improve their seismic performance. A series of quasi-static tests performed with respect to the horizontal and vertical mechanical properties of RBS as [...] Read more.

A rubber isolation bearing installed in a staircase (RBS) was proposed to mitigate seismic damages to the component of staircases and improve their seismic performance. A series of quasi-static tests performed with respect to the horizontal and vertical mechanical properties of RBS as well as the numerical modelling were verified with experimental results. Next, the finite element models of typical types of reinforced concrete frames (without stairs, with cast-in-place reinforced concrete stairs, and with RBS stairs) were established. The modal dynamic and non-linear elasto-plastic analyses of system-level building models were herein conducted, respectively. The effect of the RBS on the dynamic response of the whole structure and the mechanical performance of stair components was revealed. The analysis results indicated that the RBS provided the desired floor-to-floor relative drift and effectively isolate the seismic action from the stair flight. Therefore, the presence of RBS can effectively mitigate the influence of a staircase on the entire building’s structure, weaken the diagonal strut effect of flights, and reduce the inner forces of staircase components. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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12 pages, 3731 KiB

Open AccessArticle

Study on VIV Behavior of Two 5:1 Rectangular Cylinders in Tandem Based on Correlation Analysis

by Kai Ma, Changyong Zhang, Xinzhi Dang and Guoquan Zhang

Buildings 2024, 14(1), 85; https://doi.org/10.3390/buildings14010085 - 28 Dec 2023

Viewed by 972

Abstract

To investigate the vortex-induced vibration (VIV) characteristics of two rectangular cylinders with a width-to-depth ratio of 5:1 in a tandem arrangement, sectional model wind tunnel tests that measure vibration responses and pressure distributions simultaneously were adopted. The ratio of the spacing between the [...] Read more.

To investigate the vortex-induced vibration (VIV) characteristics of two rectangular cylinders with a width-to-depth ratio of 5:1 in a tandem arrangement, sectional model wind tunnel tests that measure vibration responses and pressure distributions simultaneously were adopted. The ratio of the spacing between the cylinders to its width is 1.2. The analyses were performed considering VIV responses as well as the distribution characteristics of mean and rms pressure coefficients. Additionally, the time-frequency domain statistical parameters like correlation and contribution coefficients, phase lags between distributed and general vortex excited forces (VEFs), and amplitudes of VEF coefficients at predominant frequencies were calculated to analyze the physical VIV mechanism of two 5:1 rectangular cylinders in tandem. This study indicates that the influence of incidence angles on the dynamic responses is notable; the contribution of the distributed VEFs acting on the trailing surface of the upstream cylinder and the leading surface of the downstream one is significant to VIVs of the cylinders from wind pressure distribution characteristics and correlation analyses. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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16 pages, 5794 KiB

Open AccessArticle

Optimization of the Seismic Performance of a Steel-Concrete Wind Turbine Tower with the Tuned Mass Damper

by Yanchao Yue, Changxin Li, Kai Jia, Yuhang Zhang and Jingjing Tian

Buildings 2022, 12(9), 1474; https://doi.org/10.3390/buildings12091474 - 17 Sep 2022

Cited by 6 | Viewed by 2211

Abstract

To optimize the seismic performance of a new type of steel-concrete tower, a 120 m steel-concrete composite tower model with a tuned mass damper (TMD) was constructed in ABAQUS for simulation analysis. Firstly, a time history analysis was conducted to study the towers [...] Read more.

To optimize the seismic performance of a new type of steel-concrete tower, a 120 m steel-concrete composite tower model with a tuned mass damper (TMD) was constructed in ABAQUS for simulation analysis. Firstly, a time history analysis was conducted to study the towers with and without a TMD to determine the difference in their accelerations, velocities, and displacements. Then, a frequency spectrum analysis was performed to determine the tower vibration reduction effect of TMDs with different mass ratios. Five different cases were considered to explore the impact of different layouts on the dynamic performance of the tower. The results showed that the TMD had a significant vibration reduction effect on the tower accelerations, velocities, and displacements. The acceleration was reduced the most, while the vibration reduction effect in the middle of the tower was more significant than that at the top of the tower. For the steel-concrete tower studied in this paper, the optimal mass ratio of TMD was found to be 0.01. Placing one TMD at the top and another in the middle of the tower was found to be the optimal TMD arrangement for tower vibration reduction. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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17 pages, 4841 KiB

Open AccessArticle

Effect of an Innovative Friction Damper on Seismic Responses of a Continuous Girder Bridge under Near-Fault Excitations

by Junjun Guo, Huaifeng Li, Changyong Zhang, Shihyu Chu and Xinzhi Dang

Buildings 2022, 12(7), 1019; https://doi.org/10.3390/buildings12071019 - 15 Jul 2022

Cited by 4 | Viewed by 2099

Abstract

Continuous girder bridges have been extensively constructed in China over the past 30 years, and these bridges tend to experience severe damage under ground motions with velocity pulses. In the current research, an innovative linear friction damper (LFD) is proposed to mitigate the [...] Read more.

Continuous girder bridges have been extensively constructed in China over the past 30 years, and these bridges tend to experience severe damage under ground motions with velocity pulses. In the current research, an innovative linear friction damper (LFD) is proposed to mitigate the seismic damages of continuous girder bridges subjected to near-fault ground motions. The OpenSees platform is adopted to establish the numerical model of a continuous girder bridge in the near-fault region. Sixteen ground motions with velocity pulses are selected from the PEER ground motion database. The wavelet method is used to extract the maximum velocity pulse from the two orthogonal components of a ground motion. The effects of the initial gap, the coefficient of friction, and the spring stiffness of LFD on the seismic responses of the bridge are investigated by the response surface method (RSM). The seismic responses of the bridge for the original system (Non-isolated), LFD system (Isolated-LFD), and lead rubber bearing (LRB) system (Isolated-LRB), such as force–displacement relationship, bearing displacement, and pier curvature, are obtained after conducting a series of nonlinear time history analyses. The numerical results reveal that this innovative device (LFD) can effectively control the relative displacements between the superstructure and substructure of the bridge. Meanwhile, the seismic responses of the piers can be significantly decreased compared with the non-isolated system. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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18 pages, 5308 KiB

Open AccessArticle

Seismic Fragility Assessment of Cable-Stayed Bridges Crossing Fault Rupture Zones

by Junjun Guo, Yitong Gu, Weihong Wu, Shihyu Chu and Xinzhi Dang

Buildings 2022, 12(7), 1045; https://doi.org/10.3390/buildings12071045 - 19 Jul 2022

Cited by 8 | Viewed by 2514

Abstract

Current studies lack probabilistic evaluations on the performance of fault-crossing bridges. This paper conducts seismic fragility analyses to evaluate the fragility of cable-stayed bridges with the effects of fault ruptures. Synthetic across-fault ground motions are generated using existing simulation methods for the low-frequency [...] Read more.

Current studies lack probabilistic evaluations on the performance of fault-crossing bridges. This paper conducts seismic fragility analyses to evaluate the fragility of cable-stayed bridges with the effects of fault ruptures. Synthetic across-fault ground motions are generated using existing simulation methods for the low-frequency pulses and high-frequency residuals. Incremental dynamic analysis is utilized to generate the seismic responses of the bridge. The optimal intensity measure (IM) for a cable-stayed bridge that crosses a fault is identified based on the coefficient of determination (R²). Root-mean-square velocity (V_rms) is found to be the best IM for cable-stayed bridges traversed by fault ruptures, instead of the commonly used ones such as peak ground acceleration or velocity (PGA or PGV). Fragility curves for the critical components of fault-crossing cable-stayed bridges, including pylons, cables, and bearings, are developed using the IM of V_rms, and are subsequently compared with those for the cable-stayed bridge near faults. Results show that the bearings on transition piers are the most vulnerable component for fault-crossing cable-stayed bridges because of the rotation of their girder. Compared to cable-stayed bridges near faults, pylons and bearings are more vulnerable in the transverse direction for cable-stayed bridges crossing faults, whereas the vulnerability of cables is comparable. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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24 pages, 11979 KiB

Open AccessArticle

Performance Evaluation of Reinforced Concrete Columns under Simultaneously Combined Fire and Cyclic Loads

by Qingjun Chen and Yu Jiang

Buildings 2022, 12(7), 1062; https://doi.org/10.3390/buildings12071062 - 21 Jul 2022

Cited by 3 | Viewed by 2174

Abstract

Reinforced concrete (RC) structures could suffer from the combined action of fires, earthquakes, and other loads during their life cycle; more importantly, coupled disasters lead to further deterioration and damage to structural performance. This paper investigated the multiple performances and distinguished the safe [...] Read more.

Reinforced concrete (RC) structures could suffer from the combined action of fires, earthquakes, and other loads during their life cycle; more importantly, coupled disasters lead to further deterioration and damage to structural performance. This paper investigated the multiple performances and distinguished the safe working conditions of the RC column subjected to simultaneously combined fire and cyclic loads. The numerical model considered the degradation of the mechanical properties of steel and concrete and the bond-slip performance between steel and concrete at high temperatures. The results show that the performance of RC columns with different section sizes, longitudinal reinforcement ratios, cover thicknesses, axial load ratios, and cyclic loads differs greatly under simultaneously combined fire-cyclic loads. In specific, when the cyclic load application time is less than 2 h, the cyclic load has little effect on the response of the RC column. According to the different characteristics of RC columns when subjected to combined fire-cyclic loads, the firing process of RC columns is divided into four stages. To avoid the excessive performance degradation of RC columns, the minimum designed fire resistance time of RC columns is recommended to be 2.5 times the fire resistance time of the RC column under static loads. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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13 pages, 6459 KiB

Open AccessArticle

Effects of Coal Gangue Coarse Aggregate on Seismic Behavior of Columns under Cyclic Loading

by Hanqing Liu, Guoliang Bai, Fang Yan, Yu Gu and Kefan Zhu

Buildings 2022, 12(8), 1170; https://doi.org/10.3390/buildings12081170 - 5 Aug 2022

Viewed by 1937

Abstract

Coal gangue is the rock discharged from coal mining. Using coal gangue as coarse aggregate is one of the solutions for the sustainable development of construction engineering. Five one-half scaled coal gangue concrete (CGC) frame columns with different coal gangue coarse aggregate replacement [...] Read more.

Coal gangue is the rock discharged from coal mining. Using coal gangue as coarse aggregate is one of the solutions for the sustainable development of construction engineering. Five one-half scaled coal gangue concrete (CGC) frame columns with different coal gangue coarse aggregate replacement ratios were designed, and the effect of coal gangue coarse aggregate on seismic behavior of columns under cyclic loading was studied. The test results show that the failure of coal gangue coarse aggregate under cyclic loading is the main reason for the reduction in hysteretic performance of CGC specimens. Compared with natural aggregate concrete (NAC) specimen, the hysteretic behavior, deformation performance, and energy consumption of CGC columns were reduced. However, the seismic performance of CGC specimens with higher replacement ratio was better than that of CGC specimens with a lower replacement ratio. Compared with NAC specimen, the ductility and total energy dissipation of CGC specimen with r = 100% were only reduced by 8.2% and 12.8%. In addition, the test results also found that the higher the replacement ratio, the greater the shear deformation of the specimen. It is recommended to appropriately increase the stirrup ratio of CGC specimens in seismic design. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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16 pages, 5977 KiB

Open AccessArticle

Experiment Study on the Hysteretic Performance of a Novel Replaceable Beam-to-Column Joint with Energy-Dissipating Steel Hinge

by Yongchao Ma, Ai Qi, Guiyun Yan, Lianqiong Zheng and Panrong Xue

Buildings 2022, 12(8), 1180; https://doi.org/10.3390/buildings12081180 - 7 Aug 2022

Cited by 1 | Viewed by 2468

Abstract

A novel precast replaceable beam-to-column joint with energy-dissipating steel hinges was proposed for the connection of precast structures to improve the seismic performance and post-earthquake resilience. The proposed joint was installed in the predetermined plastic hinge region at beams and the flange segments [...] Read more.

A novel precast replaceable beam-to-column joint with energy-dissipating steel hinges was proposed for the connection of precast structures to improve the seismic performance and post-earthquake resilience. The proposed joint was installed in the predetermined plastic hinge region at beams and the flange segments of the proposed joint were weakened to achieve damage concentration. Cyclic loading tests were conducted on the proposed joint and the steel sleeve confined concrete joint to study the hysteretic performance, including failure mode, load–displacement curves, ductility, and energy-dissipation capacity. Moreover, the hystertic performance of the damage-repaired proposed joint was investigated to verify the post-earthquake resilience. Results demonstrated that the proposed joints could develop favorable failure mode with the necking rupture of the weakened steel plate in steel hinge. The damage of the proposed joint was concentrated in the energy-dissipating hinges while no serious damage was observed in the precast framing components, achieving the objective of damage concentration. Compared with steel sleeve confined concrete joint, the hysteresis curve of proposed joint was more plump while an obvious pinching effect was observed in the steel-confined concrete joint. The bearing capacity and energy-dissipation capacity of the proposed joint were about 1.25 times and 1.55 times of that for the steel sleeve confined concrete joint, respectively. In addition, the hysteretic performance of the repaired specimen was identical to the original one, with the desired failure mode caused by the fracture of the steel hinge. It was noted that the hysteretic performance of the repaired joint was better than the steel sleeve confined concrete joint. The bearing capacity was recovered at up to 96.6% of the original joint while the energy-dissipation capacity was recovered at 96.1%, indicating that the proposed joint achieved the post-earthquake resilience to a great extent. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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18 pages, 4743 KiB

Open AccessArticle

Aftershock Fragility Assessment of Continuous RC Girder Bridges Using a Modified Damage Index

by Zhengnan Wang, Xiaowei Deng, Xiheng Luo, Xinzhi Dang and Junjun Guo

Buildings 2022, 12(10), 1675; https://doi.org/10.3390/buildings12101675 - 12 Oct 2022

Cited by 1 | Viewed by 1710

Abstract

Aftershock fragility is usually calculated conditioned on a range of potential post-mainshock damage states. The post-mainshock damage can be identified using damage indices, the latter being frequently associated with displacement-based parameters such as the maximum drift ratio or the residual displacement. However, when [...] Read more.

Aftershock fragility is usually calculated conditioned on a range of potential post-mainshock damage states. The post-mainshock damage can be identified using damage indices, the latter being frequently associated with displacement-based parameters such as the maximum drift ratio or the residual displacement. However, when the reliable simulation of a structural system in a specific post-mainshock damage state is the objective of a numerical study, using such damage indicators may not assure the structure experiencing a homogeneous level of damage due to different mainshocks characteristics, which induce the aftershock fragility results unreliable. Along these lines, the current study presents a damage evaluation methodology mainly used for aftershock fragility assessment. It aims to reduce the variation of damage levels derived by using different mainshock seismic motions. The methodology presented herein includes: (i) the introduction of a damage index defined by comparing the monotonic pushover curve of the intact and post-earthquake damaged structure; (ii) the description of a finite element (FE)-based scheme that enables to quantify of the proposed damage index; and (iii) a deterioration-related modeling technique that can capture both strength and stiffness degrading performance of structural systems exposed to earthquake-induced excitations. The latter is essential to support the FE-based quantification scheme for the damage index. This methodology evaluation methodology can be primarily used for calculating the aftershock fragility assessment for a multi-span RC continuous girder bridge. The back-to-back incremental dynamic analysis framework uses a larger number of mainshock-aftershock artificial sequences to generate the aftershock fragility curves. The AS fragility results obtained via MBDI are compared with that via maximum drift ratio in terms of the ability to reduce the variation of residual capacities obtained using different mainshocks to induce a specific damage state but collapse by the same aftershock. The comparison shows a more robust relationship of MBDI with the residual capacity. It is found that MBDI, as well as its quantification approach proposed in this study, is a more effective damage predictor than the widely used displacement-based indices for AS fragility assessment. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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16 pages, 9868 KiB

Open AccessArticle

Feasibility Evaluation of Novel High-Damping Rubbers as Energy-Dissipation Material under Axial Dynamic Load for Damper Devices

by Tzyy Wooi Teh, Chee Ghuan Tan and Mohd Zamin Jumaat

Buildings 2022, 12(11), 1917; https://doi.org/10.3390/buildings12111917 - 7 Nov 2022

Cited by 2 | Viewed by 2024

Abstract

High-damping rubber (HDR) material has been widely used in bearings for seismic-isolation devices in structures. Nevertheless, HDR has not yet been developed in dampers to reduce the response of structures to earthquake excitations by dissipating the energy applied to the structures under direct [...] Read more.

High-damping rubber (HDR) material has been widely used in bearings for seismic-isolation devices in structures. Nevertheless, HDR has not yet been developed in dampers to reduce the response of structures to earthquake excitations by dissipating the energy applied to the structures under direct axial load. The purpose of this paper was to evaluate the feasibility of using novel hyperelastic composite material (HECM), which is an HDR material, in experimental investigations to determine its damping ratio, compressibility, and elasticity behavior under axial dynamic load for the development of novel dampers in the future. First, a series of tests on HECM was conducted using the double-shear method to determine the most suitable sample for a purely dynamic compression test. Subsequently, the HECM was used in a device working as a scaled-down damper under both direct tension and compression dynamic load conditions, and pure direct compression dynamic load conditions were tested. Various thicknesses of the HECM (6, 8, and 10 mm) used in the testing damper were examined under a constant force with various frequencies of 0.01, 0.1, 0.25, and 0.5 Hz. The results show that the 10 mm thick HECM can provide a high damping ratio of 10% to 13% under axial conditions. Hence, this study is important for evaluating HECM, which has the potential for use in developing a full-scaled rubber damper system to resist axial force in the future. The damper is a novel rubber damper with high damping capability to dissipate energy under axial load. Furthermore, the damper can serve as an alternative choice that is more durable and overcomes the current weaknesses of passive dampers. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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21 pages, 5985 KiB

Open AccessArticle

Ultimate Bearing Capacity Analysis of Pile Caps with New Socket Connections

by Jiping Ge, Luqi Lai, Side Liu and Xingfei Yan

Buildings 2022, 12(11), 2034; https://doi.org/10.3390/buildings12112034 - 21 Nov 2022

Cited by 2 | Viewed by 2360

Abstract

Socket connection need a groove reserved in the cap to accommodate a bridge pier, which greatly weaken the vertical bearing capacity of the cap. The conventional treatment measure is to increase the thickness of the cap, and the corresponding cost will increase. The [...] Read more.

Socket connection need a groove reserved in the cap to accommodate a bridge pier, which greatly weaken the vertical bearing capacity of the cap. The conventional treatment measure is to increase the thickness of the cap, and the corresponding cost will increase. The measures to enhance the vertical bearing capacity of socket caps without increasing the thickness of the cap were discussed in this paper, including a rough interface at the bottom of the pier, additional hanging bars, high-strength grouting material in the seam, and large-diameter metal corrugated pipes, etc. Based on a previous test, the finite element analysis of the vertical bearing capacity of pile caps with new socket connections was carried out. The analysis parameters included the construction method, steel bar diameter in the bottom of the cap, socket depth, thickness of the bottom plate, pile length, and friction coefficient, etc. The bearing capacity M–N relation of the full-scale model was also analyzed. Research indicated the vertical bearing capacity of the cap is mainly provided by rough interfaces, the bottom plate, and the additional hanging bars, and the contribution of the three parts was about 40%, 34%, and 26%; the vertical bearing capacity was proportional to the areas of steel bars on the cap and the thickness of the bottom plate, and was inversely proportional to the length of the pile. To obtain the vertical bearing capacity of the overall cast-in-place plan for the socket cap, the thickness of the cap needs to be increased by 27%. At last, a design formula for the calculation of the vertical bearing capacity was proposed. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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30 pages, 7669 KiB

Open AccessArticle

Effects of Vertical Ground Motion on Pedestrian-Induced Vibrations of Footbridges: Numerical Analysis and Machine Learning-Based Prediction

by Xinxin Wei, Bo Fu, Wenyan Wu and Xinrui Liu

Buildings 2022, 12(12), 2138; https://doi.org/10.3390/buildings12122138 - 5 Dec 2022

Cited by 7 | Viewed by 2823

Abstract

Current codes and guidelines for the dynamic design of footbridges often only specify the pedestrian-induced excitations. However, earthquakes may occur during the passing stage of pedestrians in earthquake-prone regions. In addition, modern footbridges tend to be slender and are sensitive to vertical ground [...] Read more.

Current codes and guidelines for the dynamic design of footbridges often only specify the pedestrian-induced excitations. However, earthquakes may occur during the passing stage of pedestrians in earthquake-prone regions. In addition, modern footbridges tend to be slender and are sensitive to vertical ground motions. Therefore, we investigate the effects of vertical ground motion on pedestrian-induced vibrations of footbridges. A total of 138 footbridges with different materials, dimensions, and structural types are considered as the target structures. The classical social force model combined with the pedestrian-induced load is used to simulate crowd loads for the scenarios with six typical pedestrian densities. Furthermore, 59 vertical ground motions with four seismic intensities are taken as the seismic inputs. An amplification factor is introduced to quantify the amplification effects of vertical ground motion on human-induced vibrations of footbridges. Four machine learning (ML) algorithms are used to predict the amplification factor. The feature importance indicates that the scaled peak ground acceleration, the pedestrian density, and the bridge span are the three most important parameters influencing the amplification factor. Finally, the vibration serviceability of the footbridge subjected to both crowd load and vertical ground motion is assessed. Full article

(This article belongs to the Special Issue Improvement Technology on Building Seismic Toughness)

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