908 research outputs found
Experimental and Numerical Characterization of the Dynamic Behaviour of a Historic Suspension Footbridge
No full textThis paper investigates the dynamic characteristics and behavior of a historic suspension footbridge through experimental and numerical studies. Ambient vibration tests were performed on the footbridge to extract the modal parameters of the structure such as natural frequencies, damping ratios, and mode shapes. The modal properties were identified from ambient vibration tests adopting the Stochastic Subspace Identification (SSI) technique. The availability of a numerical model reproducing accurately the dynamic characteristics of the footbridge is essential to carry out numerical studies on the footbridge under different dynamic loading scenarios. Due to the lack of the original technical drawings of the footbridge, a geometrical survey was carried out in order to determine the geometric characteristics of the structural elements. Furthermore, the deformed configuration of the main cable under dead load was experimentally measured during the field survey. The results of field vibration tests were used to calibrate and validate the numerical model of the footbridge, e.g., boundary conditions, and initial cable tension. The present study reports the results of the geometrical survey, of the operational modal analysis, and of the numerical modeling of the footbridge. Moreover, the 3-D Finite Element Model of the footbridge and its calibration with respect to ambient vibration tests are reported. After calibration of the finite element model, a good agreement was observed between computed and measured natural frequencies and mode shapes
Dynamic characterization and vibration serviceability assessment of a historic suspension footbridge
No full textHuman-induced vibrations of floors: A probabilistic approach
No full textThe current design guidelines for assessing floor vibration performance rely on a simplified approach that considers a single pedestrian as a fixed load with multiple harmonic components applied to the anti-nodes of the floor mode shapes. However, these guidelines do not account for the influence of variability in the walking path on the dynamic response of floors. Moreover, the deterministic approaches used in these guidelines may yield unreliable estimates of vibration response due to the stochastic nature of pedestrian walking force. The aim of this paper is to investigate the dynamic response of floors under a single pedestrian walking load while considering the randomness of the walking path and the walking load itself. A probabilistic perspective is adopted to analyze the dynamic response under different random loading scenarios. Furthermore, the effectiveness of the current guidelines in predicting the dynamic response of floors is critically assessed.
The importance of incorporating probabilistic approaches is emphasized to achieve a more comprehensive understanding of the vibration serviceability of floors and to enhance design practices in this context
Dynamic response of floors induced by a single walking pedestrian including walking path variability
No full textThis paper proposes a general non-dimensional closed-form solution to calculate the dynamic response of simply supported rectangular floors crossed by a single pedestrian schematized as a deterministic moving multi-harmonic load. The critical walking paths, which can provide the maximum vibration response, are identified and then a simplified approximated closed-form solution for the dynamic response due to a moving resonant harmonic load along the critical walking paths is proposed. Finally, the accuracy of simplified methods suggested by current guidelines is investigated by comparing the maximum non-dimensional acceleration response obtained from design guidelines with the corresponding value calculated by the analytical solution
DAWET BAYAT DAN POHON AREN DALAM BUSANA VINTAGE
No full textThe creation of this Final Project is titled “Dawet Bayat and Palm Trees in Vintage” is a from of ideas and appreciation developed by individuals with the aim of understanding the concept of making batik motifs by taking a dawet Bayat idea. The process and embodiment of batik works with dawet Bayat batik motif with remasol color substances, which are processed by individuals to create batik that has an aesthetic value and feelings from the author conveyed to the connoisseur of work, and as well as being the urge to keep the author. Dawet Bayat and plam trees are the art value in a work of batik motif can be channeled directly to the community, especially the people in the Bayat area. Everything is poured directly by the author into Batik art works and visual art to be a work that is acceptable to the public, and the creation of batik works that have difference from batik spread in Indonesia. The media used in fashion is the cotton cloth. This work realization process uses a method of creation that can help the process of work. Creation methods include data collection, data analysis, work designer, and labor embodiment. In the embodiment this final task, it makes 4 works, the entire collection of works is called “Dawet Wigunani” which is inspired by the Dawet Bayat and palm tree
A novel proficient and sufficient intensity measure for probabilistic analysis of skewed highway bridges
No full textIn this paper, a new intensity measure of earthquakes for probabilistic seismic analysis is presented for skewed highway bridges. Three different cases of skewed bridges with different skew angles (0°, 30° and 45°) are considered. Well-known intensity measures (e.g., PGA, Sa) are evaluated and critically discussed based on sensitivity analysis: efficiency, practically, proficiency and sufficiency of intensity measures are considered in detail. The analyses demonstrated that the intensity measures have to take into account structural acceleration on a wide range of periods so that a new seismic intensity measure is proposed showing that it has less dispersion compared to others. Since the proposed intensity represents the average value of the Sa (between a lower and upper structural period) it has been called Averaged Spectral Acceleration (ASA). Based on performed incremental dynamic analysis (IDA), the seismic analytical fragility curves of typical skewed highway bridges have been evaluated for different states of damage controlling the low dispersion of the ASA index as well as its proficiency and sufficiency
The effect of different intensity measures and earthquake directions on the seismic assessment of skewed highway bridges
No full textIn this study the probable seismic behavior of skewed bridges with continuous decks under earthquake excitations from different directions is investigated. A 45° skewed bridge is studied. A suite of 20 records is used to perform an Incremental Dynamic Analysis (IDA) for fragility curves. Four different earthquake directions have been considered: -45°, 0°, 22.5°, 45°. A sensitivity analysis on different spectral intensity meas ures is presented; efficiency and practicality of different intensity measures have been studied. The fragility curves obtained indicate that the critical direction for skewed bridges is the skew direction as well as the longitudinal direction. The study shows the importance of finding the most critical earthquake in understanding and predicting the behavior of skewed bridges
Probabilistic sensitivity analysis of multi-span highway bridges
No full textIn this study, we try to compare different intensity measures for evaluating nonlinear response of bridge structure. This paper presents seismic analytic fragility of a three-span concrete girder highway bridge.
A complete detail of bridge modeling parameters and also its verification has been presented. Fragility function considers the relationship of intensities of the ground motion and probability of exceeding certain
state of damage. Incremental dynamic analysis (IDA) has been subjected to the bridge from medium to strong ground motions. A suite of 20 earthquake ground motions with different range of PGAs are used in
nonlinear dynamic analysis of the bridge. Complete sensitive analyses have been done on the response of bridge and also efficiency and practically of them are studied to obtain a proficient intensity measure for
these types of structure by considering its sensitivity to the period of the bridge. Three dimensional finite element (FE) model of the bridge is developed and analyzed. The numerical results show that the bridge
response is very sensitive to the earthquake ground motions when PGA and Sa (Ti, 5%) are used as intensity measure (IM) and also indicated that the failure probability of the bridge system is dominated by the bridge
piers
Vibration Serviceability Assessment of a Historic Suspension Footbridge
No full textExperimental and numerical studies for the structural and vibration serviceability assessment of a historic suspension footbridge adopting non-invasive surveys and low-cost equipment are presented. Field surveys have been carried out to determine geometric properties, ambient vibration tests have been performed to estimate the dynamic properties, and the dynamic response of the footbridge under the action of a single crossing pedestrian has been recorded. Based on field surveys, a 3D Finite Element model was built and was then calibrated against ambient vibration test results. The experimentally-measured maximum acceleration under the action of one crossing pedestrian is compared with the ones obtained numerically and analytically. Furthermore, vibration serviceability assessment under multi-pedestrian loading is carried out, adopting the simplified procedure recommended by a recent guideline. Results show that low-cost non-invasive dynamic testing is suitable to correctly identify the footbridge vertical natural frequencies and mode shapes, including higher-order ones, and to draw considerations about the state of degradation of the structure. Moreover, the level of vibration under the action of a single pedestrian can be estimated with sufficient accuracy using a simplified loading model, provided that the modal damping ratio is properly tuned
Vibration Serviceability Assessment of a Historic Suspension Footbridge
No full textExperimental and numerical studies for the structural and vibration serviceability assessment of a historic suspension footbridge adopting non-invasive surveys and low-cost equipment are presented. Field surveys have been carried out to determine geometric properties, ambient vibration tests have been performed to estimate the dynamic properties, and the dynamic response of the footbridge under the action of a single crossing pedestrian has been recorded. Based on field surveys, a 3D Finite Element model was built and was then calibrated against ambient vibration test results. The experimentally-measured maximum acceleration under the action of one crossing pedestrian is compared with the ones obtained numerically and analytically. Furthermore, vibration serviceability assessment under multi-pedestrian loading is carried out, adopting the simplified procedure recommended by a recent guideline. Results show that low-cost non-invasive dynamic testing is suitable to correctly identify the footbridge vertical natural frequencies and mode shapes, including higher-order ones, and to draw considerations about the state of degradation of the structure. Moreover, the level of vibration under the action of a single pedestrian can be estimated with sufficient accuracy using a simplified loading model, provided that the modal damping ratio is properly tuned
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