scholarly journals Evaluation of Stiffness and Dynamic Properties of a Mine Shaft Steelwork Structure through In Situ Tests and Numerical Simulations

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 664
Author(s):  
Jacek Jakubowski ◽  
Przemysław Fiołek
Keyword(s):  
Numerical Simulations ◽  
Dynamic Properties ◽  
Vertical Motion ◽  
Load Test ◽  
Mode Shapes ◽  
Dynamic Amplification Factor ◽  
In Situ Tests ◽  
Mine Shaft ◽  
Numerical Investigations

A mine shaft steelwork is a three-dimensional frame that directs the vertical motion of conveyances in mine shafts. Here, we conduct field and numerical investigations on the stiffness and dynamic properties of these structures. Based on the design documentation of the shaft, materials data, and site inspection, the steelwork’s finite element model, featuring material and geometric non-linearities, was developed in Abaqus. Static load tests of steelwork were carried out in an underground mine shaft. Numerical simulations reflecting the load test conditions showed strong agreement with the in situ measurements. The validated numerical model was used to assess the dynamic characteristics of the structure. Dynamic linear and non-linear analyses delivered the natural frequencies, mode shapes, and structural response to dynamic loads. The current practices and regulations regarding shaft steelwork design and maintenance do not account for the stiffness of guide-to-bunton connections and disregard dynamic factors. Our experimental and numerical investigations show that these connections provide considerable stiffness, which leads to the redistribution and reduction in bending moments and increased stiffness of the construction. The results also show a high dynamic amplification factor. The omission of these features implicates an incorrect assessment of the design loads and can lead to over- or under-sized structures and ultimately to shortened design working life or failure.

scholarly journals Dynamic Identification of an Early 20th Century Civil Architectural Building

2020 ◽  
Vol 6 (4) ◽  
pp. 670-678 ◽  
Author(s):  
Bilal Muhammed Bağbancı
Keyword(s):  
Finite Element ◽  
Mechanical Test ◽  
Dynamic Properties ◽  
Mode Shapes ◽  
Finite Element Models ◽  
In Situ Tests ◽  
Historical Structures ◽  
Reinforced Concrete Slabs ◽  
Construction Techniques

Historical structures are important in terms of both original construction techniques and cultural heritage. Therefore, material properties, construction techniques and dynamic behaviors of these structures must be identified in order to preserve them in the future by restoration studies.  This study is aimed to serve as an example for similar buildings in the region whose walls were constructed using filled brick with lime mortar and constructed using both timber and reinforced concrete slabs. In this study, the plan layout, construction techniques and the material usage of the building were investigated in detail. The mechanical and dynamic properties such as compressive stress, elastic moduli, shear stress, natural frequencies and mode shapes of the building were determined in-situ by flat-jack, shear and vibration tests. The finite element model of the structure was prepared, and the modal analysis of the structure was performed. The calibration of the model was ensured according to the vibration test results. The results obtained from this study show us that in-situ tests are extremely important for the accuracy of finite element models. It has been determined that the mechanical test data can be used with over 80% success in finite element models.

scholarly journals All-GFRP footbridge under human-induced excitation

2019 ◽  
Vol 262 ◽  
pp. 10013
Author(s):  
Beata Stankiewicz ◽  
Piotr Górski ◽  
Marcin Tatara
Keyword(s):  
Dynamic Properties ◽  
Complex Problem ◽  
In Situ Tests ◽  
Critical Range ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Free Decay ◽  
Technical Guide ◽  
Pedestrian Excitation

The dynamic behavior of lively footbridge is a complex problem. Recently there were numerous publications and recommendations related to the dynamic nature of footbridge. The complicated procedure which was set in a number of instructions and standards says nothing about actions aimed at avoiding critical frequency range in structure. In the paper, results of dynamic in-situ tests of cable-stayed all-GFRP (Glass Fiber Reinforced Polymer) footbridge are presented. Fiberline Footbridge, located in Kolding city in Denmark, was constructed in 1997 using 12 different pultruded profiles all made of GFRP material. The dynamic characteristics as well as vertical response of the tested footbridge under human excitation are given and discussed. Firstly, in order to estimate the dynamic properties of the footbridge, a series of free-decay responses under human jumping were conducted. The fundamental frequency of the analyzed structure was within a critical range. A methodology for footbridge classification with regard to their dynamic sensitivity was worked out and the correlation between the structure's properties and its dynamic response under pedestrian excitation was formulated. It was found that the analyzed footbridge fulfilled vibration comfort criteria elaborated by technical guide Sétra, however, more restricted acceleration limits suggested by Eurocode were not met.

scholarly journals The Dynamic Properties of Historic Timber-Framed Masonry Structures in Bursa, Turkey

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
M. Bilal Bağbancı ◽  
Özlem Köprülü Bağbancı
Keyword(s):  
Dynamic Properties ◽  
Mode Shapes ◽  
Masonry Structures ◽  
Timber Structures ◽  
Lime Mortar ◽  
Construction Techniques ◽  
Significant Damage ◽  
Lime Mortars ◽  
Earthquake Load

Timber-framed masonry structures are known as an effective earthquake load resisting system in high seismicity regions such as Bursa, Turkey. Intense earthquakes have occurred throughout history; however, many of the traditional timber structures have been able to survive without significant damage until the present day. In this study, six historic two-storied timber-framed masonry structures dating from the nineteenth century in Bursa City are investigated by using laboratory and in situ structural health monitoring tests. Although the houses have the same construction techniques, different masonry infill materials are used inside the timber frames. Stone, adobe, and brick are used as infill materials. Mud and lime mortars are used as binding materials. Mud mortar is used with stone and adobe materials. Lime mortar is used with brick material. The physical, mechanical, and dynamic parameters such as density, specific gravity, porosity, elastic modulus, frequencies, mode shapes, and damping ratios of the studied structures were investigated and the results were comparatively discussed. It is understood that the use of different infill materials affects the dynamic behaviors of these structures.

scholarly journals Predicting the bearing capacity of pile installed into cohesive soil concerning the spatial variability of SPT data (A case study)

2021 ◽  
Vol 11 (1) ◽  
pp. 45-64
Author(s):  
Duong Hong Tham ◽  
Truong Nhu Manh
Keyword(s):  
Bearing Capacity ◽  
Static Load ◽  
Physical And Mechanical Properties ◽  
Cohesive Soil ◽  
Load Test ◽  
Penetration Test ◽  
Static Load Test ◽  
In Situ Tests ◽  
Spt Data

Nowadays, in situ tests have played a viable role in geotechnical engineering and construction technology. Besides lab tests conducted on undisturbed soil samples, many different kinds of in-situ tests were used and proved to be more efficient in foundation design such as pressuremeter PMT, cone penetration test CPT, standard SPT, etc. Among them, a standard penetration test (SPT for short) is easy to carry out at the site. For decades, it has proved reliable to sandy soil, but many viewpoints and opinions argued that the test was not appropriately applicable to cohesive soil because of scattered and dispersed data of SPT blow counts through different layers. This paper firstly studies how reliable the SPT data can predict the physical and mechanical properties; secondly, the soil strength is determined in terms of corrected N-SPT values, and finally the bearing capacity of a pile penetrating cohesion soil. By analyzing data from 40 boreholes located in 18 projects in Ho Chi Minh City, South VietNam, coefficients of determination between SPT numbers and physical and mechanical properties of different soil kinds are not the same: R2 = 0.623 for sand, =0.363 for sandy clay and =0.189 for clay. The spatial variability of soil properties is taken into account by calculating the scale of fluctuation θ=4.65m beside the statistically-based data in horizontal directions. Finally, the results from two theoretical approaches of predicting pile bearing capacity were compared to those of finite element program Plaxis 3D and static load test at site. Correlation between the capacity computed by using corrected N-values instead of soil strength and results of static load test has proved to be well suitable in evaluating the bearing capacity of driven and jack-in piles, particularly installing in the cohesive soil using the SPT blows.

Ambient and forced-vibration tests of the Beauharnois suspension bridge

2000 ◽  
Vol 27 (6) ◽  
pp. 1162-1172 ◽  
Author(s):  
P Paultre ◽  
J Proulx ◽  
T Bégin
Keyword(s):  
Forced Vibration ◽  
Dynamic Properties ◽  
Suspension Bridge ◽  
Rehabilitation Program ◽  
Mode Shapes ◽  
Experimental Program ◽  
Dynamic Amplification Factor ◽  
Dynamic Amplification ◽  
Vibration Tests ◽  
Steel Trusses

Ambient and forced vibration tests were carried out on the Beauharnois Bridge, a unique, 177-m combined suspension and cable-stayed structure near Montreal. A rehabilitation program was completed on the bridge during which the deck was completely rebuilt with an orthotropic slab on two steel trusses. The rehabilitation program also included the addition of two pairs of stay cables on both towers, creating a hybrid suspension system. The paper presents a series of dynamic tests performed to evaluate the dynamic properties and the dynamic amplification factor (DAF) for the rehabilitated bridge. The experimental program involved the measurement of vertical, transverse, and longitudinal acceleration responses of the deck and tower under ambient and controlled traffic loads. Displacement, strain, and integrated acceleration DAFs were computed under different loading conditions. Modal properties were evaluated and used to correlate a three-dimensional finite element model for the bridge, including nonlinear cable behaviour. The paper discusses the experimental setup and the techniques used to evaluate vibration frequencies, mode shapes, and the DAF. Correlation of numerical dynamic properties and experimental results is also presented. Key words: cable-stayed bridge, dynamic amplification, dynamic testing, numerical correlation, modal analysis, suspension bridge.

Geotechnical parameters of reclaimed sandfill from the cone penetration test

2005 ◽  
Vol 42 (1) ◽  
pp. 91-109 ◽  
Author(s):  
Yung-Mook Na ◽  
Victor Choa ◽  
Cee-Ing Teh ◽  
Ming-Fang Chang
Keyword(s):  
Stress Level ◽  
Cone Penetration Test ◽  
In Situ Stress ◽  
Load Test ◽  
Penetration Test ◽  
Cone Penetration ◽  
In Situ Tests ◽  
Geotechnical Parameters ◽  
Cone Resistance

Sandfill at reclaimed sites is usually formed by more than one placement method. Reclaimed sandfill is often highly variable, and the cone penetration test is most commonly used for site characterization. Correlations among the cone resistance and geotechnical parameters for sand are influenced by the in situ stress level, and it is important to incorporate the stress-level effect. In this study, cone penetration tests were performed at several levels from the top of a 10 m high surcharge, which was later removed step by step, and in situ density was determined layer by layer at the Changi East reclamation site in Singapore. Different ways of normalizing the cone resistance by the corresponding in situ stress were investigated. Specialized in situ tests including the self-boring pressuremeter test, the cone pressure meter test, the seismic cone penetration test, and the plate load test were conducted to provide the reference deformation characteristics of sandfill. Results of the in situ tests indicate that the sand density and the cone resistance profiles vary between areas formed by different sand placement methods. Site-specific correlations developed based on comparison of normalized cone resistance with the reference data obtained from laboratory tests and other in situ tests are found to be suitable for the evaluation of relevant soil parameters.Key words: stress normalization, cone resistance, correlations, geotechnical parameter, in situ characterization, granular soil.

Numerical Simulations of Vertical-Axis Wind Turbine Blades

2011 ◽  
Author(s):  
B. D. Plourde ◽  
J. P. Abraham ◽  
G. S. Mowry ◽  
W. J. Minkowycz
Keyword(s):  
Wind Tunnel ◽  
Numerical Simulations ◽  
Large Scale ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Test Facility ◽  
Wing Design ◽  
In Situ Tests ◽  
Initial Design

A recent research project has been focused on the design, manufacture, and testing of novel, vertical-axis turbines which can be directly attached to existing structures (such as communication towers) for local power generation, particularly in areas of the world where grid-connected electricity is unavailable. The proposed turbine has undergone a multitude of design stages, including the wing design, prototype fabrication, wind-tunnel testing, and manufacture. This report discusses the initial design process utilized to create the turbine wing. That process relied upon numerical simulations of the unsteady flow patterns which occur when the wing rotates. Results from the simulation were used to modify the wing design and significant improvements in performance were realized. Based on wind-tunnel tests, improvements on the order of 300% were obtained, compared to the initial design. Improvements of this magnitude have allowed the progression from prototype testing to large-scale manufacturing. The simulations allowed the implementation of novel design features such as preferentially deployed vents which allowed an increase of torque and a decrease of transverse loads. Results from the simulation were compared with experimental results obtained from a wind-tunnel test. In addition, data was extracted from an in situ test facility which was installed with wind-speed and data acquisition equipment. It was found that the results of the simulation were in close agreement with both the results from the wind tunnel and the in situ tests. The congruence gave added confidence to the veracity of the simulations.

scholarly journals Assessment of human-induced vibrations of a cable-stayed footbridge

2018 ◽  
Vol 211 ◽  
pp. 09001 ◽  
Author(s):  
Izabela Drygała ◽  
Joanna M. Dulinska ◽  
Marek Wazowski
Keyword(s):  
Natural Frequencies ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Fe Model ◽  
In Situ Tests ◽  
Modal Assurance Criterion ◽  
Comfort Criteria ◽  
Abaqus Software

The primary purpose of this research is the evaluation of human-induced vibrations of a cable-stayed footbridge. The cable-stayed pedestrian bridge with total length of the span equal to 46.90 m located in Czestochowa (Southern Poland) was chosen as a case study. The footbridge consists of two spans (21.10 m and 25.80 m). A three-dimensional (3D) finite element (FE) model of the footbridge was prepared with the ABAQUS software program. The dynamic properties of the structure, i.e. its natural frequencies, modes shapes and damping ratios, were estimated on the basis of the in situ tests results as well as numerical analysis. For the validation of the modal models the modal assurance criterion (MAC) theory was applied. In the next stage of the investigation the dynamic response of the structure to human-induced loading was evaluated. Finally, the vibration comfort criteria for the footbridge were checked.

Closure to “Dynamic Properties of Soils from In-Situ Tests”

1982 ◽  
Vol 108 (11) ◽  
pp. 1507-1508
Author(s):  
Shamsher Prakash ◽  
Vijay Kumar Puri
Keyword(s):  
Dynamic Properties ◽  
In Situ Tests
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