Value Of Vertical Displacement Research Articles

Numerical Simulation and Deformation Prediction of Deep Pit Based on PSO-BP Neural Network Inversion of Soil Parameters.

The finite element numerical simulation results of deep pit deformation are greatly influenced by soil layer parameters, which are crucial in determining the accuracy of deformation prediction results. This study employs the orthogonal experimental design to determine the combinations of various soil layer parameters in deep pits. Displacement values at specific measurement points were calculated using PLAXIS 3D under these varying parameter combinations to generate training samples. The nonlinear mapping ability of the Back Propagation (BP) neural network and Particle Swarm Optimization (PSO) were used for sample global optimization. Combining these with actual onsite measurements, we inversely calculate soil layer parameter values to update the input parameters for PLAXIS 3D. This allows us to conduct dynamic deformation prediction studies throughout the entire excavation process of deep pits. The results indicate that the use of the PSO-BP neural network for inverting soil layer parameters effectively enhances the convergence speed of the BP neural network model and avoids the issue of easily falling into local optimal solutions. The use of PLAXIS 3D to simulate the excavation process of the pit accurately reflects the dynamic changes in the displacement of the retaining structure, and the numerical simulation results show good agreement with the measured values. By updating the model parameters in real-time and calculating the pile displacement under different working conditions, the absolute errors between the measured and simulated values of pile top vertical displacement and pile body maximum horizontal displacement can be effectively reduced. This suggests that inverting soil layer parameters using measured values from working conditions is a feasible method for dynamically predicting the excavation process of the pit. The research results have some reference value for the selection of soil layer parameters in similar areas.

Regularities of the strain state of the embankment when varying the vertical element length of strengthening

The crisis that arose during the war in the transport system of Ukraine provided an opportunity to review the concept of integrating the Ukrainian railway into the European network. Corresponding changes, which require reconstruction of the railway, including track and embankment, have been analyzed. The railway embankment needs strengthening for its normal operation. The embankment reinforced with vertical elements, namely piles, has been studied. A finite-element model of the embankment, its soil base, and the rail-sleeper grid has been created. This model shows a vertical element of strengthening with lengths of 2.0, 4.0, and 6.0 m. The results of the numerical analysis are obtained, which makes it possible to analyze the values of horizontal and vertical displacements. The values of both components of the strain state are analyzed. The results of the analysis prove that strengthening with such elements has a maximally positive effect on both components of deformation. The regularities of changes in embankment displacements, when varying the vertical element length of strengthening, are linear. They prove that the presence of piles reduces the horizontal component by 1.1 … 1.32 times, and the vertical one by 1.1 … 1.24 times.

Analysis of the Surrounding Rock Full-Displacement Variation in Large-Span Mudstone Highway Tunnels

Analysis of the Surrounding Rock Full-Displacement Variation in Large-Span Mudstone Highway Tunnels

GROUND DEFORMATION MONITORING OF RECLAIMED LANDS ALONG MANILA BAY FREEPORT ZONE USING PS-INSAR TECHNIQUE

Abstract. In response to escalating land demands, land reclamation plays a vital role, but this comes with the challenge of ground deformations that threaten livelihoods and safety. To address the growing concern, Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) is utilized. This remote sensing method is known for its cost-effectiveness, efficiency, and high-resolution capabilities, to monitor vertical ground deformations in Manila Bay Freeport Zone's reclaimed areas. Through adaptation and implementation of PS-InSAR via SARPROZ, measurements along the satellite’s line-of-sight (LOS) is integrated both for ascending and descending geometries using the Nearest Neighbor Vector (NNV) approach to decompose and derive precise vertical displacement values. Correlation analysis with annual leveling data from six benchmarks reveals a strong relationship with correlation coefficient > 0.80. The results indicate relative stability with localized subsidence due to differential settlement and nearby construction. The results from the PS-InSAR technique show that ground deformation on reclaimed lands is expected to continue. Hence, monitoring should be implemented to observe sustained settlements after reclamation, identify areas with significant deformations, detect building and structural deformations, and initiate solutions to reduce the risk of environmental hazards.

Rapid Assessment of Landslide Dynamics by UAV-RTK Repeated Surveys Using Ground Targets: The Ca’ Lita Landslide (Northern Apennines, Italy)

The combined use of Uncrewed Aerial Vehicles (UAVs) with an integrated Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS) module and an external GNSS base station allows photogrammetric surveys with centimeter accuracy to be obtained without the use of ground control points. This greatly reduces acquisition and processing time, making it possible to perform rapid monitoring of landslides by installing permanent and clearly recognizable optical targets on the ground. In this contribution, we show the results obtained in the Ca’ Lita landslide (Northern Apennines, Italy) by performing multi-temporal RTK-aided UAV surveys. The landslide is a large-scale roto-translational rockslide evolving downslope into an earthslide–earthflow. The test area extends 60 × 103 m2 in the upper track zone, which has recently experienced two major reactivations in May 2022 and March 2023. A catastrophic event took place in May 2023, but it goes beyond the purpose of the present study. A total of eight UAV surveys were carried out from October 2020 to March 2023. A total of eight targets were installed transversally to the movement direction. The results, in the active portion of the landslide, show that between October 2020 and March 2023, the planimetric displacement of targets ranged from 0.09 m (in the lateral zone) to 71.61 m (in the central zone). The vertical displacement values ranged from −2.05 to 5.94 m, respectively. The estimated positioning errors are 0.01 (planimetric) and 0.03 m (vertical). The validation, performed by using data from a permanent GNSS receiver, shows maximum differences of 0.18 m (planimetric) and 0.21 m (vertical). These results, together with the rapidity of image acquisition and data processing, highlight the advantages of using this rapid method to follow the evolution of relatively rapid landslides such as the Ca’ Lita landslide.

Biomechanical evaluation of screw and cement placement strategies for treating medial uncontained tibial defects in total knee arthroplasty: A finite element analysis.

Total knee arthroplasty faces challenges in the management of medial uncontained tibial defects, affecting prosthesis stability and implant survival. The use of screws and bone cement is a preferred approach; however, optimal screw insertion techniques lack consensus in the existing literature. The present study aimed to address this gap by exploring optimal screw and cement placement strategies, focusing on their biomechanical implications. The present study conducted a finite element analysis using a knee prosthesis model with a defined uncontained tibial defect. Various parameters were systematically adjusted, including the number of screws (1, 2 or 3 screws), screw lengths (10, 18, 30 or 40 mm), lateral-medial screw positions (2, 4 or 6 mm laterally) and abduction rotation angles (0, 5, 10 or 15 degrees). These adjustments were made to evaluate their specific and combined impacts on the vertical displacement and abduction angles of the tibial tray. The results revealed that incorporating three-screw reinforcement markedly reduced vertical displacement, while the single screw in the middle position exhibited superior performance in preventing the deformation of abduction angles compared to scenarios with two screws at anterior and posterior positions without a middle screw. Longer screws and smaller abduction angles contributed to decreased movement of the tibial component. Furthermore, the lateral adjustment of the screw position led to an increase in vertical displacement values, reaching ~1.5% when shifted 6 mm laterally. On the whole, the finite element analysis in the present study suggests that, for the treatment of medial uncontained tibial defects, three-screw reinforcement is advantageous for larger defects. Longer screws and a smaller abduction angle are deemed favorable. Moreover, the results underscore the superiority of medial screw placement over lateral placement. It is imperative to note that further clinical validation is essential to corroborate the biomechanical implications observed herein.

Shearing behavior of suction caisson wall-sand interface throughout the suction caisson life-cycle

Suction caissons are widely used as foundations for offshore platforms and offshore wind turbines. The life-cycle of a suction caisson includes penetration, service and retrieval. The mechanical characteristics of the interface between sand and suction caisson wall are crucial for assessing the penetration behavior and bearing capacity of suction caissons. Interfacial shear tests under constant normal loading (CNL) and variable normal loading (VNL) conditions were conducted to investigate the shearing behavior of suction caisson wall-sand interface throughout the suction caisson life-cycle. Results show that the interfacial shear stress increases with an increase in normal stress and decreases with an increase in penetration rate throughout the life-cycle of the suction caisson. The value of vertical displacement of the interface decreases with an increase of cycle times during service and the sand particles’ movement, rotation and rolling were observed by visualization tests. Under the test conditions, the interface frictional coefficient ranges from 0.46 to 0.80 and the interface friction angle varies between 25.64° and 27.43° during retrieval. Both the interface friction angle and interface friction coefficient during the penetration stage are greater than those during the retrieval stage, indicating that retrieval stage is not an inverse process of penetration stage. In addition, the control groups were carried out to investigate the effect of penetration on service stage and the effect of service on retrieval stage. It was also found that the influence of the penetration stage on shear stress during service stage is mainly observed in the first two cycles. The influence of service stages on shear stress during retrieval stage is more obvious. After prolonged cycling during service stage, the strength of the interface would be reduced.

Finite element analysis and retrofit of the existing reinforced concrete columns in Iraqi schools by using CFRP as confining technique

Abstract There are many studies about the use of carbon fiber-reinforced polymer (CFRP) to strengthen concrete members such as columns, beams, and slabs. The effectiveness of these strengthening techniques has been proved by enhancing the mechanical properties of concrete structures. So, CFRP has been used to strengthen and repair existing concrete structures in Iraq. For example, in Al-Mosul city, the strengthening and repairing system is done for concrete members such as beams, columns, and slabs using the Near Surface Mounted or confinement technique. Therefore, the research aim is to use CFRP for maintenance as an alternative material to strengthen and repair concrete members in Iraqi schools. This article employs methods to enhance and repairing of some of concrete columns at Al-Abeer school in Najaf city by using modern materials as an alternative method of maintenance. In addition, finite element analysis was carried out using Abaqus software to verify the effectiveness of strengthening. The reinforced concrete (RC) column strengthened by using fiber-reinforced polymer as a confining technique increased compressive strength by about 91% compared to the control column. In addition, the value of strains increased to nearly 100% in the longitudinal direction with the stability of the value of the lateral strains, despite the occurrence of a significant increase in the compressive strength capacity. So, the values of vertical displacement at stress 4 MPa were 22.3 mm for the strengthened RC column and 5 mm for the control RC column. Thus, the strengthened RC column increases the values of compressive strength with a decrease in displacement to approximately 22%. Four years ago, the strength of the school building was assessed, thus the success of the strengthening.

Dynamic Response of Layered Media to Impact Loading (on the Example of Highways)

Introduction. The main way to assess the load-bearing capacity of road structures (which are layered media consisting of materials of different stiffness) is through impact testing. The analysis of the results of these tests is reduced to the consideration of only peak values of vertical displacements without taking into account the change of these parameters in the frequency and time range. At the same time, it is the study of amplitude-frequency characteristics of displacements that can allow solving a number of urgent problems related, for example, to bringing the actual values of vertical displacements to the values under the design modes of operation of the structure.The purpose of the study is to analyze the dynamic response of layered media (road structures) of automobile roads to impact loading, aimed at bringing the actual parameters of the dynamic response to the design values regulated by the requirements of domestic regulatory documents on road design.Materials and Methods. Modern shock loading facilities allow to reproduce the load with a pulse time of 0.03 s, while the design values of elastic moduli are calculated for 0.1 s. To overcome this contradiction, the authors realized an exact solution of the dynamic Lame equation for a multilayered half-space and constructed a series of amplitude-frequency characteristics of displacements, from the processing of which a simplified functional dependence was derived.Results. The methodology of construction of amplitude-frequency characteristics of displacements on the surface of road pavement under impact impact has been developed, which finds its practical application. On the basis of the exact solution of the dynamic Lame equation by means of statistical processing, a simplified regression dependence for vertical displacements is established. An example of calculation of the elastic moduli of the road structure layers taking into account their reduction depending on the time of load application is presented.Discussion and Conclusion. Within the framework of the study, for the first time, a methodology for bringing the actual values of vertical displacements to the values under the design modes of operation of a road structure, based entirely on the computational analysis of its dynamic VAT, in particular, the amplitude-frequency characteristic of deformation under unsteady impact, has been obtained. The developed approach is able to significantly increase the reliability of diagnostics of highway condition, as well as to ensure the unity of measurements and results obtained during the design and diagnostics of roads.

Analytical Study Of Load Rating On RCC Box Girder Superstructure Under The Effect Of IRC Loadings

It is observed that over the course of time structural components weakens and their ability to carry the self weight along with the superimposed load decreases. Consequently, it becomes very much important and vital to periodically assess the strength, stability and the performance of the bridge and other structure in order to ascertain their remaining residual strength and to ensure safety. There are different experimental methods available which uses the concept of Non-Destructive testing in order to ascertain the performance and the condition of any structure at any point of time. There are numerous experimental method which are used to perform the Load Rating Analysis but there is no provision to perform the same rating analysis analytically as per the Indian code on bridge related software. This paper generally deals with providing an analytical solution which can be used in order to estimate the residual strength of the bridge structure and perform the Load Rating Analysis analytically on Midas Civil Software. The study basically involves the modelling and Analysis of 2 Reinforced Concrete Box Girder Superstructure, each of span length 40m situated in Lucknow analyzed as per the Indian Standard Codes. Both of the bridge model represents the condition of the bridge structure at a specific time period. The time gap between the analysis of the two models is assumed to be 70 years. The bridge model is modelled and analyzed with the help of Midas Civil Software and the Load carrying capacity of the structure is evaluated based on the different statistical parameters such as Vertical Displacement, Shear Force and Bending Moment. At last a comparative study is conducted between the two models. The analysis revealed that the Bridges Lose their load bearing capacity and strength after a time period of 70 years. A considerable increase in the value of vertical displacement and bending moment was observed beyond the safe and permissible limit of the structure. The analytical approach demonstrated in this study can be applied to various bridge structure such as RCC and PSC Tee Beam Bridge, I Girder bridge, cable stayed bridge etc.

Numerical Simulation of Severe Damage to a Historical Masonry Building by Soil Settlement

Historical masonry structures, which constitute an important part of the historical heritage, exhibit brittle behavior under tensile stresses due to earthquakes or soil movements/settlements. Therefore, they are sensitive to deformation. The soil–structure interaction problems play an important role in the damage to historical masonry structures. Different settlements, slips, and deformations in foundations causes damage to, and/or partial collapse the load-bearing walls. This study provides a numerical simulation of a historic masonry building on the north coast of Turkey, dating from 19th century, which suffered severe damage due to soil settlement by excavation activity near the building. FE models of the building with and without the soil–structure system were created to identify the damage to the building following soil settlement. The height of the soil domain (bounded as a fixed boundary condition) was accepted in the range of 1.5 m to 15 m. The damage propagation between the numerically obtained damage and the existing damage to the building was detailed and compared. In terms of displacement, the maximum vertical and horizontal displacement values reflecting the existing damage to the building were determined as 22 mm and 85 mm, respectively. The soil depth of 6 m was also considered acceptable for deciding the soil–structure interaction. For this, the sum of the rigid basement and the soil depth can be selected to be equal to the total height of the building participating in free vibration. It was concluded that the numerical procedure employed provided an effective representation of existing damage to a building due to soil settlement. Moreover, the procedure described can be adopted for possible collapse simulation.

Introducing waste glass powder as a sustainable constituent in microsurfacing

This study examines the merits of using waste glass powder (WGP) in a microsurfacing mixture as a replacement for mineral filler. The replacement was done at 0%, 25%, 50%, 75%, and 100% by weight of the mineral filler. The performance of WGP-modified microsurfacing mixtures was evaluated through mix time test, wet cohesion test, wet track abrasion test, loaded wheel test-sand adhesion and loaded wheel test-horizontal and vertical displacement. The toxicity, chemical, and microstructural characteristics were respectively assessed using a toxicity characteristic leaching procedure, Fourier-transform infrared spectroscopy and field emission scanning electron microscopy. Performance analysis of the mixtures showed that an increase in WGP significantly enhanced the mixture's resistance against stripping, bleeding and rutting. The aggregate loss, sand adhesion, horizontal displacement and vertical displacement values at a WGP content of 75% were approximately 62%, 20%, 30% and 36% lower than the values of these parameters at a WGP content of 0%, respectively. Toxicity characteristic leaching tests were performed to compare the extent of heavy metals leaching from stockpiled WGP and from WGP-modified microsurfacing mixtures. It was found that heavy metals leaching from WGP-modified mixtures were 80% lower than heavy metals leaching from stockpiled WGP. The significant reduction in leachate could be attributed to the bitumen covering WGP and preventing WGP particles from exposure to water, as evidenced by microstructural analysis.

Dynamic Response Analysis of Airport Pavement under Impact Loading

The safety of the airport runway, as an infrastructure, is of considerable concern. The existing research has problems of hysteresis and unreasonable load application. In this paper, ANSYS is used to construct a coupled tire–pavement model to study the dynamic characteristics of airport asphalt pavements under impact loading. Taking the Boeing 737–800 as an example, the impact of an aircraft landing on an airport pavement is simulated by applying a dynamic load to the landing gear. The effects of tire pressure, landing pitch angle, and sinking speed on the dynamic response of the airport runway are investigated. The effects of each factor of the airport pavement are analyzed by comparing the maximum effective stress, effective strain, and displacement in the vertical direction at the same position of different structures. The results show that when the tire pressure is 2.0 MPa, the maximum values of effective stress, effective strain, and vertical displacement increase by 29.8%, 19.1%, and 22.2%, respectively, compared with 1.0 MPa. The maximum values of effective stress, effective strain, and vertical displacement at the 3.0 m/s sinking speed increase by 25.2%, 93.1%, and 77.1%, respectively, compared with that at the sinking speed of 1 m/s, which indicates that the effect of sinking speed on the dynamic response of the pavement is more significant. However, the change in the landing pitch angle has little impact on the response parameters of the pavement. Meanwhile, the flexural tensile stress at the bottom of the surface and the equivalent effect at the top of the soil foundation must be considered in the design of the airport pavement structure.

Экспериментальное исследование деформированного состояния металлоконструкций грузовых тележек кранов мостового типа с универсальной компоновочной схемой

Deformations of the supporting metal structures of machines for various purposes have a significant impact on the performance of the equipment installed on them. Insufficient rigidity of a metal structure can cause jamming and failure of drive elements and working bodies of material handling, construction and road machines, the operation of which is associated with the impact of high static and dynamic loads. Therefore, when designing new structural schemes of load-bearing metal structures, special attention must be paid to the issue of ensuring the necessary rigidity. The presented work contains the results of an experimental assessment of the deformed state of physical models of the metal structures of load trolleys of overhead cranes, made on the basis of a multipurpose layout drawing using various types of connections of bearing elements. The article reflects information about the methodology of experimental research, describes the features of the physical models of metal structures used in the course of the experiment. The data on the vertical displacements of the control points of metal structures when using various loading schemes are given. An assessment was made of the influence of the type of applied connections of load-bearing elements on the features of the resulting deformed state of the metal structure. A comparative analysis of experimental data and calculated values of vertical displacements of points of metal structures obtained as a result of computer simulation of the formed state using various finite element models is performed.

Analysis of displacement evolution characteristics of reverse-dip layered rock slope based on geological geometric partition

To investigate the toppling displacement evolution characteristics of anti-dip rock slopes, the Xiaodongcao-Zhengjiadagou bank slope is taken as an engineering case, and firstly, the geological geometric distribution characteristics of the slope are obtained by superimposing the lithology, slope, and elevation raster layers of the slope through ArcGIS, and the geological partition with the largest area is the Lower Triassic Daye Formation, bottom elevation, and medium slope; based on the actual surface displacement monitoring data, the spatio-temporal evolution nephogram of toppling displacement of bank slope every half year is interpolated by Inverse Distance Weight method, and then the last displacement nephogram is assigned to the thousandth and superimposed with the geological geometric partition to obtain the displacement superposition characteristics. The results show that: the obvious zone of horizontal displacement deformation mainly occurs in the front and middle of the bank slope, mainly shear deformation, vertical displacement is primarily in the front and the back edge of the bank slope and the total displacement deformation is more similar to the horizontal displacement; the horizontal displacement value is larger than the vertical displacement value, the horizontal displacement deformation controls the overall deformation of the bank slope; through the analysis of the geometric superposition evolution of the anti-dip rock slope, the displacement superposition strong deformation zone is located at the boundary between the Triassic Jialingjiang Formation (T1j) and the Triassic Daye Formation (T1d).

Predicting underground mining impact on the earth’s surface

Purpose. Development of a digital model of the stress-strain state of a rock mass during the extraction of coal by an underground method to predict the displacement of the earth’s surface. Methodology. The proposed technique is based on modeling the stress-strain state of a rock mass using the finite element method. Computer simulation of the stress-strain state of the rock massif was carried out in the area of lavas worked out in previous years in layers with the index K of the Karaganda suite of the mine named after Kostenko of the Karaganda coal basin, where instrumental surveying measurements were previously made to monitor the vectors and numerical values of the displacements of the earth’s surface undermined by mining. Findings. The reliability of the obtained finite element model of a rock mass for predicting the process of displacement of rocks and the earth’s surface is confirmed by the results of full-scale instrumental mine surveying measurements on the earth’s surface. Originality. For the first time, a method has been proposed for predicting the shifts of points on the earth’s surface, taking into account the physical and mechanical properties of rocks, based on a finite element model of a rock mass. A new approach was applied to assess the reliability of the model of the stress-strain state of a rock mass based on a comparison of the results obtained with the data of instrumental mine surveying. Practical value. A technique for computer simulation of the stress-strain state of a rock mass during the extraction of hard coal at the mine named after Kostenko, owned by one of the world’s leading steel producers, JSC ArcelorMittal. For modeling, a site was chosen in the area of lava mining along the coal seams of the Karaganda Formation of seams, starting from the K18 seam to the K10 seam, that is, a rock mass with a depth of more than 700 m. Previously, within this area a series of instrumental surveying observations was carried out of the displacement of the earth’s surface during the working out of these lavas using the method of roof management – complete collapse. The obtained values of vertical displacements of a point on the earth’s surface according to the results of computer simulation of the stress-strain state of a rock mass correspond to the data of field mine surveying observations of displacements of the same point, which confirms the reliability of the constructed model.

An Efficient Methodology for Detecting the Vertical Movement of Structures

Details regarding the public safety of engineering structures can be gleaned from measurements and monitoring. The development of a methodology for monitoring and analyzing structures' vertical displacement is explained in this paper. The developed methodology aims to add a new dimension to geometric leveling, and leveling routing, by applying a least squares solution for level network adjustment and performing statistical analysis to assess the change in vertical displacement. To monitor and analyze the vertical deformation of a building in Cairo, Egypt, the proposed methodology was utilized. Twenty monitoring points, five auxiliary points, and three local reference stations were utilized. All the measurements were taken with a geodetic invar staff and an automatic level with an attachment of a parallel plate micrometer. The observations were made for an interval of 81 months. The least squares adjustment technique was applied to obtain the adjusted levels and observations and to generate the required statistical data. The results of the subsequent epochs were compared to the results of the first epoch to determine the vertical movement of the monitoring points for each epoch. In addition, the significance of the present displacement was ascertained by comparing the values of vertical displacement to the determined 95% corresponding confidence intervals. The findings demonstrated that the building remained stable throughout the monitoring period. The case study demonstrates how effectively geometric leveling with least square adjustment can be used to monitor the vertical displacement of structures.

Influence of Underground Excavation Expansion on Surrounding Rock Characteristics at Intersection of Ventilation Shaft and Tunnel: A Case Study

Existing railways can no longer meet transportation requirements, and it is an urgent need to expand old tunnels. However, the existence of ventilations shaft makes expansions face greater risks. This study analyzed the tangential stress change trend during the expansion process through field monitoring, and numerical simulation was used to analyze the changes in stress and displacement under different shaft depths and width–span ratios. The results show that as one approaches the tunnel face, the tangential stress in the arch foot and side wall of the J-2 and J-3 sections gradually increased, and the tangential stress in the arch foot and side wall of the J-1 section gradually decreased. The distance of the tunnel expansion’s influence on tangential stress is about 0.91 to 1.45 times the tunnel span. The largest value of vertical displacement had a linear relationship with shaft depth, and the largest value of horizontal displacement had a quadratic relationship with shaft depth. Changes in the width–span ratio only had a greater impact on the ventilation shaft section. These results can provide a reference for similar in situ expansion projects.

Structural Performance Comparison of Structural Systems Using LIRA and ETABS

This paper investigates a comparison of structural systems of high rise (96m of 30 stories) buildings subjected to gravity load and wind load of speed 90mph. Three structural systems, Moment frame system, Shear wall system, and Tube-in-Tube system of identical base area and loadings are structurally designed, in ETABS and LIRA software. Linear wind response analysis was carried out as per ASCE 7-05. Parameters like fundamental time period, Maximum story displacement, Maximum column axial load and Vertical floor displacement are considered in this study. As per the findings, the maximum story displacement is found to be within the allowable limiting value. Tube-in-Tube system shows a better performance from the other systems for minimizing the story displacement. The modal time period, vertical displacement and Maximum column axial load values are also minimum in Tube -in-tube system.

Comparative in vitro study on biomechanical behavior of zirconia and polyetheretherketone biomaterials exposed to experimental loading conditions in a prototypal simulator

Zirconia and polyetheretherketone (PEEK) are two biomaterials widely investigated as substitute for metals in oral prosthetic rehabilitation. To achieve a proper biomechanical behavior, the prosthetic biomaterials must ensure a good resistance to loads, as this is a crucial characteristic enabling their use in dental applications. The aim of this study was to investigate differences in the fracture resistance of different biomaterials in an experimental environment: fixed partial dentures (FPDs) screwed in a prototype of biomimetic mandible. 10 Samples of FPDs were allocated in 2 groups (A and B): Group A (n=5) involved FPDs in zirconia-ceramic, and Group B (n=5) involved FPDs in PEEK-composite. The samples were loaded by means of a three-point bending mechanical test, and the load to fracture has been evaluated generating a point-by-point graphics (speed/load and time/deformation). The samples were further analyzed by micro-computed tomography (micro-CT) and described under experimental loading conditions. Zirconia-ceramic FDPs were the samples reporting the worst results, showing a lower value of vertical displacement with respect to PEEK-based samples. The micro-CT results have further confirmed the preliminary results previously described. This in vitro study aims to give analytic data on the reliability of PEEK as a reliable and strong biomaterial for prosthetic treatments.