Vertical Displacement Changes Research Articles

Geometric nonlinear stiffness and frequency of the traditional spring-suspended free-vibration testing device

Free vibration tests on bridge deck sectional models in wind tunnels have been widely adopted to study the wind-resistant performances of bridges. The traditional spring-suspended free-vibration testing device is suitable for small torsional amplitude vibration tests. When large torsional displacement occurs, a geometry nonlinear will be introduced, and the stiffness and frequency of the traditional device will change. However, quantitative research on this subject is inadequate at present. Based on proper simplifications and assumptions, new analytical formulas are derived that describe how the torsional and vertical stiffnesses of the traditional device vary as the torsional and vertical displacement change for different spring lengths, initial strains, joint spacings, and stiffnesses. The amplitude-dependent torsional frequency is also quantified based on the potential energy function. It is found that the torsional stiffness reduction rate Rα and frequency reduction rate RfAα nonlinearly increase with the torsional displacement α and amplitude Aα, respectively. In the parameter ranges considered, R10° is basically within 4%–6%, R20° is basically within 15%–28%; Rf10° is basically within 1%–2%, Rf20° is basically within 6%–11%. From the view of geometry nonlinear, the maximum torsional amplitude of the traditional device is suggested to be less than 4°. Although Rα can be effectively reduced by increasing the initial strain and length of the upper and lower springs, it cannot be completely eliminated whatever increasing the above parameters. The vertical stiffness reduction rate can be ignored.

Reversed tension characteristics in subsea mooring connectors for an FPSO SPM in shallow water

The reversed tension on subsea mooring connectors is studied to prove its appearance. The mooring line is chosen from the real single point mooring system of Floating Production Storage and Offloading Unit (FPSO) wording in the South China Sea. The forced motion excitations are applied on the top end of the mooring line with the data monitored by the GPS device on the FPSO. The simulations are carried out with the lumped mass model and the nonlinear finite element model to verify the accuracy of the whole process. In the results of the forced excitation case, the reversed tensions are found three times. The occurrence of the revered tensions is consistent with the minus peak of the vertical displacement in time history, and the vertical displacement is recognized as the key factor for the reason of reversed tension. The reversed tension will apply a compression force on the rigid subsea mooring connect after a generous vertical displacement change. It may lead to the failure of the connector, and then the mooring line. Therefore, the minimum tension design is suggested to be added to the rules of classification society to avoid the reversed tension and slack condition of the mooring line.

Dynamic Analysis and Seat Selection of Bus Driving Comfort under Different Road Conditions

The comfort of a bus running on different road conditions is a matter of public concern. In this paper, the differential equations of motion are established for a bus running on different road conditions and the whole driving process is mechanically analyzed. Firstly, the bump degree at different positions is quantitatively analyzed and it is found that the rear row is bumpier on different roads. Then, the relationship between the speed of the bus and the vertical displacement and acceleration is quantitatively described. Regardless of the speed, a similar displacement and acceleration will be eventually achieved, but the speed is higher, and the duration of maximum displacement and acceleration is longer. When the speed is 8 m/s, resonance occurs on the bus during road condition II. Finally, the change in vertical displacement and acceleration under the action of different spring stiffness coefficient ratios of the front and rear wheels is quantitatively analyzed. High stiffness ratios mean less displacement and acceleration. By establishing an actual excitation road surface, the differential equations and analytical solutions in this paper can be used to roughly analyze the mechanical response of a traveling bus. These results can provide some guidance for the design and driving of buses.

Effect of Oblique SV Wave on the Seismic Response of Mountain Tunnel

In order to study the dynamic response of parallel mountain tunnels under the oblique incidence of seismic waves, based on the display finite element method and using viscoelastic artificial boundary, the oblique incidence of three-way seismic waves was realized by angular incident mode. The displacement and stress distribution characteristics of the tunnel lining under different propagation angles and vibration angles of SV waves were studied. The results show that the oblique incidence of SV wave has a certain effect on the displacement of the double tunnel, the forces in the tunnel are symmetrical and the axis displacement increases with the increase of incident angle, and the vertical displacement changes greatly. The stress of the tunnel lining under the oblique incidence of the SV wave is elliptical. The peak value of the maximum principal stress appears at the maximum span on both sides, and the maximum principal stress decreases with the increase of the vibration angle. The maximum principal stress of the right tunnel is flat. The minimum principal stress of the left and right holes decreases with the increase of vibration angle, and the minimum principal stress of the left hole is 90°∼270°. The distribution of the minimum principal stress in the range is large. Mises stress increases with the increase of the incidence angle of seismic waves.

Effect change of extra-wide concrete self-anchored suspension bridge under blast loads and its prediction considering time-dependent effect

In order to study the dynamic response of self-anchored suspension bridge with extra-wide concrete girder under explosive load, a real bridge was taken as the background, which is the widest on in China at present. Firstly, the refined finite element model (FEM) of the whole bridge was established. The reliability of numerical simulation method was validated by the measured data of the bridge at completion state and explosive test results of scaled girder specimen. The vertical displacement, reinforcement strain, acceleration and failure characteristics of the girder specimen under the explosive load of 3 kg TNT were analyzed. Through parametric simulation, the effects of different scale distance, concrete strength and reinforcement ratio on the explosion response of girder specimen were studied. Secondly, the dynamic responses of girder were studied. Finally, the change law of dynamic response at different ages was analyzed. The results show that the elliptical crack is formed on girder top plate. The maximum girder vertical displacement reaches 135.9 mm under 1000 kg, and the maximum increasing ratio of hanger force is 27%. The influence brought by the extra width of girder is significant. The girder vertical displacement changes along transverse direction and the concrete breach sizes are different. In addition, with the increase of service age, the girder displacement increases from 60.50 mm to 106.16 mm under the same explosive load. The research results can provide an important basis for the anti-explosion protection and reinforcement of similar extra-wide concrete self-anchored suspension bridge.

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.

Numerical simulation analysis for the effect of water content on the intelligent compaction quality of roadbed

<abstract> <p>In the process of intelligent compaction of roadbeds, the water content of the roadbed is one of the important influencing factors of compaction quality. In order to analyze the effect of water content on the compaction quality of roadbeds, this paper is developed by secondary development of Abaqus finite element numerical simulation software. At the same time, the artificial viscous boundary was set to eliminate the influence of boundary conditions on the results in the finite element modeling process, so that the numerical simulation can be refined to model. On this basis, the dynamic response analysis of the roadbed compaction process is performed on the finite element numerical simulation results. This paper established the correlation between compaction degree and intelligent compaction index CMV (Compaction Meter Value) and then analyzed the effect of water content on the compaction quality for the roadbed. The results of this paper show that the amplitude of the vertical acceleration is almost independent of the moisture content, and the vertical displacement mainly occurs in the static compaction stage. The vertical displacement changes sharply in the first 0.5 s when the vibrating wheel is in contact with the roadbed. The main stage of roadbed compaction quality increase is before the end of the first compaction. At the end of the first compaction, the roadbed compaction degree increased rapidly from 80% to 91.68%, 95.34% and 97.41%, respectively. With the increase in water content, the CMV gradually increased. At the end of the second compaction, CMV increased slightly compared with that at the end of the first compaction and stabilized at the end of the second compaction. The water content of the roadbed should be considered to be set slightly higher than the optimal water content of the roadbed by about 1% during the construction of the roadbed within the assumptions of this paper.</p> </abstract>

Biomechanical comparison of tuberosity-based proximal humeral locking plate compared to standard proximal humeral locking plate in varus cantilever bending

PurposeIn a prior biomechanical study using a tuberosity-based proximal humeral locking plate (TBP) an improvement in greater tuberosity (GT) fixation strength with the TBP compared to a standard proximal humeral locking plate (PHLP) was demonstrated. The purpose of this study is to compare the TBP to the PHLP with a simulated calcar gap fracture under cyclic varus cantilever forces. MethodsSeven matched pairs of cadaveric humeri were studied and 11A2.3 proximal humerus fractures were created by a 1 cm gap osteotomy at the surgical neck. Matched pairs were randomized for fixation using either a PHLP or a TBP. The proximal articular aspect of the humerus was potted and secured to the base of a load frame. The shaft was subjected to cyclic varus cantilever loading with a roller positioned 8 cm from the osteotomy. Change in vertical displacement of the diaphyseal fragment was monitored and digital images were obtained. Failure was defined as vertical displacement greater than 20 mm. Specimens not exhibiting failure over the course of 10,000 cycles were then loaded to 20 mm of vertical displacement. Reactant forces of the specimens at these displacements were recorded. ResultsFour/seven TBP specimens and four/seven PHLP specimens survived 10,000 cycles. The average cycles to failure for TBP specimens was 7325 cycles and 5715 cycles for PHLP specimens (p = 0.525). For the specimens that survived 10,000 cycles, the decrease in calcar gap was superior in the TBP specimens (p = 0.018). A similar trend was seen when these specimens were loaded to failure where the percent calcar gap recovery was higher for the TBP at 74.71 ± 10.07% versus 53.22 ± 30.35% for the PHLP (p = 0.072). In specimens that were loaded to failure after survival of 10,000 cycles the average stiffness of the TBP construct was 20.51 N/mm, and 11.74 N/mm for the PHLP construct (p = 0.024). ConclusionIn addition to superior GT fixation shown in a prior study, the TBP construct demonstrates significantly greater stiffness at the neck fracture compared to the PHLP, when loaded to failure. In addition, there was a trend towards less collapse in this calcar gap model.

Dynamic response of pre-disintegrated carbonaceous mudstone embankment under multi-lane vehicle load.

The purpose of this study is to reveal the response of multi Lane pre disintegrated carbonaceous mudstone embankment under vehicle dynamic load. In this paper, the pre-disintegrated carbonaceous mudstone samples whose fractal dimension meets the requirements are obtained through the indoor disintegration test of carbonaceous mudstone. Geotechnical basic tests such as particle analysis experiments, compaction tests, and direct shear tests were carried out on the pre-disintegrated carbonaceous mudstone samples, and the physical and mechanical parameters of the pre-disintegrated carbonaceous mudstone were obtained. On this basis, a two-way 4-lane pre-disintegration carbonaceous mudstone embankment model of the expressway was established by ABAQUS numerical software. Three different working conditions are set up to study the dynamic response of multi-lane pre-disintegrated carbonaceous mudstone embankment under vehicle load. The results show that the stress change trend on the surface of the pre-disintegrated carbonaceous mudstone embankment without vehicles is the same as that on the side with vehicles. Under this condition, the vertical displacement of the pre-disintegrated carbonaceous mudstone embankment surface can be as high as 4.33mm, and the vertical displacement change of the embankment in the 0–0.6s phase is basically the same as the stress amplitude distribution. When a traffic jam occurs on one side, the maximum increase in vertical stress on the surface of the embankment on the normal driving side is about 170 kPa compared to condition one, and the vertical displacement at each depth of the embankment has been significantly increased. When a traffic jam occurs on one side, it can significantly increase the vertical stress on the surface of the pre-disintegrated carbonaceous mudstone embankment in this lane. The middle part of the stress time curve of monitoring points 3 and 4 in working condition three is more stable and significant than in working condition one, and the maximum vertical displacement is increased by about 1.70mm. The research results can reference the stability analysis of carbonaceous mudstone embankments and engineering practice.

Analysis of the Effect of the Friction Coefficient on a Pavement Structure

Insufficient skid resistance of pavement is one of the main causes of traffic accidents. In this study, the influence of the friction coefficient on the internal effect of the pavement structure is studied deeply by establishing the asymmetric finite element numerical model. The model analyzes the inner stress, strain, and displacement variations of the pavement, with friction coefficients under the conditions of 0.3, 0.5, 0.8, and 1.0 and the action of the nonlinear superposition between the single-point static vertical load and horizontal load. In addition, against the limitations of the scatter calculation results, this paper analyzes the distribution of the internal stress field and displacement field. The results show that, with the attenuation of the friction coefficient, the distribution law of stress, strain, and displacement on the road surface (Z = 0) remains unchanged, and the maximum principal strain and the third principal strain on the Z-axis decrease monotonically with increasing depth. With the attenuation of the friction coefficient, the horizontal displacement inside the pavement structure gradually decreases, the vertical displacement changes insignificantly, and the principal stress gradually decreases. The principal strain and maximum shear stress inside the pavement structure show different changing rules.

Simulation Analysis of Cavity Shape of Compound Pendulum Jaw Crusher

Taking the working device of PE1500 × 1800compound pendulum jaw crusher as the research object, 3D model of working devices of four different cavity shape compound pendulum jaw crushers is carried out by using SolidWorks, and then the kinematic simulation software ADAMS is imported to carry out the kinematic simulation, and the horizontal and vertical displacement change curves of four characteristic points of the lower part of the crushing cavity are obtained. According to the simulation results, the relative production capacity and the block-up coefficient of each broken layer of the jaw crusher are calculated under the same spindle speed and different cavity shape. The results show that the block-up coefficient of the crusher with curved crushing chamber is smaller and its relative production capacity is larger.

Control Effect Analysis of a Bridge under Control of Neutral Equilibrium Mechanisms (NEMs) as Multiple Virtual Piers

When natural disasters occur, real-time disaster relief operations need to be implemented. But if disaster relief transportation is interrupted, these operations will be severely hampered. Emergency relief bridges must be erected so that people, materials and machinery can reach the disaster area smoothly. Therefore, one indispensable tool of disaster relief organizations is the light bridge. The design of such a lightweight bridge is controlled by deformation, not strength, so the span of the bridge is limited. Thus, this study proposes a bridge with multiple NEMs acting as multiple virtual piers of the bridge and an active structural control method was adopted to expand the span of the light bridge. The experimental results showed that, for the maximum vertical displacements at 1/3 and 2/3 distances from the left side of the bridge under uncontrolled and controlled conditions, the displacement reduction rates of the bridge were 96.20% and 98.42% for the outbound trip and 93.32% and 98.47% for the return trip, respectively. For the displacement control at the midpoint of the bridge under uncontrolled and controlled conditions, the displacement reduction rates of the outbound and return trips were 96.77% and 96.62%, respectively. The images from the experiment also showed that the cantilever arm of each NEM could be rotated by the PID controller to the appropriate angle to provide sufficient upward force to balance the vertical displacement changes based on the position of the moving load. Thus, zero-displacement control of a bridge can be achieved, and the control effect is quite significant.

Determining dislocation love number of vertical displacement using GPS observations: case study of 2011 Tohoku-Oki earthquake (Mw 9.0)

SUMMARYThe concept of determining the dislocation Love numbers using GNSS (Global Navigation Satellite System) data and calculating the corresponding Green's functions is presented in this paper. As a case study, we derive the dislocation Love number h of vertical displacement by combining 1232 onshore GPS data and 7 GPS-Acoustic data with the 2011 Tohoku-Oki earthquake (Mw 9.0). Three fault-slip distributions are used to compare and verify the theory and results. As the GPS stations are only located in Japan Island and along the Japan trench, we use the theoretical vertical displacements of a spherically layered Earth structure to constrain the low-order signal. The L-curve and an a priori preliminary reference skill are applied in the inversion method. Then, the GPS-observed vertical displacement changes are used to invert for the vertical displacement dislocation Love numbers h based on three different fault-slip models. Our results indicate that the estimated dislocation Love numbers $h$ fluctuate significantly from the earth model (i.e. the preliminary reference earth model), especially for the $h_{n1}^{32}$ component, and these changes in $h_{n2}^{12}$ and $h_{n0}^{33} - h_{n0}^{22}$ are relatively small. The vertical displacements derived from the inversion results agree well with the GPS vertical observations. The inverted dislocation Love numbers are considered to profile the regional structure which differs from the mean 1-D heterogeneous structure of the Earth, and the corresponding Green's functions of four independent dislocation sources describe a more reasonable seismic deformation field.

Simulation of nonlinear vibration responses of cab system subject to suspension damper complete failure for trucks

The strong vibration responses of the cab system can be restrained by the damper force and the friction of the suspensions for trucks. After the failures of dampers, especially in the case of the complete failure, the anti vibration effect of the friction is prominent. However, the nonlinear vibration response characteristics of the cab subject to the damper complete failure have not been revealed. In order to reveal the nonlinear vibration response characteristics, a dynamic model of the cab system was established and its vibration equations were given. The friction forces existing in the suspensions were determined by the bench test. The influences of the friction forces on the cab vibration under different amplitude harmonic inputs were investigated when the dampers completely fail. The cab vertical displacement changes with the excitation amplitude and the vibration represents various motion states, including the periodic motion, the quasi-periodic motion, and the chaotic motion. The simulation results show that when the dampers fail, the proper friction forces help to suppress the quasi-periodic motion and the chaotic motion of the cab and to reduce the amplitude of the periodic motion. The proper friction forces can make the cab movement far away from the chaos area. They also help to avoid the fatigue damage of the cab floor and suspension parts to improve the service life of the suspension parts and to reduce the maintenance cost of the cab suspensions.

Influence of Metro Tunnel Excavation on Deformation of Existing Pedestrian Underpass in Changzhou Railway Station Platform

In order to predict the impact of Changzhou Metro Line 1 passing through the pedestrian underpass of Changzhou Station in Shanghai-Nanjing Intercity Railway, FLAC3D software is used to simulate the excavation of the left and right subway tunnel lines step by step. The influences of existing and non-exiting pedestrian underpass on subsurface settlement are compared, and the deformation and stress distribution of the pedestrian underpass are analyzed. Additionally, the numerical results are verified by filed monitoring. The calculation and monitoring results show that the existence of the pedestrian underpass causes a relatively obvious “barrier” effect, which makes the vertical displacement changes with increasing of depth, and consequently causes the uneven vertical displacement. The tunnel excavation mainly causes the inclination of the pedestrian underpass, the floor deformation of the escalator channel, and the deformation difference occurs at the interface between escalator channel and pedestrian underpass; the existence of tunnel has little influence on the stress change of the pedestrian underpass. However, in order to protect from the concentration of stress, it is necessary to focus on monitoring the place where has a large stress during construction, such as, the right interface between pedestrian underpass and escalator channel, and the right exit of escalator channel.

Fault models for the Bodrum–Kos tsunamigenic earthquake (Mw6.6) of 20 July 2017 in the east Aegean Sea

We investigate a fault model for the shallow, strong (Mw6.6) tsunamigenic earthquake of 20 July 2017 with source area in the east Aegean Sea between Bodrum peninsula (Turkey) and Kos Isl. (Greece). Fault plane solutions are consistent with the regional active tectonics indicating normal faulting striking about E–W. A relocated hypocenter of the main shock was obtained and the rupture time-space history for two alternative fault solutions dipping either to the south or to north was approached by inverting P-waves recorded at teleseismic (30°–90°) distances. In both fault solutions the seismic moment calculated corresponds to magnitude Mw = 6.6 while the earthquake had total rupture duration of less than 10 s. The maximum co-seismic slip was close to the hypocenter ∼1.6 m and ∼2.2 m for the south and north dipping faults, respectively. Close to the surface co-seismic slip of ∼0.3 m was calculated. Our analysis of Sentinel satellite InSAR images showed ground deformation fringes indicating ∼13 cm vertical displacement change between the North and South coasts of the Karaada islet. This result is in line with our preference of the south dipping fault, supported primarily by GPS displacements, regional tectonics, aftershock activity and tsunami observations, although results of InSAR inversion fit equally well both solutions.

Coupling Vibration Research on Vehicle-Bridge System

Take vehicle running through a long-span cable-stayed bridge as an example to study the vibration rule of vehicle and bridge in the process of vehicles running on the large span bridge. Vehicle-bridge coupling numerical analysis model is established to study the changing rule of vertical displacement of the vehicle, vehicle wheel vertical contact force, the vertical displacement of the bridge and the impact coefficients of bridge while different quality of vehicles running on the bridge. The results show that, the heavier the vehicle, the greater and the more obvious wave of the vertical displacement change of bridge main-span across. The heavier the vehicles, the more obvious the change of the vertical displacement and torsion angle of cable-stayed bridge main-span across.

The Scaffold-Articular Cartilage Interface: A Combined In Vitro and In Silico Analysis Under Controlled Loading Conditions.

The optimal method to integrate scaffolds with articular cartilage has not yet been identified, in part because of our lack of understanding about the mechanobiological conditions at the interface. Our objective was to quantify the effect of mechanical loading on integration between a scaffold and articular cartilage. We hypothesized that increased number of loading cycles would have a detrimental effect on interface integrity. The following models were developed: (i) an in vitro scaffold-cartilage explant system in which compressive sinusoidal loading cycles were applied for 14 days at 1 Hz, 5 days per week, for either 900, 1800, 3600, or 7200 cycles per day and (ii) an in silico inhomogeneous, biphasic finite element model (bFEM) of the scaffold-cartilage construct that was used to characterize interface micromotion, stress, and fluid flow under the prescribed loading conditions. In accordance with our hypothesis, mechanical loading significantly decreased scaffold-cartilage interface strength compared to unloaded controls regardless of the number of loading cycles. The decrease in interfacial strength can be attributed to abrupt changes in vertical displacement, fluid pressure, and compressive stresses along the interface, which reach steady-state after only 150 cycles of loading. The interfacial mechanical conditions are further complicated by the mismatch between the homogeneous properties of the scaffold and the depth-dependent properties of the articular cartilage. Finally, we suggest that mechanical conditions at the interface can be more readily modulated by increasing pre-incubation time before the load is applied, as opposed to varying the number of loading cycles.

Использование технологии SBаS для обработки многопроходной серии радарных изображений

The paper deals with the processing of radar images obtained by multi-pass shooting of the same area. It is proposed to use the Small Baselines Subset (SBaS) method to assess and reveal the dynamics of earth surface displacements in mining areas using vertical displacement maps. The method was tested on Cosmo-SkyMed radar data of the cities territory like Leninsk-Kuznetsky, Polysayevo and Belovo for the period from 2011 to 2014. The results of our survey, which helped to identify areas of subsidence and uplift of the earth's surface in these areas and the average rate of vertical displacement changes are adducer.

The ground deformation field induced by a listric thrust fault with an overburden soil layer

The surface deformation field induced by a listric thrust fault with a thick, overburden soil layer is studied in this paper by the finite element method (FEM). The results show: (a) The maximum slip induced by the buried fault is not located at upper tip of the fault, but below it. (b) The vertical displacement changes remarkably near the fault, forming a fault scarp. With the increase of the soil layer thickness, the height of the scarp is decreased for the same earthquake magnitude. (c) The strong strain zone on the surface is localized near the projection of the fault tip on the ground surface. The horizontal strains in the zone are in tension above the hanging wall and in compression above the foot wall, and the vertical strains in the zone are vice versa, which is favorable for tensileshear, compression-shear fissures above hanging wall and foot wall, respectively.