Force Of Rod Research Articles

Development of fiber Bragg grating vibration sensor for bidirectional monitoring of thin rod cantilever beam

Monitoring of vibration frequencies and forces in cables and suspension rods of bridges is crucial. In order to achieve high-precision and bidirectional low-frequency monitoring of cable force and suspension rod, in this work, a thin rod cantilever beam type FBG vibration sensor was developed for bidirectional monitoring based on theory, experiment, and finite element simulation. Firstly, elastic structure of the thin rod was analyzed, and the structural parameters of the sensor were optimized based on theoretical analysis and finite element simulation. Then, the frequency and sensitivity of the sensor were tested. The obtained test results showed that the resonant frequency of the sensor in the x/y direction was 48 Hz, sensitivity was 90.5/102.3 pm/g, and error in frequency was less than 2 %. Furthermore, the force in the cable measured by the sensor was verified through indoor tension tests. The test results showed that the maximum error in the force measured in the cable was 0.86 % relative to the actual tension in the cable, indicating high measuring accuracy of the developed sensor. Finally, the sensor was applied to monitor forces in actual engineering cables, where an error of 4.21 % was noticed, which further validated the accuracy and applicability of the sensor. The research results of the present would provide guidance for improving the ability of the bidirectional low-frequency FBG vibration sensors to measure low-frequency random vibrations.

Kajian Struktur Rangka Batang Jembatan Wailola Besar Kabupaten Seram Bagian Timur

The Wailola Besar Bridge, which is located in Bula District, East Seram Regency, has a Warren truss type frame structure. However, unlike the truss used on other bridges, the truss on the Wailola Besar bridge has a larger size than the others. Because the span of the Wailola Besar bridge is 80 m, while the span of other bridges using the Warren truss type is a maximum of 60 m. The larger size than the other trusses makes the Wailola Besar bridge have a different truss from other trusses. The length of each horizontal bar is 6.65 m, while the maximum length for other bridges is 5 m. Then the purpose of this study is to determine whether the truss structure of the Wailola Besar bridge is capable of carrying the loads acting on the bridge, the method used is with the help of the SAP-2000 program to determine the truss forces then controlled with allowable voltage. In order to know whether the structure is able to withstand the forces acting. From the results of calculations with the help of SAP-2000 the rod forces acting on the largest truss structure are 11066.881 KN at constant loading and 12222.547 KN at temporary loading and the stress that occurs is 1742.82 Kg/〖cm〗^2. at constant loading and 1924.81 Kg/〖cm〗^2. The stress that occurs in the truss does not exceed the allowable stress.

Effects of stiffeners on anchor rod flexural strength in column base-plate connections

The present paper reports results of a numerical investigation of the mechanical behavior of a column base plate connection subjected to an axial compression force and a bending moment. A three-dimensional nonlinear model was developed, using the Cast3M software, and validated against experimental data. In addition, the material nonlinearity as well as contact conditions between the different components of the connection were thoughtfully considered. Based on the validated model, an extensive parametric analysis was conducted to investigate the effect of stiffeners on the forces in the anchor rods. The results clearly indicate that the design approaches that consider only the tensile strength of anchor rods while neglecting the bending moments can lead to a poor estimation of the forces applied to these rods. They also suggest that adding stiffeners provides additional strength and reduces the anchor rod bending in one direction. However, it is important to note that the stiffeners also induce an additional moment in the opposite direction. This could make the anchor rod more susceptible to biaxial bending with tension. Furthermore, this study proposes a new specific shape of stiffener is suggested (cbp5). It was concluded that the proposed shape of stiffeners allows a more uniform distribution of forces and avoids excessive stress concentrations, effectively prevents the biaxial bending in the anchor rod.

Safety analysis of temporary anchorage system for immersed tube in Shenzhen–Zhongshan Link

In the construction of the Shenzhen–Zhongshan Link, a temporary anchorage system, distributed uniformly along the pipe wall, has been employed. To assess the safety and reliability of this system, a combined method utilizing numerical analysis and model experiments was applied to study the safety of the temporary anchorage system and the reliability of the tension rods. Firstly, an overall model of the caisson segment based on GINA rebound force was established to analyze the stress state of the entire system. Secondly, a comprehensive numerical analysis and model experiment verification were conducted for the single tensioning system, revealing its failure mode and safety margin. The results indicate that the tension rod systems are uniformly stressed at an average of 444 kN during underwater jointing, with a safety factor of 1.94. At this point, the maximum von Mises stresses appearing at the front plate corners and the lower edge of the U-groove, with stress values of 181.8 MPa and 172.4 MPa, and safety factors of 1.54 and 1.71, respectively. When the tension rod force reaches 940 kN, the tensioning system reaches its bearing limit, with initial yielding occurring at the front plate corners. Model experiments were conducted to verify the theoretical analysis results, under a test load of 444 kN, the stresses at the front plate corners and the lower edge of the U-groove were 159.6 and 195.9 MPa, respectively. As the test load increased to 940 kN, these stresses reached 390 and 389 MPa, exhibiting good agreement with the numerical analysis. Considering the uncertainty of loads and materials, a reliability analysis of the tension rods was conducted, yielding a reliability index of 4.34, meeting the secondary safety standard. Based on the comprehensive analysis, it can be concluded that the temporary anchorage system in the caisson segments of the Shenzhen–Zhongshan Link exhibits excellent safety margins.

Analysis of the Impact of Forces in Hanger Rods on Power Boiler Operation

Hanger rods intended for boiler suspensions on a metal structure require a special design approach that considers the total weight of the boiler structure that is to be carried. Unfortunately, a large reserve in the rods’ carrying capacity does not always guarantee the failure-free operation of a boiler. For this reason, it is very important to monitor the forces acting in the rods. Any negligence in this matter might cause a local excess of stresses in the boiler pressure part and result in periodic shutdowns of the boiler. Therefore, in order not to let this happen, adequate computational methods have to be developed. To date, the methods described in the literature and in design requirements have concentrated, first of all, on analyses of the boiler individual subassemblies or on small boiler units supported from the bottom at just a few points. The aim of this paper was to conduct a numerical analysis for a real high-capacity power boiler. The computations were performed based on experimentally measured forces in the hanger rods, and the results were verified by comparing the areas of stress concentration against the area where the boiler structure was regularly damaged.

Pump System Model Parameter Identification Based on Experimental and Simulation Data

In this paper, the entire downhole fluid-sucker rod-pump system is replaced with a viscoelastic vibration model, namely a third-order differential equation with an inhomogeneous forcing term. Both Kelvin’s and Maxwell’s viscoelastic models can be implemented along with the dynamic behaviors of a mass point attached to the viscoelastic model. By employing the time-dependent polished rod force measured with a dynamometer as the input to the viscoelastic dynamic model, we have obtained the displacement responses, which match closely with the experimental measurements in actual operations, through an iterative process. The key discovery of this work is the feasibility of the so-called inverse optimization procedure, which can be utilized to identify the equivalent scaling factor and viscoelastic system parameters. The proposed Newton–Raphson iterative method, with some terms in the Jacobian matrix expressed with averaged rates of changes based on perturbations of up to two independent parameters, provides a feasible tool for optimization issues related to complex engineering problems with mere information of input and output data from either experiments or comprehensive simulations. The same inverse optimization procedure is also implemented to model the entire fluid delivery system of a very viscous non-Newtonian polymer modeled as a first-order ordinary differential equation (ODE) system similar to the transient entrance developing flow. The convergent parameter reproduces transient solutions that match very well with those from fully fledged computational fluid dynamics models with the required inlet volume flow rate and outlet pressure conditions.

РОЗРАХУНОК АРКОВОЇ ДОРОЖНЬОЇ СПОРУДИ З ГОФРОВАНОГО МЕТАЛУ З УРАХУВАННЯМ ФОРМИ ГОФРУ

Introduction. The issue of calculation of an arched road structure made of corrugated metal on the basis of numerical modeling using the finite element method (FEM) using the actual cross-sectional parameters of metal corrugated structures (MCS) is considered. Problem Statement. In past years, for the calculations and tests of road constructions from MCS, a simple rectangular cross-section, equivalent in terms of bending stiffness to a corrugated profile, was considered. This was adopted to simplify calculations and research. Such an approach is also used in modern norms for the design of buildings with MCS. But this is not quite a correct simplification. Purpose. To show the possibility to avoid unnecessary convention and simplification of the calculation scheme and to obtain more correct and more informative results of the calculation of structures with MCS. Research methods and results. The purpose and tasks are realized by calculation-theoretical analysis and numerical modeling according to FEM using a specific example of calculating a road structure (small bridge) from the MCS. The calculation model is made according to the actual shape of the corrugations, without switching to the conventional simple rectangular cross-section of the arch elements, which are equivalent in terms of bending stiffness. The main design condition for strength in this work is the condition that the design load does not exceed the bearing capacity of the arch, as a component of the «building-soil» system.The bearing capacity of the structure in this work is considered as the sum of the arch's own bearing capacity (outside the soil) and the addition, which is provided by the elastic support of the embankment soil in response to the movement of the arch toward the soil. To determine the addition of bearing capacity due to soil resistance, the arch model is adopted as a «mechanism» with full hinges in the places of the greatest stresses and deformations of the arch. The geometric stability of the "mechanism" is ensured by additional rods that simulate the soil support by moving the arch. The forces in these rods must be corresponding to the equivalent resistance of the soil. The bearing capacity supplement is defined as the load on the arch, at which the forces in the additional rods are equal to the equivalent soil resistance of the embankment by the permissible movement of the arch toward the soil.

Seismic displacement analysis of slope reinforced by frame prestressed anchor rod structure

Instability of slope induced by earthquake seriously affects casualties and property losses and hinders earthquake rescue, so the study of slope displacement under earthquake is of great significance. For the slope reinforced by frame prestressed anchor rod structure under earthquake, the calculation method of slope displacement and axial force of anchor rod under seismic action were derived by combing Newmark method and limit analysis method. This method proposed in this paper comprehensively considers the amplification effect of earthquake acceleration on the slope surface, the inertial force of reinforce structure and the dynamic change of axial force of anchor rod. The solution program of this method was compiled in MATLAB and its rationality was proved by a numerical model in FLAC3D software. The results show the slope displacement calculated by the method proposed is consistent with the variation law of slope displacement obtained by traditional methods. Regardless of whether the anchoring force is considered or not, the slope yield acceleration obtained by this method is very close to the slope yield acceleration obtained by the Bishop method. The critical sliding surfaces obtained by the two methods are very close, and the sliding points are located at the foot of the slope. Compared with the Bishop method, this method can consider the amplification effect of seismic force on the free surface of the slope and the gravity of the supporting structure. Ignoring the change of the axial force of anchor rod will make the slope displacement larger, while not considering the amplification effect of the seismic acceleration on the slope surface and the gravity of the reinforce structure will make the slope displacement smaller. This method proposed in this paper comprehensively considers the above factors and is more accurate. In the process of landslide mass sliding, the axial force of the anchor rods increase gradually, and the growth rate of the axial force of the lower anchor rods are larger than that of the upper anchor rods. The increase of anchor rod prestress and elastic modulus will reduce the seismic displacement of the slope, and the increase of the dip angle of the anchor rod will increase the seismic displacement of the slope. The dip angle of the anchor rod should be minimized without affecting the grouting effect of the anchor rod.

A Laboratory Machine Verifying the Operation of a Hydraulic Rope Equalizer with Tensometric Sensors.

In mining machines with friction discs, but also in multi-rope traction elevators, it is necessary to distribute the applied tensile load, generated by the weight of the cage and counterweight, evenly in all cross-sections of the load-bearing ropes. Hydraulic devices used for this purpose can operate on the principle of Pascal's law. This article presents a structural design, a 3D model and an implemented solution of a laboratory device capable of simulating a practical method of evenly distributing the total weight of the load into partial tensile forces of the same size acting on a selected number of load-bearing ropes. The laboratory equipment uses two pairs of three steel cables of finite length for the simulations. During the experimental measurements, tensile forces derived from the tractive force of the piston rods, pushed into the bodies of the hydraulic cylinders by the pressure of the hydraulic oil supplied through the pipeline under the pistons of the hydraulic cylinders, were detected. The resulting amount of hydraulic oil pressure in the hydraulic circuit influenced by different values of the hydraulic oil pressures in the hydraulic cylinders and by the pressure in the supply pipe was experimentally studied on the laboratory equipment. Simulations were also carried out in order to detect the hydraulic oil pressure in the hydraulic circuit caused by the change in the different magnitudes of the tensile forces in the ropes. From the experiments carried out, it follows that with the appropriate choice of hydraulic elements and the design of the hydraulic circuit, the weight of the load, acting as the total pulling force in the ropes, can be evenly distributed (with a deviation of up to 5%) to all cross-sections of the load-bearing ropes. If the exact values of the hydraulic oil volumes under the pistons of all hydraulic cylinders are not known, it is not possible to calculate the pressure values in the hydraulic circuit when the valves of the hydraulic pipes are gradually opened.

Prediction of Sucker Rod-tubing Wear Depth in Surface Drive Screw Pump Production Wells

With the wide application of ground drive screw pump in the process of oil production, the wear problem of screw pump sucker rod-tubing is becoming more and more prominent. In order to systematically study the wear of the rod and tube of the screw pump production well and quantify the wear of the rod and tube, this paper establishes a calculation model of the contact force of the screw pump sucker rod by analyzing the force of the rod and tube string in the three-dimensional wellbore trajectory. Based on the indoor rod and tube wear simulation experiment, combined with the wear efficiency theory, a prediction model of sucker rod-tubing wear under different working conditions was established, and an example well calculation was carried out. The results show that the force of sucker rod is mainly affected by sucker rod size, submergence degree and other factors, and the wear of sucker rod and tubing is mainly affected by working time, rotational speed and wear efficiency. The research results can not only accurately carry out accurate quantitative calculation of downhole rod and tube wear, but also provide theoretical and technical basis for prediction of rod and tube wear depth.

Multi-Stage and Multi-Parameter Influence Analysis of Deep Foundation Pit Excavation on Surrounding Environment

As urbanization accelerates, deep excavation projects have become increasingly vital in the construction of high-rise buildings and underground facilities. However, the potential risks to the surrounding environment and the inherent complexities involved necessitate thorough research to ensure the safety of those engineering projects with deep foundation pit excavation and to minimize their impact on adjacent structures. This study introduces a multi-stage and multi-parameter numerical simulation method to scrutinize the construction process of deep foundation pits. This approach not only investigates the influence of excavation activities on nearby buildings and roads but also enhances the fidelity of simulation models by establishing a three-dimensional finite element model integrated with on-site investigated geological information. Therefore, the proposed method can provide a more holistic and accurate analysis of the overall impacts of the pit excavation process. To examine the feasibility and effectiveness of the proposed method, this study adopts the multi-stage and multi-parameter influence analysis approach for a real practical engineering case to explore the impact of excavation on the foundation pit support structure, nearby buildings, and surrounding roads. The foundation pit support’s maximum displacement was 8.64 mm, well under the 25 mm standard limit. Anchor rod forces were about 10% below the standard limit. Building and road settlements were also minimal, at 10.33 mm and 16.44 mm, respectively, far below their respective limits of 200 mm and 300 mm. This study not only validates the feasibility of design and construction stability of deep foundation pits but also contributes theoretical and practical insights, serving as a valuable reference for future engineering projects of a similar scope.

Heat and Mass Transfer Characteristics of Oily Sludge Thermal Desorption

Oily sludge is a loose material containing solid and multiple liquid components. Thermal desorption is an efficient method of disposing of liquids from oily sludge. Most existing studies have mainly discussed the effect of some external process parameters on thermal desorption, with little discussion on the heat transfer characteristics and the variation in the wet component mass of oily sludge under heating. Small-scale experiments have been performed to measure the rise in temperature and liquid phase content change of the sludge during heating. The temperature rise rate increases with material density and increases faster during the initial heating stage, while it slows down as the liquid phase evaporates. The adhesive shear stress is determined by measuring the pulling force of the test rod, which decreases with decreasing water content and increases significantly with decreasing oil phase content. Heat transfer and energy distribution models have been developed to calculate the rise in the temperature of materials and the evaporation of contained liquids. The heat and mass transfer processes are obtained from simulation calculations by taking the initial material with a mass content of 25% water and 10% oil under a heating temperature of 500 °C. When the heating time reaches 135 min, the drying region reaches the boundary of the test container, at which the material temperature exceeds 350 °C. During the evaporation of different liquid-phase components, there are multiple segments in the corresponding temperature curves. The processing time and heat source temperature can be reasonably determined by analyzing the temperature rise of the material, and the effect of the disposal of liquids from oily sludge can be predicted by analyzing the changes in liquid content. The results may guide the formulation of process parameters for engineering project schemes for oily sludge disposal.

Development and Experimentation of Intra-Row Weeding Device for Organic Rice

Weeds in paddy fields can seriously reduce rice yield. An intra-row weeding device with double-layer elastic rods was designed, considering the differences in mechanical properties between rice and weeds, which can press weeds into the soil and avoid damaging rice. The elastic force of the elastic rods can be adjusted by changing the position of the regulating mechanism to adapt to different weeding conditions. A measurement experiment was conducted to determine the variation rule of elastic force. The quadratic orthogonal rotation combination discrete element simulation experiment, which used weeding depth and weeding speed as experimental factors, and the amount of soil disturbance and the force of the inner and outer elastic rod in the horizontal and vertical directions as experimental indicators, was conducted to study the interaction between the weeding device and the soil. The optimal weeding parameters were obtained: the weeding depth was 15 mm, the weeding speed was 0.9 m/s. The field experiment, which used the various parameters of the weeding device as experimental factors and the weeding rate and damaging seedling rate as experimental indicators, was conducted to determine the weeding effect. The experimental results showed that the optimal position of the regulating mechanism was 270 mm, with a weeding rate of 80.65% and a damaging seedling rate of 3.36%. The weeding rate can be increased by at least 11.18% by adjusting the regulating mechanism to a suitable position under the same weeding conditions. This study can provide a reference for research on weeding machinery for organic rice.

FEATURES OF BENDING OF CURVILINEAR ABSOLUTELY ELASTIC BARS

In construction mechanics, the linear theory of bending is used to calculate deflections of beams. It gives an approximate result, but it is quite acceptable for practice, since the deflections of the beams are small compared to their length. In the case of significant deflections of the rods, when the curvature of the elastic axis is significant, a nonlinear theory is used. It is based on the position of resistance of materials, according to which the curvature of the elastic axis is directly proportional to the applied moment and inversely proportional to the stiffness of the rod. Such types of elastic bending are present in agricultural tillage equipment. Thanks to the elasticity of the rods, which can be working bodies or connect the working bodies to the frame of the machine, pulsating loads are extinguished. Bars in the free state can have an initial curvature of the elastic axis, which can be constant or variable. One end of the rod is rigidly attached to the machine frame, and the other is under the influence of the applied force. If the curvature is constant, that is, the elastic axis of the rod is an arc of a circle, then the deformation will be the same regardless of which end of the rod is attached to the frame. For rods with a variable curvature of the elastic axis, this is important. The following cases are considered in the article, corresponding calculations were made on the basis of which the shape of the elastic axis of the rod after its bending was found. Curvilinear rods of variable curvature have a different value at the ends. In this regard, the shape of the elastic axis under the action of the tracking force of the pinched rod will depend on which end it is pinched. The moment under which the elastic axis of the rod is deformed depends on the shoulder, that is, on the length of the arc of the elastic axis.The length of the arc of the curve can increase only in one direction from the reference point. If the rod is clamped at the opposite end, then the direction in which the shoulder grows, i.e. the length of the arc, must be changed. For this purpose, a method of solving this problem is proposed, which allows you to take any section of a curved rod and examine it for bending by the following force when one or the opposite end is pinched.

ЗАВИСИМОСТЬ ОСНОВНОЙ ЧАСТОТЫ СОБСТВЕННЫХ КОЛЕБАНИЙ ПЛОСКОЙ ШПРЕНГЕЛЬНОЙ ФЕРМЫ ОТ ЧИСЛА ПАНЕЛЕЙ

A scheme of a statically determined planar truss with downward braces and truss reinforcement is proposed. The problems of the lower and upper boundaries of the main natural frequency of free oscillations of the structure are solved. A model with masses concentrated at the nodes is adopted. To find the formula for the dependence of the oscillation frequency limits on the number of panels, the Dunkerley and Rayleigh methods are used. The expressions for the forces in the truss rods are found from the solution of the system of linear equilibrium equations for all nodes. To obtain the matrix of the system of equations, Maple computer mathematics operators are used. The rigidity of the structure is calculated using the Maxwell – Mohr formula. The sequence of solutions obtained for trusses with different numbers of panels is generalized by induction to an arbitrary case. For the coefficients of the formula in the desired solution, homogeneous linear recurrent equations are compiled and solved. The obtained solution is compared with the numerical solution of the problem of the oscillation spectrum of a structure with many degrees of freedom. It is shown that the first frequency of the spectrum is close to its analytical estimate. With an increase in the number of panels in the truss, the accuracy of the derived formulas increases.

Wind induced coupling effects of transmission tower-line system at microtopography

The coupled and uncoupled Dynamic Finite Element Models (DFEMs) of the transmission tower-line system consisting of two towers and three spans of conductors and ground wires were built at the windward and crosswind slope of a cosinoidal hill. The acceleration ratios of mean wind profiles of cosinoidal mountains were summarized from previous studies, then the mean wind profile over the windward, crosswind and leeward slopes were revised. The wind loads acting on the transmission tower-line system were calculated based on the revised profile. The wind-induced dynamic responses of the coupled and uncoupled DFEMs were detected, and the coupling effects on reaction force of hanging points, displacements and accelerations at the tower top, axial forces of main rods and wind-induced vibration coefficients were analysed. The results show that due to the lack of the TMD-like effect, the uncoupled system is more sensitive to wind load and has significant wind-induced vibration compared to the coupled system, making the three-dimensional force of the hanging point, displacements and accelerations at the tower top, axial forces of main rods increasing, but the wind-induced vibration coefficients change little. Generally, the coupling effects of the tower-line system are significant. Ignoring it will make the structural design of transmission towers conservative.

Application of neural network technologies to load monitoring in aircraft structure bearing elements

Economic efficiency in the operation of aircraft local air lines (LA) can be improved by increasing the awareness of the loading and aircraft structure integrity, with the subsequent adjustment of the maintenance program in accordance with the actual operating conditions. The allowance for specific features of loading load-bearing elements at transport aircraft during particular operations provides a significant extending in the safe life (in some cases, by several times). However, at the moment, load monitoring systems in the aviation industry have not yet been implemented universally. The implementation of the well-known approaches developed for monitoring and analyzing loads requires significant changes in the programs and procedures for maintaining airworthiness, including the need to install additional sophisticated measuring equipment. We propose an alternative approach to existing methods of load monitoring without using additional measuring equipment. The main stage is formation of the relationship between the flight parameters recorded by the standard on-board recorder and the loading parameters, which are determined by computational and experimental methods as a result of processing strain gauge data. A sufficient bulk of the strain data is usually obtained during the flight tests at the certification stage. Testing of this technique is considered with reference to the example of the loads in the elements of high lift devices of aircraft flaps. The average error in the estimates of the forces in the connecting rods of the inner flaps does not exceed 6%. The results obtained make it possible to determine with the acceptable accuracy the individual accumulated damageability of an aircraft structure and to assess the residual safe life. The presented approach is a part of the methodological framework necessary for the development and implementation of modern means of analyzing the integrity of the structure, implemented on the basis of on-board monitoring systems of local airlines aircraft.

ФОРМУЛА ДЛЯ НИЖНЕЙ ОЦЕНКИ ПЕРВОЙ ЧАСТОТЫ СОБСТВЕННЫХ КОЛЕБАНИЙ ФЕРМЫ ТРЕХГРАННОЙ БАШНИ

A scheme of a statically determinate tower-type spatial truss is proposed. Three lateral faces of the structure have double diagonal lattices, from below the truss rests on six racks and three additional horizontal lateral braces. The problem of the first natural frequency of free oscillations of the structure is solved. The inertial properties of the truss are modeled by the masses in its nodes. Each mass has two horizontal degrees of freedom. To obtain an analytical expression for the dependence of the lower limit of the oscillation frequency on the number of panels, the approximate Dunkerley method is used. The forces in the truss rods are found from the solution of the system of equilibrium equations for the nodes. The matrix of the system of equations is compiled in the Maple computer mathematics system. The rigidity of the structure is determined using the Mohr integral. A series of solutions obtained for a different number of panels is generalized to an arbitrary case by induction. For sequences of coefficients in the solution, linear recurrent equations are compiled and solved. The analytical solution is compared with the numerical solution of the problem of the vibration spectrum of the structure. It is shown that the first frequency of the spectrum is higher than the analytical estimate by no more than 30%. The accuracy of the estimate depends to a greater extent on the number of panels. As the number of panels increases, the accuracy of the resulting estimate increases. A trusses with only an even number of panels are considered. It is noticed that with an odd number of panels, the determinant of the system of equilibrium equations of nodes vanishes, which indicates the kinematic degeneration of the structure.

Shaking table test on suspend-dome structure with the center-hung scoreboard under three-dimensional seismic

In order to meet the demand of watching games, the LED display, i.e., the center-hung scoreboard, has been widely used in large stadiums. To investigate the mechanical properties of the suspend-dome structure with the center-hung scoreboard under the action of earthquake, a dynamic scaled model with a geometric similarity ratio of 1:20 was designed. And the shaking table test was performed to study the seismic performance under the actions of 8 degree frequent, seismic precautionary and rare earthquakes. The acceleration, displacement and internal force responses under three-dimensional seismic were analyzed. The results show that the Z-directional acceleration amplification factors of the reticulated shell vertex region are significant and decrease fastest under actions of rare earthquakes, which is the weak point of the model. The influence of the center-hung scoreboard on the structure cannot be ignored in the study of seismic performance. The vertical displacement is the largest in the center and gradually decreases from inside to outside. The maximum displacement under actions of frequent earthquakes is 2.061 mm. The maximum displacement under actions of seismic precautionary earthquakes is 1/556, the maximum displacement under actions of rare earthquakes is 1/242, both of which satisfy the requirement of seismic specifications. The maximum internal force of the ring rod first decreases and then increases from the center to the surroundings. The internal force of the radial rod gradually increases from the edge to the center. Under actions of rare earthquakes, the center-hung scoreboard has more influence on the internal force of the rod. The accuracy of the finite element modeling method is verified by comparing the simulation results and test results of the scaled model, and the reliability of the scaled model is verified by comparing the simulation results of the scaled model and the prototype structure. The structure does not collapse under actions of 8 degree rare earthquakes and does not show apparent failure. The seismic principle that “the structure hasn’t damaged under frequent earthquake, repairable under precautionary earthquake, and doesn’t collapse under rare earthquake” is reached, thus the structural design of the Lanzhou Olympic Sports Complex is reasonable.

Perbandingan Hasil Analisa Perhitungan Rangka Kuda-Kuda Kayu Dengan Menggunakan SAP-2000 dan Metode Titik Buhul

This research is a study that discusses the comparison of the results of the analysis of the calculation of the forces on the wooden framework using the Structure Analysis Program-2000 (SAP-2000) and method of joint. The value of each force of vertical bars, horizontal bars, tensile bars, and compression members at each point of the wooden framework will be calculated on three wooden framework spans with spans of 7m, 9m, and 11m. Comparison of the results of the calculation of the value of the rod force from the two methods will be compared to see the efficiency of the calculation analysis of the two methods. From the results of the calculation of the method of joint and the Analysis of Structure Analysis Program-2000 (SAP-2000) in calculating and analyzing the value of each vertical bar force, horizontal bar, tension member, and compression member, the difference between each rod force is at (0- 0.51) kg. This shows that the calculation analysis using the Structure Analysis Program-2000 (SAP-2000) is faster and more efficient in calculating each bar force.