Wood Column Research Articles

Lateral performance of circular wooden columns reinforced with high-performance bamboo-based composite

This study researches the lateral performance of wooden columns strengthened with the non-damage reinforcement method, which used high-performance bamboo-based composite (HPBBC) materials and steel strips to form a hollow reinforcement system and then jacketed and reinforced the wooden columns. Six wooden columns strengthened by non-damage reinforcing methods were subjected to low cyclic loading tests under horizontal loads with a constant axial pressure ratio. The horizontal loads, displacements, and strain distributions of different locations at the column root were measured. The experimental results showed that the reinforcement method improved the lateral performance of wooden columns by about 4.96–58.54 %. Owing to the protective effect of the reinforcement system, the development of tensile damage to the wooden columns was delayed, but the breaking location was still the column root. In addition, the energy dissipation capacity and equivalent viscous damping coefficient of the reinforced wooden columns were significantly improved. The deformation of the strengthened column root conforms to the plane section assumption, while the deformation of the reinforcement system was lagged due to the absence of colloid and shear connectors between the wooden column and the reinforcement system. A bending capacity equation for the reinforced wood column was deduced based on the strain distribution in the damaged section. The error between the calculated and experimental results was within 13 %.

2-DOF Preview Feedforward Sliding Mode Controller for the Control of Multivariable Process with Dead Time

This paper proposes a 2-DOF preview feedforward sliding mode controller (PFFSMC), which has a combination of feedback and feedforward terms in the sliding surface, for controlling the multivariable process with dead time, for both set point tracking and disturbance rejection. The proposed controller is applied for the control of the Wood and Berry binary distillation column having the composition of top and bottom products. The performance of the 2-DOF PFFSMC is compared with that of the 1-DOF preview sliding mode controller. The proposed controller delivered better responses for set point tracking and for disturbance rejection. The performance of the proposed 2-DOF PFFSMC is compared with the other controllers reported in the literature and, it was found that there was a significant reduction in the settling time by more than 76%, without any overshoot in the closed loop response. The proposed controller was robust against ±5% parametric uncertainties in gain, time constant, and dead time when these uncertainties were considered alone and together. The stability of the proposed controller was verified using the Lyapunov stability criterion.

Integrated separation-electrochemical detection device based on wood column for online identification of enantiomer

Integrated separation-electrochemical detection device based on wood column for online identification of enantiomer

Analysis of Force Deformation Characteristics of Aged Wood Column Components with Consideration of Targeted Hybrid Fine Modeling

ABSTRACT This study establishes a refined model of wooden column members, with the aim of studying more accurately the force deformation characteristics of column members under the influence of aging. The service life of each layer of columns was predicted by calculating the load-bearing capacity of each layer under the influence of aging; a hybrid 3D model with integrated triangular network model and parametric model was established; the location of the column point where the maximum displacement occurred at each level of the second to fifth layer columns was obtained through the real-time monitoring system; the deformations of columns M2W23-S, M3W23-S, M4W23-S, and M5W23-S were analyzed using numerical simulations, and the accuracy of the hybrid 3D model was verified. The results of the study show that all the columns in the second to fifth layers no longer have a compressive load-bearing capacity between 3300 and 3500 years; a hybrid 3D model that integrates the triangular mesh model and the parametric model to reflect more realistically the existing morphology of the wooden column elements; the locations of the column points where the maximum displacement occurred in each of the second to fifth layer columns are M2W23-S, M3W23-S, M4W19-S and M5W16-S, respectively, of which the deformation of column M2W23-S is more serious, and the column needs to be reinforced and protected as soon as possible.

Mechanical properties of BFRP-reinforced glued laminated wood hollow round column under eccentric pressure

The FRP-wood column elements are lightweight and high performance, meeting the social demand for sustainable construction. In this study, a basalt fiber reinforced polymer (BFRP) reinforced glued laminated wood hollow round column structure is proposed. Small eccentricity compressive tests and numerical simulations were carried out on glued wood hollow columns strengthened with BFRP to study the effect of BFRP arrangement on the mechanical properties of glued wood hollow columns with constant material, size and eccentricity. All samples are compression side of the wood first yielded, and then some samples tensile side of the end of the wood fracture or the central section of the wood was pulled off, which belongs to the typical compression bending failure and conforms to the characteristics of small eccentric compression. The compressive load capacity of the wood column after BFRP pasting was increased by 3.4%∼30.54%, and the lateral flexural stiffness was increased by 1.44%∼23.86%. Meanwhile, pasting BFRP at the end and middle of the wood column can effectively restrain the compression deformation at the end and bending deformation at the middle, and obtain higher load capacity and lateral flexural stiffness. The numerical simulation results agree well with the experimental results and can effectively characterize the mechanical properties of BFRP-reinforced glued laminated wood hollow round column under eccentric loading conditions.

Experimental Study on the Axial Compression Performance of Glued Wood Hollow Cylinders Reinforced with BFRP

The present paper investigates the impact of basalt fiber reinforced polymer (BFRP) on the axial compression performance of glued wood hollow cylinders. This study aims to facilitate the application of BFRP in the field of structural reinforcement of glued wood hollow columns. Ten glued laminated wood hollow columns of the same size were designed and placed into five groups (ZC1 and ZRC2 to ZRC5), of which one group (ZC1), with a total of two pure wooden columns, was not arranged with BFRP, and the remaining two wooden columns in each group were arranged with BFRP at different distances. The destruction mode, ultimate load capacity, load–displacement curve, load–strain curve, and ultimate load capacity–total area of the BFRP paste curve of each specimen were obtained by conducting axial compression tests on five groups of wood columns reinforced with different basalt fiber cloths, which revealed the damage mechanism, the relationship between the ultimate load capacity and total area of BFRP paste, and pointed out the most effective area ratio. The test results show that the destruction mode of axially pressed, glued, laminated wood hollow columns is typical compression buckling damage, mainly manifested as follows: the wood at the middle or end of the specimen under pressure first buckles; then, with the increase in load, the specimen is crushed; at this time, the maximum ultimate bearing capacity of each specimen is in the range of 296.77~375.85 kN, the maximum longitudinal displacement is in the range of 2.77~3.38 mm, and longitudinal cracks appear at the end. It is worth noting that the growth rate of the ultimate bearing capacity varies with the increase in the total area of the BFRP paste. When the total area of the BFRP paste is less than a 3.2 × 105 mm2 range value, the growth rate of the ultimate bearing capacity is faster, and then, the growth rate gradually becomes slower. The optimum BFRP paste area ratio can be taken as k = 0.59. The ultimate bearing capacity after reinforcement increases from 11.06% to 26.65% compared with the pure wood column. According to GB50005-2017, “wood structure design standards” improve the hollow wood column bearing capacity calculation method and fit the BFRP reinforced hollow wood column’s ultimate bearing capacity calculation formula; the errors are within ±10%, which can provide a reference for the practical application of BFRP in the field of reinforcing glued wood hollow cylindrical structures.

Fractional PID controller based on biggest log modulus tuning method with MOPSO optimization for distillation column

The main contribution of this work is to design a fractional order proportional integral derivative (FO-PID) controller by combining the biggest log modulus tuning (BLT) method and multi-objective particle swarm optimization (PSO) algorithm for the control of the challenging multivariable systems. The parameters of the integer proportional integral (PI) controller are designed preliminary using BLT method. The derivation parameter, the fractional integrator and the fractional derivation parameters is formulated as an optimization problem with many objective functions as minimizing the integral square error (ISE), integral time absolute error (ITAE) and objective function which contain the ISE, overshoot and settling time using PSO algorithm. An example of wood and berry distillation column is treated in this paper. A comparison between integer BLT, integer PSO, big bang-big crunch (BB-BC) algorithm, TLBO method and the proposed fractional BLT-PSO method is carried out. The simulation results using MATLAB/Simulink show the efficiency and merits of the proposed method for such systems.

Decoupled Fractional Order Filter with PID Controller Design for Multivariable Distillation Column System

The main objective of this research work is the design of decentralized PID controller with fractional order filter for strongly connected multivariable distillation column system. Wherein, the major contribution of this paper is the proposition of compensators for the decoupling process, in addition to extending the application of the proposed approach from Single-Input Single-Output (SISO) systems into Multi-Input Multi-Output (MIMO) systems. More precisely, the proposed idea is based on eliminating the strongly interactive terms between the inputs and outputs of the multivariable distillation column systems so that, the separated multi-loop parts can be treated as a set of SISO subsystems, which have an equivalent dynamic of the whole original system. Thereafter, a PID controller with a fractional filter has been introduced to the decoupled subsystems in decentralized scheme in order to improve the control system robustness. Two multivariable systems have been carefully considered in this paper; the first is a theoretical Two-Input Two-Output (TITO) system while the second is the Wood and Berry distillation column. The obtained results have confirmed the superiority of the proposed approach over the two degrees of freedom technique, which is based on Internal Model Control method. Indeed, the proposed approach has reduced the dynamic error, the settling time, and the rise time. Furthermore, the designed decentralized PID controller with fractional filter has demonstrated rejection to structured perturbation from one loop to another.

Compressive performance of steel-timber composite L-shaped columns under concentric loading

Steel-timber composites (STCs) have emerged in the construction of large-span structures and multistory buildings. In this paper, a novel L-shaped column fabricated using STC (L-STC) was proposed. The L-STC column consisted of equal-leg angle steel and glulam. The angle steel was bonded inside the glulam. Twenty-two L-STC columns were tested under axial compression and compared with four L-shaped glulam columns as control groups. Parameters including wood species, steel ratios and column lengths were considered. The failure modes, stiffness, load-carrying capacity and ductility of the L-STC columns were analyzed. The test results demonstrated that L-STC columns displayed a (near) full composite action. The short L-STC columns failed due to crushing failure while the long L-STC columns failed due to global buckling. The stiffness and load-carrying capacity of the L-STC columns were enhanced by more than 56% and 33%, respectively. Increasing the width of the angle legs was recommended to achieve a higher load-carrying capacity. Furthermore, a finite element analysis was developed and validated. The load distribution on components of the L-STC columns was presented, and restraining effects of the timber on steel were analyzed and discussed. It was found that enhancing the timber grades, column lengths or reducing the steel ratios offered preferable lateral restraint of timber on steel.

Crushing mechanical responses of natural wood columns and wood-filled composite columns

Composite structures with high crushing characteristics are drawing great attention in the structuraldesign due to their excellent lightweight and high strength. This paper aims to investigate mechanical responses of natural wood columns and wood-filled aluminum or carbon fiber reinforced plastics (CFRP) columns under axial crushing load. Parametric studies are performed on the material of the external wall, the grain orientations (longitudinal, tangential, and radial) and the growth rings’ gradient of the wood (Toona Sinensis) by experimental test. Experimental results show that grain orientations of the wood and the material of the external wall have remarkable influences on the collapse mode and the crushing force, and the wood column with longitudinal grain orientation presents the best energy absorption. In addition, the plastic buckling process, collapse mode and crushing force response of wood-filled composite specimens are comprehensively investigated under axial crushing load. It is found that wood-filled aluminum composite columns present progressive collapse mode and higher crushing force level than wood-filled CFRP composite columns. Furthermore, the synergistic behavior between the external wall and wood filler is evaluated. This study offers insights on designing novel energy absorber with high crashworthiness capacity by applying novel wood fiber materials.

Monitoring and Analysis of Ancient Building Columns on the Basis of Relative Dynamic Method

During the service period of ancient building structures, due to the cumulative development of local damage to load-bearing members such as columns, the structural strength and stiffness will decrease, which may lead to catastrophic accidents. The traditional damage recognition method based on modal parameters is sometimes not effective. In this study, the vibration analysis combined with the relative dynamic method is used to analyze the damage of the wooden columns of the ancient building. The dynamic damage identification experiment was performed on a single wooden column. The effects of compressing the wooden column, crack length, and application of axial pressure on the natural frequency of the wood column were explored. The natural frequency of the wood column was determined by data acquisition and signal processing (DASP) software, and the damage of the component was evaluated by analyzing the change in the natural frequency obtained under different states. Results of the relative dynamic method showed that the damages can be evaluated by observing the change in the natural frequency. However, determining the damage position and the damage form was impossible. Then the mode shapes at different frequencies were obtained by processing the time domain signal, Fast Fourier Transform (FFT) calculation, and simultaneously using the Eigensystem Realization Algorithm (ERA). It is able to detect the damage of the ancient building components without damage, adding experiments to verify it, and enriching the application of the relative dynamic method theory. According to the variation law of the vibration mode animation, the location of the crack is generally concluded.

Automated synthesis of multivariate QFT controller and pre-filter for a distillation column with multiple time delays

In the refining and chemical industry, distillation is one of the prime processes and is a multivariable control problem, which involves interaction amongst several control loops and exhibit dead time in the dynamic behavior. The analysis and controller design of processes inheriting dead time is a challenging task, and the presence of plant uncertainties and disturbances makes it challenging to exert quality control over time. In this paper, a template and bounds free approach is explored for the simultaneous synthesis of quantitative feedback theory (QFT) based robust controller and pre-filter for Wood and Berry distillation column with multiple time delays. This presented method simplifies the QFT controller synthesis for MIMO systems and eliminates the need of ‘Schauder fixed point theory’ to express the m×m MIMO system into analogous m2 MISO plants before the QFT controller synthesis. Using the presented approach, an optimal MIMO QFT controller and pre-filter are synthesized in a single step, which else conventionally follows a long sequential design process. In the presented approach, the QFT controller design problem has been posed as an optimization problem and is solved using genetic algorithm. The work has been compared with the work already reported in literature. The designed multivariate QFT controller efficiently mitigate the effect of parametric uncertainties, satisfy the design requirements in a very tight envelope, minimize the interaction amongst the control loops and offers improved the disturbance rejection.

Study on Seismic Capacity of Single-story and Brick-concrete Structure Building in a Rural Area of Southern Guangxi

Based on the investigation and analysis of the brick-concrete and single-story houses in a rural area of southern Guangxi, the author established four different overall models of single-story house according to a certain proportion by ABAQUS-a software of finite element analysis, so as to analyze the seismic response of brick-concrete and single-storey buildings in this area under the action of 6-magnitude frequent earthquake. The results show that, under the action of 6-magnitude frequent earthquake, if the single-storey and brick-concrete house is built without reinforced concrete, its wood beam support or column support cannot reduce the stress concentration of the structure obviously;the displacement deviation between the top and the middle of the outer wall can be reduced when the wood beam is used as the support between the inner wall and the outer wall.

FUZZY CONTROLLER OF MODEL REDUCTION DISTILLATION COLUMN WITH MINIMAL RULES

In this paper the control of a binary distillation column is described. This control is done with fuzzy logic, one with PI- like fuzzy controller and the other with modified PI fuzzy controller, using the minimal rules for fuzzy processing. This work is focused on model reduction of Wood and Berry binary distillation column to get the best performance. It is desired to minimize the rules in order to reduce the computation time to make a faster decision. Comparisons will be made between two versions of fuzzy controllers utilizing reduced rules to verify the outputs. The controlled variables are top composition with high concentration and bottom composition with low. To demonstrate the performance of the fuzzy PI control schemes, results are compared with a classical PI controller and optimal methods, like Differential Evolution (DE), Invasive Weed Optimization (IWO).The proposed structure is able to quickly track the parameter variation and perform better in load disturbances and also for set point changes. Then all the processes of the distillation column with it? s fuzzy controllers are simulated in MATLAB software as the results are shown.

Inverted Decoupling 2DoF Internal Model Control for Mimo Processes

In general, the multiple-input-multiple-output (MIMO) system is the main method of process control in industry. However, the interaction between variables in the process is a challenge when designing controllers for the system. Strong interaction worsens system performance. Inverted decoupling plays an important role in reducing interaction in the process. Internal model control (IMC) is the controller used in this research. A one degree of freedom (1DoF) IMC controller is only able to provide a good response to set-point tracking, and has a slow response to disturbance rejection. Therefore, a controller that has a good response to set-point tracking and disturbance rejection is a two degrees of freedom (2DoF) IMC. The tuning method uses maximum peak gain margin (Mp-GM) stability criteria based on the uncertainty model. In this study, a reduction in interaction was realized by the addition of inverted decoupling to the 2DoF IMC control scheme. The Wardle & Wood and Wood & Berry column distillation models are given as illustrative examples to demonstrate the performance of the inverted decoupling 2DoF IMC control scheme. A comparison is made of the IAE values of 1DoF IMC, 2DoF IMC, decoupling 2DoF IMC, and inverted decoupling 2DoF IMC, with inverted decoupling 2DoF IMC showing the lowest IAE value.

Mechanical properties of wood columns with rectangular hollow cross section

Abstract A rectangular hollow wood column made of Spruce-Pine-Fir (SPF) lumbers was developed, for the purpose of improving the utilization efficiency of timber. The present work conducted experimental investigations of the columns under centrically and eccentrically compression. A wide range of slenderness ratios of columns and eccentricities of loads was considered to carefully examine the failure modes in columns. The results indicated that combined material failures and buckling failures were observed for the intermediately slender columns under axial compression, while buckling failures were observed for the long columns. The ultimate strength of columns under axial compression significantly decreased with the increase of slenderness ratios. The predicted results by the tangent modulus theory closed to those of experiments. The bending failure, which underwent a pronounced nonlinear process, was the major characteristic of the intermediately slender column with an eccentric compressive load. Typically, the load carrying capacity of columns showed a decreasing trend with an increasing in eccentric ratios. Both the secondary bending and material nonlinearity were important factors that impacted the nonlinear response of the column. An analytical model was proposed for evaluating the load carrying capacity of the rectangular hollow columns under the interaction between compression and bending. There was good agreement between the results of the experiments and calculations.

Hygrothermal Behaviours of Wood Column Exposed to Outdoor Weather During One Month

Hygrothermal Behaviours of Wood Column Exposed to Outdoor Weather During One Month

The predictive research of ancient wooden building internal defects compressive bearing capacity based on nondestructive testing methods

131 small specimens and 10 scaled wood column specimen (including 2 complete specimen and 8 with different defect locations and sizes and the type is core cavity) are made with the reference to Building Formulas to research the ancient wooden building internal defects compressive bearing capacity prediction. Some researches on the relationship between the small specimens wave resistance modulus and mechanics, nondestructive testing and internal defects wood column compressive bearing capacity prediction as well as dangerous section judgment and so on. The test result suggests that there is a significant positive correlation between the wave resistance modulus and the compressive strength (r2 = 0.635), which is more accurate than single parameter; internal defect specimens with various locations have an impact on overall compressive bearing capacity and with the defect sectional area expanding, the compressive bearing capacity decreases continuously, the cross-sectional area of the defect is proportional to the attenuation of the relative resistance value; nondestructive method can better predict wood column ultimate compressive bearing capacity and the error is predicted less than 10%. Nondestructive testing method can better determine the most dangerous section of the test piece compared with destruction morphology results. The wooden components quality can be safely evaluated on the premise that the originality of the ancient buildings is preserved and valid data references can also be provided for renovation and reinforcement of ancient buildings wooden components.

A New Point of View in Multivariable Controller Tuning Under Multiobjective Optimization by Considering Nearly Optimal Solutions

In this paper, we present the adjustment of controller parameters using multiobjective optimization techniques. Unlike other works, where only the Pareto optimal solutions are considered, we also consider the set of nearly optimal solutions nondominated in their neighborhood. These solutions are potentially useful for two reasons: 1) they are similar to the optimal solutions for the optimized objectives, and; 2) they differ significantly in their parameters. This last point makes them interesting, since they bring diversity and different characteristics to the set of solutions for analyzing in the decision stage. In problems of controller parameter adjustment, especially for multivariable processes, there are many conflicting objectives. To simplify the optimization problem and decision stage, it is common to aggregate some of the objectives, and so simplify the initial problem. In this scenario, some controllers that were optimal for the initial problem can become nearly optimal in the simplified case. When these controllers are nondominated in their neighborhood, they are especially interesting because they usually present a different trade-off for the initial objectives. For the calculation of nearly optimal solutions nondominated in their neighborhood, the evolutionary algorithm nevMOGA was used. In this paper, the usefulness of considering these solutions is revealed in two controller design problems: the Wood & Berry distillation column and the CIC2018 control benchmark.

Estimation of Credibility of the Results of Measuring Temperature within Specimens of Wood Columns Obtained During Fire Tests

Analysis of the results of experimental studies of wood columns mode of behaviour both having fire retardant coating based on OSB slabs and without any coating under standard time – temperature curve fire conditions was realized. An assumption was made that thermocouple wires could be positioned along isotherm at a distance of at least50 mmfrom measuring thermojunctions (otherwise disturbance of the structure of isotherm itself possible). Due to specific features of thermocouples positioning within the specimen, this assumption calls in question of credibility of the obtained results of temperature indices measuring. Bearing this in mind we prepared calculation scheme of the specimen of wood column under study. We have composed finite elements scheme of specimen under study for heat engineering calculations. We simulated temperature distributions within the wood column specimen section at various moments of time and substantiated the obtained results. It was revealed in the course of the study conducted that the obtained results were adequate for relative error was as small as ca. 4.5% and Fisher test did not exceed appropriate tabulated value. Thus, assumption made does not affect in general credibility of the results of measuring thermal values within the layers of specimens obtained during fire tests.