scholarly journals Soil compaction caused by harvest and logging operations in eucalyptus forests in coarse-textured soils from northeastern Brazil

2017 ◽  
Vol 41 (2) ◽  
pp. 191-200 ◽  
Author(s):  
Maria Luiza de Carvalho Andrade ◽  
Diego Tassinari ◽  
Moacir de Souza Dias Junior ◽  
Ricardo Previdente Martins ◽  
Wellington Willian Rocha ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Bulk Density ◽  
Soil Compaction ◽  
Bare Soil ◽  
Northeastern Brazil ◽  
Plant Residue ◽  
Planted Forests ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
The Impact

ABSTRACT Planted forests occupy more than 6.5 million ha in Brazil, where harvest and logging operations are performed with increasingly heavier machinery, increasing the risk of soil compaction. Soil compaction can be avoided if soil load bearing capacity is not exceeded, what makes it important to assess both the soil strength and the impact of different operations. The aim of this study was to evaluate the load bearing capacity of some coarse textured soils (two Hapludult and one Haplorthod) in two soil horizons (BA and B), from northeastern Brazil; and to assess the impact of harvest and logging operations performed with harvester and forwarder. Although the Haplorthod presented higher load bearing capacity in both the BA horizon (for the whole moisture range) and the B horizon (for higher water contents), it suffered the greatest soil compaction. Traffic with the harvester resulted in soil compaction in both the BA and the B horizons, but the increase in bulk density was higher on the later, reaching 18.7% in the Haplorthod. The forwarder traffic intensity and the presence of plant residue cover significantly affected the occurrence of soil compaction. In the BA horizon, the increase in soil bulk density for different forwarder traffic intensities was 3 passes ~ 6 passes < 12 passes ~ 16 passes. The increase in bulk density was higher in the Haplorthod, reaching 32% after 16 forwarder passes over bare soil. Significant linear regressions were obtained from the number of forwarder passes and the increase in bulk density.

scholarly journals Soil compaction during harvest operations in five tropical soils with different textures under eucalyptus forests

2018 ◽  
Vol 42 (1) ◽  
pp. 58-68 ◽  
Author(s):  
Paula Cristina Caruana Martins ◽  
Moacir de Souza Dias Junior ◽  
Ayodele Ebenezer Ajayi ◽  
Ernesto Norio Takahashi ◽  
Diego Tassinari
Keyword(s):  
Bearing Capacity ◽  
Soil Compaction ◽  
Sandy Loam ◽  
Traffic Intensity ◽  
Compression Tests ◽  
Load Bearing Capacity ◽  
Undisturbed Soil ◽  
Load Bearing ◽  
Structure Degradation ◽  
Precompression Stress

ABSTRACT Traffic of farm machinery during harvest and logging operations has been identified as the main source of soil structure degradation in forestry activity. Soil susceptibility to compaction and the amount of compaction caused by each forest harvest operation differs according to a number of factors (such as soil strength, soil texture, kind of equipment, traffic intensity, among many others), what requires the adequate assessment of soil compaction under different traffic conditions. The objectives of this study were to determine the susceptibility to compaction of five soil classes with different textures under eucalyptus forests based on their load bearing capacity models; and to determine, from these models and the precompression stresses obtained after harvest operations, the effect of traffic intensity with different equipment in the occurrence of soil compaction. Undisturbed soil samples were collected before and after harvest operations, being then subjected to uniaxial compression tests to determine their precompression stress. The coarse-textured soils were less resistant and endured greater soil compaction. In the clayey LVd2, traffic intensity below four Forwarder passes limited compaction to a third of the samples, whereas in the sandy loam PVd all samples from the 0-3 cm layer were compacted regardless of traffic intensity. The Feller Buncher and the Clambunk presented a high potential to cause soil compaction even with only one or two passes. The use of soil load bearing capacity models and precompression stress determined after harvest and logging operations allowed insight into the soil compaction process in forestry soils.

scholarly journals Numerical and Experimental Study on Deficient Short Steel Tubes Strengthened with CFRP Under Compression

2019 ◽  
Author(s):  
Mohammad Reza Ghaemdoust ◽  
Omid Yousefi ◽  
Kambiz Narmashiri ◽  
Masoumeh Karimian
Keyword(s):  
Bearing Capacity ◽  
Numerical Study ◽  
Three Dimensional ◽  
Local Buckling ◽  
Steel Tubes ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Steel Columns ◽  
Repair Costs ◽  
The Impact

In view of development and repair costs, support of structures is imperative. Several factors, for example, design and calculation errors, absence of appropriate installation, change of structures application, exhaustion, seismic tremor, fire and natural conditions diminish their strength. In such cases, structures have need of rehabilitation and restoration to achieve their original performance. One of the most up to date materials for retrofitting is carbon fiber reinforced polymer (CFRP) that can provide an amount of restriction to postpone buckling of thin steel walls. This paper provides a numerical and experimental investigation on CFRP strengthened short steel tubes with initial horizontal and vertical deficiency under compression. Ten square and circular specimens were tested to study effects of the following parameters: (1) position of deficiency, horizontal or vertical; (2) tube shape, square or circular; (3) CFRP strengthening. In the experiments, axial static loading was gradually applied and for the numerical study three-dimensional (3D) static nonlinear analysis method using ABAQUS software was performed. The results show that deficiency reduces load-bearing capacity of steel columns and the impact of horizontal deficiency is higher than the impact of vertical deficiency, in both square and circular tubes. Use of CFRP materials for strengthening of short steel columns with initial deficiency indicates that fibers play a considerable role on increasing load bearing capacity, reducing stress at the damage location, preventing deformation caused by deficiency and delaying local buckling. Both numerical and experimental outcomes are in good agreement, which underlines the accuracy of the models adopted.

scholarly journals Fire Performance of Columns Made of Normal and High Strength Concrete: A Comparative Analysis

2016 ◽  
Vol 711 ◽  
pp. 564-571 ◽  
Author(s):  
Thomas Gernay
Keyword(s):  
Bearing Capacity ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Strength Loss ◽  
Fire Performance ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Strength Concrete ◽  
The Impact

The use of high strength concrete (HSC) in multi-story buildings has become increasingly popular. Selection of HSC over normal strength concrete (NSC) allows for reducing the dimensions of the columns sections. However, this reduction has consequences on the structural performance in case of fire, as smaller cross sections lead to faster temperature increase in the section core. Besides, HSC experiences higher rates of strength loss with temperature and a higher susceptibility to spalling than NSC. The fire performance of a column can thus be affected by selecting HSC over NSC. This research performs a comparison of the fire performance of HSC and NSC columns, based on numerical simulations by finite element method. The thermal and structural analyses of the columns are conducted with the software SAFIR®. The variation of concrete strength with temperature for the different concrete classes is adopted from Eurocode. Different configurations are compared, including columns with the same load bearing capacity and columns with the same cross section. The relative loss of load bearing capacity during the fire is found to be more pronounced for HSC columns than for NSC columns. The impact on fire resistance rating is discussed. These results suggest that consideration of fire loading limits the opportunities for use of HSC, especially when the objective is to reduce the dimensions of the columns sections.

scholarly journals Assessment of the soil compaction of two ultisols caused by logging operations

2008 ◽  
Vol 32 (6) ◽  
pp. 2245-2253 ◽  
Author(s):  
Moacir de Souza Dias Junior ◽  
Sérgio Ricardo Silva ◽  
Nadívio Souza dos Santos ◽  
Cezar Francisco Araujo-Junior
Keyword(s):  
Bearing Capacity ◽  
Bulk Density ◽  
Soil Compaction ◽  
Soil Samples ◽  
Threshold Levels ◽  
Eucalypt Plantation ◽  
Capacity Model ◽  
Preconsolidation Pressure ◽  
The Impact

The impact of wood loads on bulk density and preconsolidation pressure and of harvester and forwarder traffic on rut depth, bulk density and preconsolidation pressure of two Ultisols were examined in this study. Our objective was to quantify the threshold beyond which significant soil compaction and rutting would occur. This study was carried out in the county of Eunápolis, state of Bahia, Brazil, (16 º 23 ' 17 '' S and 39 º 10 ' 06 '' W; altitude 80 m asl) in two Ultisols (PAd2 and PAd3) with different texture classes, in experimental areas with eucalypt plantation. The study involved measurements at the wood load site and machine driving at specific locations in the forest during logging operations. The treatments consisted of one harvester pass and, 8, 16 and 40 passes of a fully loaded forwarder. Thresholds were established based on the rut depth and percentage of preconsolidation pressure values in the region of additional soil compaction defined in the bearing capacity model. The percentage of soil samples with values of preconsolidation pressure in the region of additional soil compaction indicated a greater susceptibility of PAd3 than of PAd2 to soil compaction. The threshold levels established here based on preconsolidation pressure and rut depth indicated that no more than eight forwarder passes should be allowed in loading operations in order to minimize soil compaction.

scholarly journals Finite Element Analysis of Load Bearing Capacity of a Reinforced Concrete Frame Subjected to Cyclic Loading

2016 ◽  
Vol 2 (5) ◽  
pp. 221-225 ◽  
Author(s):  
Mahdi Bamdad ◽  
Abdolreza Sarvghad Moghadam ◽  
Mohammad Javad Mehrani
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Impact Behavior ◽  
Reinforced Concrete Frame ◽  
Load Bearing Capacity ◽  
Element Analysis ◽  
Load Bearing ◽  
Concrete Frame ◽  
The Impact ◽  
Abaqus Software

Many methods have been developed in order to study the impact behavior of solids and structures. Two common methods are finite element and experimental method. The nonlinear finite element method is one the most effective methods of predicting the behavior of RC beams from zero-load to failure and its fracture, yield and ultimate strengths. The advantage of this method is its ability to make this prediction for all sections of the assessed RC beam and all stages of loading. This paper compares the experimental results obtained for a RC frame with the numerical results calculated by ABAQUS software, and plots both sets of results as hysteresis–displacement diagrams. This comparison shows that the numerical FEM implemented via ABAQUS software produce valid and reliable results for load bearing capacity of RC frames subjected to cyclic loads, and therefore has significant cost and time efficiency advantages over the alternative approach

scholarly journals Impact of the fire on the bearing capacity of the ordinary concrete used in reinforced concrete structures in Burundi. History and architecture

Vestnik MGSU ◽  
2021 ◽  
pp. 1567-1572
Author(s):  
Emmanuel Mikerego ◽  
Donatien Nduwimana
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Negative Impact ◽  
Heating Temperature ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Ordinary Concrete ◽  
The Impact

Introduction. This paper presents the results of an assessment of the impact of fire on the bearing capacity of the ordinary concrete, to be taken into account in the rehabilitation of fire-damaged reinforced concrete structures in Burundi. Materials and methods. Experimental samples of the ordinary concrete made respectively of coarse river aggregates and crushed coarse quarry aggregates were prepared and subjected to different heating temperatures (250, 350, 450, 600 and 900 °C) simulating the fire. After natural cooling, experimental samples were subjected to compression test; and diagrams showing the loss of the load-bearing capacity of the ordinary concrete used in reinforced concrete structures in Burundi were drawn. Results. Negative impact of the fire on the load-bearing capacity of the ordinary concrete occurs above of 350 °C of heating temperature. Concrete made of crushed coarse quarry aggregates loses 50 and 78 % of its bearing capacity at around 525 and 900 °C of heating temperature, respectively. Similarly, concrete made of coarse river aggregates loses 50 and 70 % of its load-bearing capacity respectively at 600 and 900 °C of heating temperature. An evaluation curve of the after-fire bea­ring capacity of the concrete used in reinforced concrete structures in Burundi is established. Conclusions. The negative impact of the fire on the load-bearing capacity of the ordinary concrete occurs above of 350 °C of heating temperature. Concretes made of crushed coarse quarry aggregates and concrete made of coarse river aggregates lose 50 % of its bearing capacity at around 525 and 600 °C of heating temperature respectively. Knowing the heating temperature that the fire-damaged reinforced concrete structure has undergone is indispensable in deciding on its demolition or rehabilitation.

scholarly journals Failure Assessment of Embankment Dam Elements: Case Study of the Pirot Reservoir System

2022 ◽  
Vol 12 (2) ◽  
pp. 558
Author(s):  
Dragan Rakić ◽  
Milan Stojković ◽  
Damjan Ivetić ◽  
Miroslav Živković ◽  
Nikola Milivojević
Keyword(s):  
Bearing Capacity ◽  
Grout Curtain ◽  
Strength Analysis ◽  
Embankment Dam ◽  
Load Bearing Capacity ◽  
Element Analysis ◽  
Load Bearing ◽  
Reservoir System ◽  
The Impact

The paper presents a functionality investigation of the key dam elements based on finite element analysis. A detailed analysis of filtration processes, dam strength, and the surrounding rock mass was conducted. Dam elements whose potential damage could jeopardize the normal functioning of the embankment dam have been identified. A particular emphasis was placed on the analysis of dam elements that have been identified as weak points. A numerical analysis of the impact of individual grout curtain zone failure on leakage under the dam body, a strength analysis of the overflow section, as well as the analysis of the slope stability that can compromise the functioning of the spillway have been performed. To analyze the partial stability of individual structural elements, a new measure of local stability was introduced as the remaining load-bearing capacity. As a case study, the Zavoj dam, which is a part of the Pirot reservoir system in the Republic of Serbia, was used. Investigation revealed that local damage to the grout curtain will not significantly increase leakage under the dam body, the overflow section is one of the most robust elements of the dam, but the slope above the spillway can compromise the functioning of the overflow and thus the safety of the entire dam. Based on the analysis of the results of the remaining load-bearing capacity, the dependence of the spillway capacity on earthquake intensity has been defined. The established relationship represents a surrogate model for further assessment of dynamic resilience of the complex multipurpose reservoir system, within the scope of the advanced reservoir system management.

The Impact of Load Bearing Capacity of Airfield Pavement Structures on the Air Traffic Safety

2017 ◽  
Author(s):  
Mariusz Wesołowski ◽  
Krzysztof Blacha
Keyword(s):  
Bearing Capacity ◽  
Traffic Safety ◽  
Fundamental Problem ◽  
Weather Conditions ◽  
Air Traffic ◽  
Definite Function ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
The Impact ◽  
The Way

Airfield pavement is a marked and appropriately prepared surface of an airfield functional element that performs a definite function in aircraft operations. The structure of airfield pavement is most often composed of a set of layers whose task is to absorb and transfer loads coming from moving aircraft onto the ground in a way that ensures its definite durability. Structures of airfield pavements are designed for a definite exploitation period on the assumption of predicted volume and structure of the air traffic. Safety of air operations conducted by aircrafts on airfield pavements depends mainly on the state of bearing capacity of their construction. Due to the above, control tests of bearing capacity shall be periodically conducted, since information regarding the current state of an airfield pavement constitutes the basis for decisions concerning the types of aircrafts permitted to land and take off, traffic volume and dates of starting renovation or modernization works. In addition to loads generated by aircraft, on the condition of airfield pavement load bearing capacity is influenced by many external factors, including weather conditions. The ACN-PCN non-destructive method is currently used in the assessment of airfield bearing capacity, which has been introduced by ICAO (ICAO 2013). According to its assumptions, the airfield construction bearing capacity may be expressed in PCN or permissible number of air operations. The fundamental problem by measuring airfield pavements is to assume the correct computational model of a structure, which describes the way of cooperation and mechanical properties of individual layers. This paper contains the way of assessing and description of PCN as well as presentation of the possibility of expressing bearing capacity results by determination of permissible number of aircraft operations. There is also interrelation between PCN and the permissible number of aircraft operations presented in a graphic way.

Experimental Measurements of a Model of Pile, Slab and Raft Foundation

2014 ◽  
Vol 14 (2) ◽  
pp. 101-109 ◽  
Author(s):  
Kamil Burkovič ◽  
Vojtěch Buchta
Keyword(s):  
Bearing Capacity ◽  
Experimental Measurement ◽  
Civil Engineering ◽  
Experimental Measurements ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Raft Foundation ◽  
Pile Cap ◽  
Load Tests ◽  
The Impact

Abstract A design of the load-bearing capacity and settlement of a pilot base is usually based on the assumption that all of the load from the top of the building is transferred only by pilots. The influence of the adjacent connecting structures, which are in contact with the ground (pile cap, slab, block, belt, etc.), is usually ignored. The necessary data from the experimental measurement of the impact of these structures, concerning the overall bearing capacity of the foundations, was obtained on the testload device (Stand), in the area of Faculty of Civil Engineering, VŠB-TU of Ostrava. The progress of the experiment and the results of the load tests are listed in this paper

scholarly journals NEURINGER-ROSEINWEIG MODEL BASED LONGITUDINALLY ROUGH POROUS CIRCULAR STEPPED PLATES IN THE EXISTENCE OF COUPLE STRESS

2020 ◽  
Vol 60 (3) ◽  
pp. 259-267
Author(s):  
Yoginibahen Devendrasinh Vashi ◽  
Rakesh Manilal Patel ◽  
Gunamani Biswanath Deheri
Keyword(s):  
Bearing Capacity ◽  
Couple Stress ◽  
Load Capacity ◽  
Continuum Theory ◽  
Type Equation ◽  
Stress Effect ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Closed Form Solutions ◽  
The Impact

This study intents to scrutinize the impact of ferrofluid in the presence of couple stress for longitudinally rough porous circular stepped plates. The influence of longitudinal surface roughness is developed using the stochastic model of Christensen and Tonder for nonzero mean, variance and skewness. Neuringer-Roseinweig model is adopted for the influence of ferrofluid. The couple stress effect is characterized by Stoke’s micro continuum theory. The modified Reynolds’ type equation is stochastically averaged and solved by no-slip boundary conditions. The closed form solutions for load bearing capacity and film pressure are obtained as a function of different parameters and plotted graphically. It is perceived that the load capacity gets elevated owing to the combined influence of magnetization and couple stress when the proper choice of roughness parameters (negatively skewed, standard deviation) is in place. Porosity and roughness (positively skewed) adversely affect bearing’s performance. The graphical and tabular analysis shows that there is a significant growth in load bearing capacity compared to the conventional lubricant case.

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