Deck Length Research Articles

Experimental and Numerical Investigations for Impact Loading on Platform Decks

Experimental measurement and numerical simulations were carried out for investigating the impact loading behavior of platform decks under regular and irregular wave actions. In the numerical simulation section, a full-scale numerical wave tank was established using STAR-CCM+ software. A decreased tendency can be observed for an increased relative length of platform when the incident wave length is double the deck length. The increased deck height can also decrease impact loading on the platform, which is due to the platform being far away from the incident wave. Impact loading on the deck decreases with the increase in inclination angle, which can be explained by the deck bottom being directly exposed to the incident wave at negative inclination angles. Finally, the variation tendency of impact loading on platform decks under irregular wave actions is similar to that under regular wave actions, including the averaged values and significant values.

Effect of Deck Length on Ground Vibration in Dragline Bench Blasting Using Artificial Intelligence Methods

Effect of Deck Length on Ground Vibration in Dragline Bench Blasting Using Artificial Intelligence Methods

Analysis of Blast Fragmentation Results of the Top Air Decking Method in Coal Mines

This research aims to find out what influences the results of blasting fragmentation in the top air decking method. The method used in this research is a quantitative method. The data collection techniques used in this research came from literature studies and field data collection. Processing data analysis is carried out by considering several factors, such as rock characteristics, fragmentation results, and digging time results. After analysis, it can be seen that the design for determining the ADF, ADL, and stemming values is adjusted to the hole depth and PF used so that the fragmentation and digging time obtained are better in order to increase production activities. Based on the research results, it was found that the factors that influence the fragmentation results from top air deck blasting are the powder factor, blasting geometry (burden and spacing), air deck length (ADL), stemming depth, and wet hole conditions. The greater the PF value used, the smaller the fragmentation resulting from blasting and vice versa. The greater the ADL value used, the stemming depth will decrease and there will be potential for stemming injection and producing boulders. More holes in wet conditions will potentially result in greater fragmentation as well. The optimal ADF value to use is 0.3. With an ADF value of 0.3, the ADL used is 0.4–1.47 meters, resulting in better fragmentation. The previous boulder percentage of 18% changed to 7% and the previous digging time of 11.87 seconds changed to 10.57 seconds.

Determination of the optimal modes of operation of the clover grater and scarifier KS-0.3 P during scarification

The article provides information about the features of the device, the quality of work of the prototype of a new 25...30 % more productive clover grater and scarifier KS-0.3 P in comparison with the analogue KS-0.2 P. KS-0.3P includes a drum-type wiping and scarifying device, a pneumatic separation device, a two-stage exhaust air purification system containing a cyclone and a fabric filter. The increase in the productivity of the new machine is achieved by increasing the diameter of the drum with a solid wiping surface to 0.45 m and the length of the oval deck with scarifying plates to 0.7 m. The solid grating surface of the drum is welded from steel rods of hexagonal profile No. 12 mounted on an edge. The deck covering the drum from below by 180° is made of round bars with a diameter of 10 mm and nine steel plates with a thickness of 2 mm and a width of 11 mm, evenly distributed along the length of the deck. When studying the technological process of clover grater and scarifier the method of mathematic planning of the experiment was used. The quality of scarification done was evaluated using the GOST 12038-84, GOST 12036-85 methodologies and additionally introduced indicator of variation of the number of germinated seeds. The material supply was regulated by the degree of opening of the flap in the loading hopper in the range from 0.2 to 0.4 t/h. The rotation frequency of the drum was changed by a frequency converter from 550 to 650 min-1. Eastern galega seeds met GOST 52325-2005 requirements. The experiments were carried out in three-fold repetition. As a result of an experimental study of the KS-0.3P cloverworm-scarifier during the scarification of the seeds of the Eastern galega, the ranges of the optimal drum rotation speed of 550... 650 min-1 and the material supply of 0.3... 0.4 t / h were determined, when the specified agrotechnical indicators were provided: the degree of scarification not less than 95.0 % and crushing not more than 1.5 %.

Numerical investigation on blast-induced rock fragmentation with different stemming structures

Stemming is one of the main concerns in blast of rock engineering due to its impact on explosion energy consumption and rock excavation performance. In this study, blast-induced rock fragmentation under different stemming conditions is numerically studied using combined numerical modelling and image processing. After careful determination the parameters of constitutive material models, the developed numerical model in LS-DYNA is verified based on the blast testing results including rock fracturing and fragment size distribution (FSD). The calibrated constitutive models are then used to model the pressure variation and rock disintegration produced by blasting with different stemming structures. The size data of simulated rock fragmentation are obtained by image-processing the cut surfaces of the numerical model with the program ImageJ, and the blast-created rock FSD is characterized using a three-parameter generalized extreme value function. The effects of the combination of explosive, air/sand deck and stemming on blast-induced rock fragmentation are quantitatively analysed, considering various stemming modes, stemming lengths and air/sand deck lengths. The results show that the blast-created fragment size decreases with an increase in stemming length, a decreasing in air/sand deck length, replacement of top stemming (stemming at borehole collar with air deck) with bottom stemming (stemming directly contact explosive) and alteration of air deck to sand deck, while the FSD range exhibits the opposite tendency. Bottom stemming is recommended for practical blasting due to its efficiency in rock fragmentation and robustness with respect to stemming length.

Hydrodynamic loads of the bridge decks in wave-current combined flows

This work uses a Large Eddy Simulation (LES) model and the Volume of Fluid (VOF) scheme to investigate the hydrodynamic loads on submerged rectangular decks in wave-current combined flows. The influences of current velocity, wave height, deck length, and blockage ratio on the wave loads are examined, and a modified Morison equation is used to predict the hydrodynamic forces on the deck. The simulation results demonstrate that the wave loads are linearly proportional to wave height H when H ≤ 0.4h, h is the water depth. By setting the reference velocity as Ur = (gH)1/2 for wave-induced flow, the hydrodynamic loads can be separated into a steady term (current-induced load) and an acceleration term (wave-induced load). The crucial hydrodynamic load comes from the surface pressures on the upper side of the decks, owing to the deck length being much larger than the deck thickness. In addition, the drag coefficient is independent of the wave height H, aspect ratio L/D, and the Keulegan-Carpenter number KC; while the lift coefficient depends on the submergence ratio S/D. Bridge engineers could easily use the modified Morison equation and the maximum drag coefficient CD = 2.73, lift coefficient CL = −2.05, the inertia coefficients CMx = 0.95 and CMz = 2.53 to compute the maximum loads against wave-current combined flows.

Application of Probabilistic Approach to Investigate Influence of Details in Time History of Temperature Changes on the HCF Life of Integrated Bridge Steel Piles Installed on Water

This research estimates the high-cycle fatigue (HCF) life of integrated concrete bridge installed on water due to temperature changes. To this end, CATIA software was used to geometrically model of a real-scale bridge. Next, thermal–structural coupling analysis was performed by finite element (FE) simulation in ANSYS WORKBENCH software. The comparison technique with experimental data was used to validate the simulation. Afterward, thermal analysis was performed due to air temperature changes in different modes, including the average monthly temperature changes (large variations) as well as the maximum and minimum monthly temperature changes (small variations). The results showed that the most changes in deck length and subsequent maximum deviation in the upper part of steel piles were related to the three warm seasons in the presence of the water. Eventually, a probabilistic approach was employed to find variable amplitude fatigue lifetime of the component based on the number of annual loading blocks. To achieve the high-accuracy response, the effective parameters of the proposed probabilistic approach, including order of Fourier series and the stress range, were optimized automatically. In addition, to obtain HCF behavior of raw material, axial tension–compression fatigue tests were performed on the standard specimens fabricated from steel piles. The results revealed that considering small variations in the calculation of structural fatigue life led to a 550% reduction in life compared to structural analysis due to large variations. In addition, the obtained results were compared with the finite element results.

Sensitivity of Tsunami Uplift Impact to Wharf Properties

To elucidate the tsunami-wharf interaction (e.g., flow field and pressure distribution), a numerical study was carried out to simulate a wharf subjected to a tsunami bore. A dam-break-like tsunami bore was simulated by modeling a gate-reservoir system. Five sections (reservoir, wet-bed, transitional, dry-bed and wharf model sections) were established to investigate the generation, propagation, stabilization of dam-break-like tsunami bore and impact on the model. The bore characteristics on the wet and dry bed were extracted; tsunami pressures and the flow field around the wharf model were presented. Validation against a laboratory model study showed that the computed pressure on the wharf was more accurate with a mild wharf slope than a steep wharf slope (less than 20% errors for 20 to 50°). The flow motion in the numerical flume consisted of the generation (0.5 s), stabilization (1.0 s), propagation (2.5 s) and impact stages (2.5 s). The flow velocity fields for the tsunami bore partly depended on the bed conditions due to momentum exchange between the tsunami bore and still water. The tsunami bore impacts on the wharf consist of four stages (front-climbing, front-hitting, water accumulation and quasi-steady), with the highest uplift pressures (5.5-6.7 kPa) occurring in the front-hitting stage when the bore first reached the wharf deck. The average tsunami uplift pressures exerting on the deck decreased with increasing deck length, deck-slope gap and slope surface roughness implicating three tsunami energy dissipation factors in the wharf design.

A CFD Numerical Study to Evaluate the Effect of Deck Roughness and Length on Shipping Water Loading

Shipping water events that propagate over the decks of marine structures can generate significant loads on them. As the configuration of the structure may affect the loading behaviour, investigation of shipping water loads in different structural conditions is required. This paper presents a numerical investigation of the effect of deck roughness and deck length on vertical and horizontal loads caused by shipping water on a fixed structure. Systematic analyses were carried out of isolated shipping water events generated with the wet dam-break method and simulated with OpenFoam Computational Fluid Dynamics toolbox. The numerical approach was validated and then the shipping water loads were examined. It was found that, as roughness increased, the maximum vertical and horizontal loads showed a delay. As the deck length reduced, the vertical backflow loads tended to increase. These results suggest it may be worthwhile examining the behaviour of shipping water as it propagates over rough surfaces caused by fouling, corrosion, or those with small structural elements distributed on them. Moreover, the effect of deck length is important in understanding the order of magnitude of loads on structures with variable deck lengths, and those which have forward and backflow loading stages.

Blast Vibration and Fragmentation Control at Heavily Jointed Limestone Mine

The presence of structural inhomogeneity in a rock mass in the form of joints, fractures, bedding planes is a very common phenomenon. These discontinuities have a great influence on rock fragmentation as explosive energy is significantly affected by it. The extent of these discontinuities also has a great influence such as the thickness of the joint interfaces which varies from very tight joints to open ones. The amount of energy (or stress) generated by explosives, transmitted through the joints and energy can be passed over the interface resulting in poor fragmentation. The paper is based on the challenges faced during the study at Sangmania and Birhauli limestone mines to achieve the desired fragmentation as the rock formation of the area is dominated by joints and layered bedding. Experimental practices viz. drilling of holes, drill pattern designs, delay intervals and charging of explosives (with or without deck) have been performed to achieve desired fragmentation. Fifty blasts have been conducted at different quarries of Sagmania and Birhauli mines to determine the effect of both joint spacing and orientation on rock fragmentation. Two hundred thirty-six ground vibrations data have been recorded and compared for different prediction equations for better control on ground vibration. The in-hole velocities of detonation of explosives were monitored and optimal deck length and deck types were optimized to improve the fragmentation. The in-situ block size and blasted block size were determined to evaluate the efficiency of blasting.

Response of full-height frame integral abutments subjected to seismic motions

As a new type of bridge, integral bridges can significantly reduce long-term maintenance costs, and their application is encouraged in many countries. However, there is great uncertainty regarding the dynamic performance of full-height integral abutments during earthquakes. This paper presents the findings from a dynamic numerical simulation on a typical full-height frame integral bridge abutment. The influences of peak acceleration, bridge deck length, and abutment height are investigated. The effect of a mitigation method, i.e., installation of a compressible layer behind the abutment, is also discussed. The results highlight the effect of the rigid connection between the deck and the integral abutment, which will transfer the very large inertial force of the bridge deck to the abutment top and cause strong dynamic interaction between the abutment and the backfill. The traditional Mononobe-Okabe method adopted in current bridge abutment design codes cannot provide a reasonable prediction as to the dynamic earth pressure behind integral abutments, leading to unsafe designs. Although a compressible layer can reduce the dynamic earth pressure, the deformation and bending moments of the abutment will increase as a result of the much lower restraint provided by the compressible layer during earthquakes.

Parametric study of nonlinear wave loads on submerged decks in shallow water

This study is concerned with calculations of nonlinear wave loads on submerged, horizontal decks in shallow water. Solitary and cnoidal wave loads on submerged decks are determined by use of the Level I Green–Naghdi (GN) equations. Results of the GN equations are compared with the linear theory, CFD, and with available laboratory measurements. Variation of the horizontal and vertical wave-induced loads and the overturning moment on submerged decks is studied through an extensive parametric study. In total, 240 cases are considered for cnoidal waves and 84 cases for solitary waves. The variable parameters include the wave height, wave period, deck submergence depth and deck length. Based on the parametric study results, two empirical, design-type equations are suggested for estimating the vertical and horizontal forces on submerged decks. Results of the empirical equations are compared with the available laboratory measurements and CFD calculations and good agreement is observed. Examples are provided to demonstrate the use of the empirical equations for prototype cases. The parametric study and the empirical equations provide engineers with the preliminary determination of wave loads on submerged decks.

Evaluation of reinforcement layout on the serviceability of MSE walls supporting footings

Mechanically stabilised earth (MSE) walls are becoming an increasingly common means of supporting footings, particularly those that support bridge superstructures. A verified numerical model employing finite-element (FE) analysis was used to investigate the influence of non-uniform reinforcement spacing on the performance of footing surcharged MSE walls. The effects of reinforcement density were evaluated under two scenarios: a ‘top-down’ approach where reinforcement spacing density is progressively increased from the top of the wall downwards and a ‘bottom-up’ approach where the spacing density is progressively increased from the toe of the wall upwards. Lateral deformation of the wall face, footing settlement and reinforcement strain were evaluated for varying conditions. Moreover, the development of shear mechanisms within the reinforced soil was evaluated. For MSE walls supporting footings, placement of closely spaced reinforcements in the upper portion of the wall was found to be more beneficial. Alternatively, when MSE walls do not support any surcharge, placing dense reinforcement near the toe is the most beneficial. Tailoring reinforcement spacing to MSE wall function can result in economic benefits by reducing the required bridge deck length or reducing the required reinforcement quantities. This study quantified the impacts of reinforcement configuration on service-state behaviour.

A study of cut blasting for one-step raise excavation based on numerical simulation and field blast tests

Over the past several decades, raise excavation has been widely employed in underground mining, civil engineering and military engineering. One-step raise excavation with burn cuts, where all the boreholes are pre-drilled and detonated at one time and no workers need to be underneath the freshly blasted and dangerous ground, is an important and promising method in raise excavation. Cut parameters, especially the parameters of prime cut which used empty hole as a free surface and swelling space, have significant influence on the effect of raise formed. In this study, two small-scale experimental methods, spiral hole spacing method and observation hole method, are designed to determine the prime cut parameters such as hole spacing (L), stemming length (Ls1, Ls2) and air deck length (La) which are normally determined by empirical formula. In order to study the feasibility of the two methods, numerical analysis and experimental tests are conducted in V zone of Sandaozhuang molybdenum mine (SMM), in which there are large numbers of underground goafs need to be controlled by filled raise. The Riedel–Hiermaier–Thoma (RHT) material model, which considers compression damage and tension damage effect under blasting loading, is employed in the LS-DYNA software to study the rock damage zone. Meanwhile, the field tests are carried out according to the two small-scale experimental methods. The comparison results show that the damage zone of numerical simulation has a good agreement with the experimental data. Further, the optimal prime cut parameters obtained from experimental tests are applied in one-step filled-raise excavation, and a 23 m raise that meets the design requirements is formed through the proposed technology. The results indicate that these cut parameters determined by the small-scale experiments are suited for one-step raise excavation. This study can provide two simple field experiments to determine the important prime cut parameters of one-step raise excavation.

Soil behaviour around the stub abutment of an integral bridge and buried piles in the contraction state

The change in the deck length under temperature load affects the upper part of integral bridge abutments and causes abutments rotation. The deck contraction makes the abutment move away from the backfill and causes a failure wedge. To prevent the failure wedge, a new method has been proposed. In this method, the inhibition of integral bridges under contraction is done by cables connected from each abutment to the buried piles outside the bridge along the abutments. In the analysis, the behaviour of soil around the abutment and buried piles is an important parameter which has a great influence on the results. In this paper, the soil behaviour around a laterally loaded stub abutment and buried piles was studied on laboratory stub abutment models using the PIV (particle image velocimetry) method. The PIV analysis was carried out to obtain the deformation pattern and shear strains of the soil around the stub abutment and buried piles. The effects of piles number and soil – pile interaction on the soil deformation pattern were investigated. The results showed that the use of buried piles connected by the cable avoided creating a failure wedge in the backfill.

Geotechnical Problems of Botan Bridge Piers Construction (Siirt, Turkey)

The Botan Bridge in Siirt (Turkey), now under construction, will carry a road across the River Botan and the lake which will be created by the Pervari Dam, 180 m high. The bridge has two piers with height of 115.88 m, and the total length of deck is 450 m which is built in accordance with the free cantilever method. The paper deals with foundations used in Botan Bridge for dam reservoir crossing bridge structures. Some of the geotechnical problems of construction of these foundations are highlighted. The slope debris deposits and basement rocks being ophiolite and the metamorphic rocks (calc schist, chlorite schist and meta-sediments) contribute to the geotechnical problems. Ophiolite, calc schist and chlorite schist, contains significant percentage of chlorite, feldspars, carbonates and serpentinites; their effect needs to be assessed in the interpretation of pier foundation construction and slope stability calculations. For this purpose, in situ and laboratory tests have been performed. Ophiolitic rock mass properties are an important factor for slope stability of rocks and foundation construction.

Service-state behavior of reinforced soil walls supporting spread footings: a parametric study using finite-element analysis

Reinforced soil has become a common means of retaining soil and supporting spread footings due to ease of construction and cost-efficiency. However, the behavior of these structures under service state conditions is inherently complex and dependent on the selection of design factors. Factors that govern design include earth pressures, settlements and reinforcement strains, but are not easily attained from closed form solutions. This study aims to provide insight into the complex behavior of reinforced soil walls surcharged by a discrete footing in context of these design factors, facilitating the development of a numerical model. A nonlinear elastic–plastic constitutive soil material model was calibrated to experimental plane strain test data, while the performance of a wall model was compared against full-scale laboratory testing of an identical geosynthetic-reinforced wall from prior literature, demonstrating satisfactory agreement. This agreement enabled a parametric study of the same wall model with a discrete spread footing evaluating the effects of reinforcement type and vertical spacing, footing location, footing dimensions, and toe restraint on lateral earth pressure distributions, wall deformations and reinforcement strains. The results of the study demonstrated that simplified consideration of only reinforcement type on service-state performance of reinforced walls neglects the effects of closely spaced reinforcements on behavior. Use of closely spaced reinforcements created increased earth pressures, but also reduced lateral displacement, footing settlements and reinforcement strains. Furthermore, it enabled achievement of equivalent service state criteria for footings located closer to the wall facing, potentially enabling increased right-of-way or reduced deck length when supporting a bridge superstructure.

MSE walls as bridge abutments: Optimal reinforcement density

Geosynthetics have become a common means of soil reinforcement in earth retention structures; however, the efficacy of its application can be enhanced dependent on use. Geosynthetic design often involves uniform spacing of reinforcements throughout a retaining structure. However, optimization of reinforcement spacing can have a significant impact on stability, especially when subjected to a finite surcharge, as demonstrated by a series of numerical simulations using Limit Analysis (LA). Use of a rigorous LA tool that employs an algorithm to computationally determine the critical collapse state allows for the determination of optimal reinforcement placement in Mechanically Stabilized Earth (MSE) walls based on both spacing and concentration – specifically at the toe or crest of the structure. The effects on stability are evaluated for two scenarios: (1) a “top-down” approach where reinforcement spacing density is progressively increased from the top of the wall downwards and (2) a “bottom-up” approach where the spacing density is progressively increased from the toe of the wall upwards. Presented within this study are the results of comprehensive parametric analysis varying reinforcement spacing, reinforcement strength and footing location, highlighting the stability benefits of top-down and bottom-up reinforcement density approaches. Placement of dense reinforcements near the crest of surcharge-supporting walls had a notable benefit for stability, while placement of dense reinforcements at the toe improved stability for walls without a surcharge. Hence, reinforcement spacing tailored to specific wall functions may provide significant economic benefits when considering reduced reinforcement needs, lessened tensile strength requirements, or shortened bridge deck length based on surcharge placement – all by concentrating reinforcement density at a specific height of a structure.

Limit Analysis Optimization of Design Factors for Mechanically Stabilized Earth Wall-Supported Footings

Increasingly in the past few decades, mechanically stabilized earth (MSE) walls have been a common choice for earth retention solutions due to their ease of construction, cost-effective design, and flexibility. However, limit state capacity of footings atop a MSE structure, such as a bridge abutment, is a complex and non-intuitive stability problem dependent on factors like reinforcement layout and strength, location of footing, and failure mechanism. In order to evaluate the effects of these factors, a parametric study was performed utilizing a robust tool in the framework of limit analysis of plasticity. It demonstrates the effect of the parameters on bearing capacity and optimized reinforcement efficiency, all in context of an existing MSE wall-supported bridge abutment. It is shown that closely spaced reinforcement layouts allow for more efficient reinforcement behavior and improved bearing capacity nearer to the wall facing, while inverse, detrimental trends were observed for wider reinforcement spacing. The implications of this analysis illustrate that an optimized approach involving footing location, reinforcement strength, and reinforcement spacing allow for reduced bridge deck length requirements. This clearly has economic consequences. The optimization of these design factors is especially applicable to MSE wall-supported bridge abutments since the location of the footing affects expensive elements such as length of girders. Fundamentally, this work adds to the limited existing knowledge of bearing capacity of footings on top of MSE walls.

Ambient vibration testing of Berta Highway Bridge with post-tension tendons

The aim of this study is to determine the dynamic characteristics of long reinforced concrete highway bridges with post-tension tendons using analytical and experimental methods. It is known that the deck length and height of bridges are affected the dynamic characteristics considerably. For this purpose, Berta Bridge constructed in deep valley, in Artvin, Turkey, is selected as an application. The Bridge has two piers with height of 109.245 m and 85.193 m, and the total length of deck is 340.0 m. Analytical and experimental studies are carried out on Berta Bridge which was built in accordance with the balanced cantilever method. Finite Element Method (FEM) and Operational Modal Analysis (OMA) which considers ambient vibration data were used in analytical and experimental studies, respectively. Finite element model of the bridge is created by using SAP2000 program to obtain analytical dynamic characteristics such as the natural frequencies and mode shapes. The ambient vibration tests are performed using Operational Modal Analysis under wind and human loads. Enhanced Frequency Domain Decomposition (EFDD) and Stochastic Subspace Identification (SSI) methods are used to obtain experimental dynamic characteristics like natural frequencies, mode shapes and damping ratios. At the end of the study, analytical and experimental dynamic characteristic are compared with each other and the finite element model of the bridge was updated considering the material properties and boundary conditions. It is emphasized that Operational Modal Analysis method based on the ambient vibrations can be used safely to determine the dynamic characteristics, to update the finite element models, and to monitor the structural health of long reinforced concrete highway bridges constructed with the balanced cantilever method.