Deck Load Research Articles

Experimental and Numerical Studies on the Ultimate Bending Strength of Welded Plated Grillage with Combined Openings

Plated grillage with combined openings was susceptible to complex failure behaviors as the main load-bearing structure of the superstructure on passenger ships subjected to deck loads. Additionally, the deformation and stresses generated during the welding of the plated grillage complicated the prediction of its failure behavior. In this case, a new partitioned inherent strain method and nonlinear finite element method were used to simulate the welding and loading process, and experiments were designed and carried out to make comparisons, unveiling the influence regulations between the failure behavior of the structure and the loading condition, the initial welding state. This research on the failure mode analysis of plated grillages could provide references for the optimization of the structural form of plated grillages and the cargo loading scheme on the deck of a real ship.

Examining error-contaminated, long-span bridge buffeting vibration by Stochastic Differential Equations

This paper summarizes the development of an analytically-based and numerically-implemented algorithm for the analysis of uncertainty propagation in aeroelastic systems. The term “uncertainty” is utilized to describe either simplifications in the modeling of the fluid–structure interaction mechanism or the effect of experimental errors, for example emerging during wind-tunnel tests. The algorithm is applied to study the dynamic response of long-span bridges. This study provides, by theoretical derivations, estimation of the stationary joint-probability distribution of the generalized bridge response, accounting for perturbations in the buffeting loads. The formulation includes physical states, fluid–structure interaction states and a random variable, which quantifies the errors in the span-wise correlation of the buffeting deck load. A 1200m span bridge is used for illustration of the numerical algorithm.

Shaking table test and numerical investigation of seismic response of pile-supported wharves with batter piles

Batter piles control displacement of wharves and offshore platforms by absorbing most earthquake and berthing loads because of their high lateral stiffness. Nevertheless, structural failure caused by stress concentrated in the pile caps has been reported in past earthquakes. The present paper investigates the seismic performance of wharf models with and without batter piles using 1 g shaking table tests with harmonic excitation as well as real earthquake records. Sensitivity analysis was performed by studying the effect of the deck load, shaking frequency, embedment depth of the pile and the relative density of the soil on horizontal displacement and acceleration of the deck. A numerical investigation was conducted using 3D finite element method to evaluate the role of the pile inclination angle on the behavior of the pile-supported system. The results of dynamic analysis quantitatively indicated the defects in the batter piles under different conditions. It was also concluded that, although the amount of deck displacement decreased when the inclination angle was reduced, the axial force generated in the batter piles showed no upward or downward trend and maximized at a specific angle.

A Parametric Study on Effect of Wave Height, Water Depth and Support Conditions on Behaviour of Offshore Jacket Structure

Fixed offshore jacket structures are constructed for facilitating oil/gas exploration and production. These structures and their foundations are designed to resist large vertical and lateral loads. Various factors including water depth, wave height and support conditions would affect the response of jacket structures. However, few studies have focused on understanding the response of offshore jacket structure due to variation in these factors. In this context, the present work evaluates response of typical X-braced, square base, 4-legged battered jacket structure using STAAD Pro. under combined vertical and lateral environmental loading. The variables included are water depth (60 m, 90 m and 120 m), wave height (5 m, 10 m and 15 m) and two foundation modelling approaches (viz., fixed at pile location and with defined pile stiffness). The connection between structure leg and pile location is modelled to simulate realistic connection. Deck loads, wind forces and current velocities are considered constant for this study. The wind and wave loads have been applied in parallel, perpendicular and diagonal directions with respect to jacket structure. The wave forces are calculated by Morrison’s equation. For obtaining pile stiffness, medium dense sand layer is considered as foundation soil. The increase in water depth and wave height results in corresponding linear increase in lateral deflection and support reactions, the effect of water depth being more prominent. Moreover, lateral and vertical deflection, shear force and bending moment in the legs, the axial forces in the lower tie beams and plan bracings, and support moments are observed to increase when pile locations are modelled with appropriate vertical, lateral and rotational stiffness instead of fixed support. The effect of water depth on member forces is higher as compared to wave height. The present work deliberates on the mechanisms/reasons to explain the observed results and contributes in direction of framing decision matrix for design optimization of jacket structures.

Modal analysis-based initial axial force recognition method for jacket platform

Jacket platform is the marine structure that anchor piles to the sea floor, among which the leg is one of the most important components of fixed marine structure. Most of the existing stress and strain monitoring methods for offshore platform ignore the existing forces in the structures caused by deck load and installation errors before the monitoring, which cannot be ignored in the subsequent monitoring and evaluation. Based on this, a method for axial force identification of marine structures is proposed in this paper. The partial differential equation of free vibration of Timoshenko beams with axial force under the influence of damping is derived. This method can accurately identify the axial force of beams without knowing the boundary conditions. The simulation results of the single beam show that this method can be used to identify the axial forces of beams with various cross sections and sizes. Then, the method is applied to the axial force identification of the legs of a four-legged jacket platform. The results show that the method can be applied to the axial force identification of the legs with the relative error (RE) of the identification results is less than 6.5%.

Selection Of Profiles In Midship Vessel Structure Operating The Regulations Of The Indonesian Classification Bureau

Ship construction generally consists of two main parts: the hull and the superstructure or deck house. Several factors must be considered in the construction of a ship. Planning the characteristics of the ship's hull, we are also planning the strength and structure of the ship itself. Midship construction is a construction that must have serious attention in calculating the ship structure. In this section, many forces are acting so that there is a relatively large risk of structural failure. One of the world's classification institutions is BKI, which provides rules for selecting structural profiles. Based on these rules, the load on ship sides is 71,284 KN/m2. Load on the ship bottom is 76,795 KN/m2, Deck Load on Deck Superstructures is 32,581 KN/m2, Load on Cargo Deck is 57,330 KN/m2, Load on Inner Bottom is 68,212 KN/m2, Load on Accommodation Decks is 3,981 KN/ m2.

Selection Of Profiles In Midship Vessel Structure Operating The Regulations Of The Indonesian Classification Bureau

Ship construction generally consists of two main parts: the hull and the superstructure or deck house. Several factors must be considered in the construction of a ship. Planning the characteristics of the ship's hull, we are also planning the strength and structure of the ship itself. Midship construction is a construction that must have serious attention in calculating the ship structure. In this section, many forces are acting so that there is a relatively large risk of structural failure. One of the world's classification institutions is BKI, which provides rules for selecting structural profiles. Based on these rules, the load on ship sides is 71,284 KN/m2. Load on the ship bottom is 76,795 KN/m2, Deck Load on Deck Superstructures is 32,581 KN/m2, Load on Cargo Deck is 57,330 KN/m2, Load on Inner Bottom is 68,212 KN/m2, Load on Accommodation Decks is 3,981 KN/ m2.

Effects of long duration earthquakes on the interaction of inertial and liquefaction-induced kinematic demands on pile-supported wharves

Nonlinear dynamic analyses were performed to evaluate the effects of ground motion duration on the dynamic response of a pile-supported wharf subjected to liquefaction-induced lateral ground deformations. The numerical model was first calibrated using recorded data from a well-instrumented centrifuge test, after which incremental dynamic analyses were conducted using a suite of spectrally matched motions with different durations. The nonlinear dynamic analyses were performed to evaluated three loading scenarios: combined effects of inertial loads from the wharf deck and kinematic loads from ground deformations, deck inertial loads only in the absence of liquefaction (with minimal kinematic loads), and kinematic loads only in the absence of deck mass inertia. The analysis results were evaluated to provide insights on the relative contribution of inertial and kinematic demands on the response of the wharf with respect to motion duration. It was found that the contribution of peak inertial and peak kinematic loads to the maximum total demand increases only slightly with motion duration and intensity. The response of the wharf was found to be primarily governed by kinematic demands when subjected to long-duration motions for the type of foundation analyzed in this study which is commonly used in the port industry.

AN OPTIMIZATION MODEL FOR PRELIMINARY STABILITY AND CONFIGURATION ANALYSES OF SEMI-SUBMERSIBLES

In the modern era of design governed by economics and efficiency, the preliminary design of a semi-submersible is critically important because in an evolutionary design environment new designs evolve from the basic preliminary designs and the basic dimensions and configurations affect almost all the parameters related to the economics and efficiency (e.g. hydrodynamic response, stability, deck load and structural steel weight of the structure, etc.). The present paper is focused on exploring an optimum design method that aims not only at optimum motion characteristics but also optimum stability, manufacturing and operational efficiency. Our proposed method determines the most preferable optimum principal dimensions of a semi-submersible that satisfies the desired requirements for motion performance and stability at the preliminary stage of design. Our proposed design approach interlinks the mathematical design model with the global optimization techniques and this paper presents the preliminary design approach, the mathematical model of optimization. Finally, a real world design example of a semi-submersible is presented to show the applicability and efficiency of the proposed design optimization model at the preliminary stage of design.

Comparison the Strength of Midship Structures With Margin Plate and Without Margin Plate

Margin plate is a part of bottom construction that joint the floor and frame construction of the ship, so the inner bottom plate will be installed cut off on the margin plate. Lately the bottom construction of the ship tends not to use the margin plate. The ship is currently built with an inner bottom plate continuously from the left side to the right side of the ship.This study aims to determine the transversal and longitudinal strength ratio of ships with and without margin plate. The analysis was carried out by using Finite Element Method so-called ANSYSTM. The result shows if the loadvariatied 0.2 x maximum load on the calculation of the transverse strength of the ship, the stress value on the ship model with a margin plate was 9.6242 (N/mm2) and on the ship model without margin plate was 8.4739 (N/mm2) under conditions 100%. The results of the comparison due to bottom load averaged 15.82%. The difference in stress due to the effect of deck loads was an average of 13.49% while the effect of side loads was on average 8.74%. The longitudinal strength of the ship was also a varied of every increase of 0.2 x maximum moment with a review point of meeting between bottom plate and bilga plate for the ship model without margin plates using the Multi Point Constraint (MPC) method looking for results in sagging conditions of 12,443 (N / mm2) and the hogging condition was -11.045 (N / mm2) at 100% x maximum moment load conditions. So that the ship model with a margin plate sagging condition was 23,189 (N / mm2) and hagging condition was -20,585 (N / mm2). The results showed the stress that occurred in the ship model without using margin plate was better to withstand the transverse and longitudinal strength of the ship compared to the ship model with the margin plate.

Nonlinear dynamic analysis of float-over deck installation for a GBS platform based on a constant parameter time domain model

Float-over deck installation has become a reliable and cost-effective method of installing heavy integrated decks for various types of offshore platforms, such as the jacket and GBS platforms. This operation involves a number of inherent complexities such as the strong nonlinear interactions between the multi-body system and environment. Therefore, dynamic modelling of the float-over system during the deck load transfer stage is a challenging task. Particularly, the wave-induced impacts among the deck, barge and platform substructure may generate strong nonlinear dynamics that cannot be accurately investigated by the current standard simulation packages. This study develops a constant parameter time domain model (CPTDM) based on Cummins equation and state-space model for analysing the nonlinear dynamics arising from the float-over deck installation of a GBS platform. Frequency domain hydrodynamic analyses of the installation barge carrying the deck with and without the presence of the GBS are both carried to identify hydrodynamic interactions. A code-to-code verification is performed to verify the accuracy and efficiency of the developed CPTDM by comparing the present results with ANSYS-AQWA. Based on the verified model, the nonlinear dynamics of the GBS platform at different load transfer stages are investigated by using Poincare maps, bifurcation diagrams and phase trajectories.

Offshore petroleum rigs/platforms: An overview of analysis, design, construction and installation

Jacket platforms are one of the most important and regularly used types of offshore structures for oil and gas extraction that have a big impact on the economy of the countries. In this paper, all aspects including design, analysis, construction and installing of the jacket type offshore structure, are summarized and classified. This type of structure is one of the specified platforms for shallow water, and for long term service, it also has the ability to carry large deck loads. This paper aims to present general guidance about the planning, design and construction of offshore jacket (template) platforms. Jacket platforms are fixed type platforms which are attached to the seabed using piles which provide stability against the wind, wave and current loads. Also, this type of offshore platform has a high initial and maintenance cost because of its exposure to corrosion, and cannot be reused after the end of its service period. Jacket platforms are most suitable for shallow water having no better alternative while it has the cost disadvantage for deep water.

An inertial macroelement for bridge abutments

In recent years, the designers of long girder bridges in seismic areas have frequently opted for a continuous deck. One implication of this choice is that in many instances bridge abutments are called upon to carry large seismic forces, engaging the dynamic response of the soil–abutment system. To deal with this problem, this paper describes the formulation of a novel one-dimensional, inertial macroelement for simulating the dynamic behaviour of bridge abutments. The non-linear force–displacement relationship is characterised by a multi-surface plasticity model using a rigorous thermodynamic approach. The plastic response of the model is bounded by the ultimate capacity of the soil–abutment system that includes dissymmetry of the soil response in active and passive loading directions, while inertial effects transferred by the near-field approach embankment are simulated through appropriate participating masses in the macroelement formulation. The paper describes a straightforward calibration procedure of the proposed macroelement for horizontal, longitudinal loading of the abutment. The macroelement has been incorporated into a simplified, global, finite-element model of a multi-span girder bridge and validated through comparisons with results from a full three-dimensional (3D) dynamic time domain analysis under seismic loading. The inertial macroelement predictions of abutment deformations, axial deck loads and pier reaction forces are in very good agreement with the 3D soil–structure interaction model, and are achieved at much lower computational costs. The proposed inertial macroelement represents a significant improvement over existing simplified models based on linear response of the soil–abutment system.

Fatigue life prediction on jacket leg structure subjected to axial and wave loads

Fixed jacket platform is an offshore structure consists of many elements such as leg and braces. Both legs and braces play an important role to support the structure from internal and external loads like structure its self and wave loads. Especially for jacket leg, the deck load is distributed to all jacket leg to support deck structure. Besides, jacket leg also resists wave loads in horizontal direction. Due to the axial load caused by deck and horizontal load caused by wave, these loads act periodically on jacket leg. Therefore, the analysis of fatigue life to jacket leg should be performed for structural design. The present study focuses on fatigue life prediction on jacket leg under axial and wave load. The numerical method is conducted to analyze fatigue life on jacket leg. It is found that the fatigue life due to axial and wave loads are 185 and 108 years, respectively.

Aeroelastic Response of Suspended Pedestrian Bridges Made of Laminated Wood and Hemp

The work described in this paper investigated, by calculating critical flutter speed, the aeroelastic response of suspended pedestrian bridges made of a laminated wood structure and hemp cables and compared them to bridges with a steel structure and harmonic steel cables. Critical flutter speed was estimated using a numerical two degree of freedom (2-DOF) generalized deck model based on finite-element modal analysis. The critical flutter speeds of two sets of 25 different structural configurations, obtained by varying the deck chord and the permanent deck loads, made of steel and of laminated wood respectively, were estimated using experimental flutter derivatives obtained from 30 wind tunnel experiments. One of the most significant results was that pedestrian bridges made of laminated wood and hemp have a higher torsional frequency than those made of steel and that this affects critical flutter speed. A case study was performed and discussed by analyzing the structural and aeroelastic response of a 250 m pedestrian bridge with a 12 m deck chord and two approximately 32 m tall towers.

Structural Modeling Using 2D Shell Element to Predict the Initial Plastic Condition of Tubular Frame Structures

A Fixed Jacket Platform is usually designed using tubular structures in which every steel pipe has a thickness and diameter. Generally, for the structural analysis of this structure, the tubular members are represented using 1D beam elements. But stress distribution, plastic strain and also ovalization around the tubular member cannot be determined by a beam element. In this research, all tubular structures were modeled using 2D shell elements to identify how the stress distribution around a tubular member is. And the non-linear analysis was carried out to identify the initial plastic condition. This study was focusing on the splash zone where this area was assumed to be exposed to the extreme wave in 8 directions according to the API RP2A-WSD code, in addition to the structure weight and deck load. Due to each direction of the wave loads, the stress distribution and initial plastic condition are studied. The modeling and non-linear static analysis in this study were done using Altair Hyperworks software.

Cable force optimization of a curved cable-stayed bridge with combined simulated annealing method and cubic B-Spline interpolation curves

Cable-stayed bridges have been extensively constructed in China in the recent two decades. This type of bridge is characterized by flexible cables that transfer the deck loads to pylons. This study focuses on the cable force optimization of a curved cable-stayed bridge based on the proposed method where simulated annealing and cubic B-Spline interpolation curves are combined for the optimization. Firstly, the numerical model of a curved cable-stayed bridge is generated in OpenSees platform. Secondly, the proposed method is elaborately described, including the establishment of cubic B-Spline interpolation curves based on four interpolation points, the flow chart of simulated annealing algorithm, objective function, design variables, and design load cases. Finally, the static responses of the bridge deck, pylons, and cables are calculated and discussed under the obtained optimum cable forces. The results reveal that the currently proposed method can efficiently generate a number of values for the objective function, and the optimum solution can be selected as the minimum of the generated objective function values. In addition, cable forces obtained by the proposed method change gradually. The proposed method for determining the optimum cable forces can be easily implemented in practice.

The ultimate strength analysis of jacket leg under deck load

Jacket platform is one of the offshore structure where the pile is fixed at the bottom sea level. Jacket leg has a significant influence on local and global structural strength under axial and lateral loads. Jacket leg is one of the most important elements for the fixed offshore structure. On the other hand, the jacket leg is also very critical to resists not only axial compression but also lateral pressure. The objective of the present study is to analyze the ultimate strength of a jacket leg under deck load. The numerical calculation is used to analyze jacket leg due to deck load. It is assumed that the support condition is fixed at bottom sea level. The result obtained by numerical analysis is therefore presented in this study. It found that the jacket leg obtained by numerical analysis can withstand the axial compression load.

Study on Transverse Strength of the Deck-Container Ships due to Laying All Containers on Deck

The strength of transversal structure of the ship has a great effect on the safety of ship. Shipswill experience conditions that affect the strength of the ships structure. A deck-container ships are the ships that all container are loaded on deck such as MV. Khendaga Nusantara series ships. The transversal strength of the ships is loaded mainly by the weight of cargolaying on deck.. This research aims to determine the transverse strength of a deck-container ship due to the all container loads on deck. The research was done by usingfinite element method throughmodeling transverse ship structure, the simulation is conducted by varying the amount and lay-out of containers on dec). The loads appliedto the model are side loads, bottomloads, and deck loads in according to BKI rules. The results shows that the stress that occurred in the web frame was 140,63 N/mm2due to the placement of the entire container on the deck(full loading). For ship structure response, a deformation of 2,86 mm occurred in the web frame area at maximum loading. Stress ratio that occurs in all ship’s structuredoes not exceed 1 in other words the working stress does not exceed the allowedstress according to BKI rules.

Analysis of Deck Slab of Reinforced Concrete Gerber-Girder Bridge Widened by Addition of Continuous Steel-Concrete Composite Girders

Many Gerber-girder bridges have become obsolete in terms of deck width and load carrying capacity. If bridge replacement is not necessary, additional girders are installed. Sometimes, due to erection convenience, the added girders do not replicate the static scheme of the refurbished structure. Such an arrangement requires special attention to preserve structural durability. An example of the inappropriate arrangement of the widening of a Reinforced Concrete Gerber-girder road bridge is presented together with an alternative concept of refurbishment based on the addition of the continuous steel-concrete girders as the outermost ones. The added deck slab connects the added and the existing parts of the structure. Attention is drawn the static analysis of the added deck slab and the influence of the added outermost girders that do not replicate the static scheme of the existing ones. Due to different static schemes of the existing and the added girders, the traditional method of the deck slab analysis is inappropriate. The Finite Element 3D model is to be applied to access bending moments in the deck slab spans correctly. It is shown that: a) the analysis of the distribution of the bending moments in the existing and the added slab spans, especially near Gerber-hinges, should be based on the Finite Element 3D modelling; b) the analysis should consider live loads acting on the whole width of the Gerber-hinge span; c) the bending moment distribution in the widened deck slab is sensitive to the distance to the Gerber hinge.