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1.
By using ABAQUS/Explicit, the dynamic process of an offshore wind turbine（OWT） stricken by a ship of 5000DWT in the front direction is simulated. The OWT is located on a large-scale prestressing bucket foundation constructed by an integrated installation technique. According to the simulation results, under the ship collision, a cer-tain range of plastic zone appears within a local area of arc transition structure of the bucket foundation, and the con-crete plastic zone is seriously damaged. As the stress level of OWT tower is relatively low, the OWT tower is less af-fected. A great inertial force is generated at the top of the OWT tower as the mass of nacelle and blades is up to 400 t. The displacement of the tower is in the opposite direction of the ship collision at the end of 1 s under the action of iner-tial force. There is only a minor damage in the ship bow. Most of the kinetic energy is transformed into the plastic dissipation and absorbed by the arc transition structure of bucket foundation. 相似文献
2.
《天津大学学报(英文版)》2017,(5)
The composite bucket foundation(CBF) is a new kind of foundation which has been applied in the offshore wind industry. A reasonable connection pattern between the tower and the CBF top cover is crucial for load transmissions from the superstructure. Therefore, it is essential to choose an optimum structure type for the transition section. The line type and the arc transition section models were established by ABAQUS, and the internal forces of cross section were extracted along the height direction. Specifically, the force transfer mechanism for different types of the transition sections was investigated comparatively with monotonic as well as composite loadings. The results show that the curved transition structure exhibits the better mechanical characteristics under the monotonic and composite loadings, and the reason can be illustrated that its specific arc-shape structure can effectively convert the tremendous bending moment from the turbine tower into the limited tensile and compressive stresses downwards, without the occurrence of force concentration. 相似文献
3.
In 2010,the first offshore wind turbine with integrated installation was established in Qidong sea area of Jiangsu Province,China,which led to the implementation phase of one-step-installation technique based on the design and construction of large-scale bucket-top-bearing (LSBTB) bucket foundation.The critical technique of LSBTB bucket foundation included self-floating towing,penetration with adjustment of horizontal levelness,removability and one-step-installation.The process of one-step-installation included the prefabrication of LSBTB bucket foundation in onshore construction base,installation and debugging of wind power,overall water transportation of foundation and wind power system,and installation of foundation and offshore wind turbine on the appointed sea area.The cost of one-step-installation technique was about 5 000 Yuan/kW,which was 30%-50% lower than that of the existing technique.The prefabrication of LSBTB bucket foundation took about two months.During the one-step-installation process,the installation and debugging of wind power and overall water transportation need about one to two days in sea area within 35 m depth.After the proposed technique is industrialized,the cost will be further reduced,and the installation capacity is expected to be up to 500 wind turbines per year. 相似文献
4.
Cover-bearing-type bucket foundation for offshore wind turbines has been paid more and more attention due to its low cost and great bearing capacity. In order to ensure the cover-bearing mode, the muddy soil inside the bucket foundation should be reinforced by some soil consolidation methods, such as negative pressure and electro-osmosis. Firstly, tests were conducted to obtain the reasonable current density. Meanwhile, to improve the electro-osmotic speed and effectiveness, other factors such as intermittent power and layout of electrode, were also studied in the tests. Then, the soil reinforcing tests by negative pressure combined with electro-osmosis were performed for the muddy soil consolidation inside the bucket foundation. The results showed that soil reinforcement by negative pressure was quicker and more obvious during the early phase, and electro-osmotic method can affect more range of soil by rational arrangement of electrodes. Compared with negative pressure, the electro-osmotic method was a continuous and relatively slow process of reinforcement, which was complementary to the negative pressure method. The voltage value of electro-osmosis had little effect on the muddy soil reinforcement inside the bucket foundation, and 1.5 A was chosen as the most reasonable current value for scale model testing in the electro-osmotic method. 相似文献
5.
《天津大学学报(英文版)》2015,(4)
A series of model experiments of bucket foundations concerning suction installation and negative pressure consolidation in saturated silt were carried out in a cube steel bin at Tianjin University. The experimental results show that the silt inside the bucket has been strengthened by negative pressure, and the strengthening effect decreases with the increase of the distance from the bucket. A three-dimensional numerical model of the experiments was built by means of finite element software ABAQUS with fluid-solid coupling method. The results show that the bearing capacity of the silt inside the bucket foundation increases significantly at the former stage of negative pressure consolidation, while the increasing trend slows down over time. The rotation centers of the bucket foundation and the inner soil region tend to be closer to each other based on the consolidation. The bearing capacity of the bucket foundation is improved effectively with the increase of soil strength. The effects of negative pressure consolidation on the bearing capacity of bucket foundation were also illustrated by an actual offshore wind power project case. 相似文献
6.
An integrated finite element model(FEM)of offshore wind tower-foundation-soil is established by ABAQUS, where a large-scale composite bucket foundation with seven compartments inside is applied to supporting the upper wind tower. The dynamic response of the structure-foundation system is studied under three seismic waves with the same peak ground acceleration of 0.035g. It can be seen that the dynamic response increases at the beginning with the structure height, then it decreases because the structural damping increases due to the mass effect of the upper wind turbine generator system. It is shown that the anti-liquefaction capacity of the soil inside and underneath the foundation is improved owing to the high overburden pressure of the upper structure and the constraint effect of the bucket skirt and subdivisions. Moreover, the liquefaction resistance of the soil inside the middle compartment is improved to a higher degree than that inside the side compartments. 相似文献
7.
吴继红胡阳 《福建工程学院学报》2020,(4):324-328
针对一座主梁存在裂缝的混凝土独塔斜拉桥,考虑混凝土裂缝对材料本构关系的影响,对设计荷载作用下桥梁的整体与局部响应进行分析以评估其承载能力。结果表明,在最不利的工况中,开裂后主梁顶板、底板和斜腹板、直腹板上未开裂区域的主拉应力和主压应力都小于规范给出的强度标准值;裂缝法向和切向的压应力均小于规范强度标准值,裂缝切线和法线方向的拉应力在局部很小的范围内略高于规范的抗拉强度标准值。开裂区域局部承载力有所降低,但车辆荷载作用下裂缝不会进一步扩展。 相似文献
8.
黄国凯 《福建工程学院学报》2019,(3):242-246
以某主跨85m钢管混凝土拱桥为研究对象,采用ANSYS建立局部精细化模型,对拱座进行受力分析。研究表明:拱梁组合体系拱桥拱座的结构刚度比较大,在拱脚最大弯矩工况下,最大变形出现在哑铃型拱肋加载截面下缘,变形值仅为4.3mm;拱座整体应力分析表明,结构受力以纵桥向受压为主,整体应力值不大,拱肋与拱座节点交界面因刚度突变出现了较大的应力变化,存在不大于1MPa的主拉应力;除了端横梁预应力锚固处压应力在10MPa左右,其他部位应力绝对值均在1MPa以下,满足要求;为了进一步优化结构受力,避免局部应力集中,应在结构中增加加腋、倒角等。 相似文献
9.
The large-scale bucket foundation with 30 m in diameter and 6 m in height was used as the foundation of wind turbine.The wide-shallow foundation is different from the traditional bucket foundation with... 相似文献
10.
采用有限元方法模拟了热载荷下梯度结构硬质合金的弹塑性响应．样品几何模型为二维梯度结构的轴对称圆柱体．通过引入约束因子构建了梯度材料的弹塑性本构方程．数值模拟表明：当材料温度从初始无应力的800℃下降到0℃时,在样品表面出现了压应力而在富钴区出现了拉应力;表面压应力的最大值为254MPa,富钴区拉应力的最大值为252MPa;在钴相浓度差等于或大于0．3时,钴相梯度区出现了明显的塑性流动;当温度从0℃上升到800℃时,总的塑性应变达到0．0014．塑性流动有利于降低材料内部的热应力集中． 相似文献
11.
使用全面搜索和优化处理相结合的方法,由一组余震的P波初动解资料可以推断出余震区的构造应力的主轴方向,应力主值的相对大小,并同时确定了余震的两个P波节面中的断层面。对1976年唐山地震和1966年邢台地震的余震资料的计算处理,都给出了余震区的主压应力为水平东西向,主张应力为近水平南北向的结果。因此可以认为,本方法对于用地震资料研究应力场是一个有用的工具。 相似文献
12.
《天津大学学报(英文版)》2017,(6)
The development of offshore wind farms in deep water favors floating wind turbine designs, but floating horizontal axis wind turbines are facing the challenge of high cost of energy(CoE). The development of innovative designs to reduce the CoE is thus desirable, such as floating vertical axis wind turbines(VAWTs). This study demonstrates the characteristics of aerodynamic loads and load effects of a two-bladed floating VAWT supported by a semi-submersible platform. Fully coupled simulations are performed using the time-domain aero-hydro-servo-elastic code SIMO-RIFLEX-AC. It is found that thrust, lateral force, and aerodynamic torque vary considerably and periodically with the rotor azimuth angle. However, the variation in the generator torque can be alleviated to some extent by the control strategy applied. Moreover, the variations of platform motions and tensions in the mooring lines are strongly influenced by turbulent winds, whereas those of tower-base bending moments are not. The towerbase bending moments exhibit notable two-per-revolution(2P) response characteristics. 相似文献
13.
A new type of green reactive powder concrete (GRPC) with compressive strength of 200 MPa is prepared by utilizing composite mineral admixtures, natural fine aggregates, and short and fine steel fibers. The quasi-static mechanical properties (mechanical strength, toughness, fracture energy and interfacial bonding strength) of GRPC specimens, cured in three different types of regimes, are investigated. The experimental results show that the mechanical properties of the C200 GRPC made with the powder binders that is composed of 40% of Portland cement, 25% of ultra fine slag, 25% of ultra fine fly ash and 10% of silica fume are better than the others'. The corresponding compressive strength, flexural strength and fracture energy are more than 200 MPa, and 30 000 J/ m2 respectively. The dynamic tensile behavior of the C200 GRPC is also investigated through the split Hopkinson pressure bar (SHPB) according to the spalling phenomenon. The dynamic testing results demonstrate that strain rate has an important effect on the dynamic tensile behavior of GRPC. With the increase of strain rate, its peak stress and relevant strain increase. The GRPC exhibits an excellent strain ratio stiffening effect under the dynamic tensile load with high strain ratio, resulting in a significant change of the fracture pattern. 相似文献
14.
Design of offshore wind power foundation with multi-bucket 总被引：1，自引：0，他引：1
Three- and four-bucket offshore wind power foundations with a new form of force-transferring structure are proposed in this paper, and the integrated finite element model of foundation-soil-transition structure is established by using ABAQUS. The carrying capacity of the proposed foundations is studied under vertical load, horizontal load and bending moment. It can be seen that the vertical bearing capacity of multi-bucket foundation can be roughly estimated by the vertical bearing capacity of single-bucket; the horizontal bearing capacity of the three-bucket foundation scheme is controlled by displacement, while that of the four-bucket foundation scheme is controlled by the internal forces of soils. Moreover, the carrying capacity is provided by the overall structure formed by multi-bucket before soil failure. Compared with the conventional single-bucket foundation, there are mainly tension and pressure that are applied to the multi-bucket foundation, so that the carrying capacity of the foundation can be fully utilized. The probability of soil failure can be well reduced with the proposed multi-bucket foundation, and the stress transmission of force-transferring structure is more consistent through steel beams with variable cross-section. 相似文献
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16.
Suction foundations have been deployed in the last three decades in a growing number of offshore developments, for bottom-fixed and floating structures, in shallow and deep waters, many of them successfully. Suction foundations, traditionally used as anchors and jacket foundations in the oil and gas industry, are now also used in the offshore renewable (wind) industry, e.g. for monopods, tripods, and jackets. When technically feasible, suction foundations are often cheaper than pile foundations. Additionally, their installation is relatively noise-free and, by applying overpressure, they can be removed during decommissioning. This paper focuses on the more complex design issues and some pitfalls related to suction foundation design. Additionally design practices and recommendations for suction caisson design, including installation and extraction feasibility, foundation resistance, settlements and response in sand, clay and layered soil profiles, will be presented for basic understanding. 相似文献
17.
为了保障风机的正常运行,提出基于自编码（Autoencoder,AE）的风机故障检测方法。依据法国风机ENGIE公开的风速传感器数据,建立欠完备自编码模型（UAE）、去噪自编码模型（DAE）与收缩编码器（CAE）模型,对风机风速传感器数据进行编码和解码,计算重构误差并设定阈值进行故障检测。用多风机风速传感器数据建立PCA模型并与去噪编码器模型对比。根据ROC曲线与AUC值对比,得出欠完备自编码模型、去噪自编码模型、收缩编码器模型均可用于风机异常检测,且收缩编码器效果最好的结论。PCA模型也可用于故障检测,同时多风机故障检测效果高于单一风机。 相似文献
18.
通过德州学院综合楼基础承台砼施工情况的具体分析；提出施工方法并作具体分析；根据温度、应力计算及抗裂分析，很出基础承台砼允许最高温度，为对砼的养护提供了依据；构建了温度监控措施为对政养护提供了更直观的依据。 相似文献
19.
Factors such as errors during the fabrication or construction of structural components and errors of calculation assumption or calculation methods, are very likely to cause serious deviation of many strings＇ actual prestressing forces from the designed values during tension structure construction or service period, and further to threaten the safety and reliability of the structure. Aiming at relatively large errors of the prestressing force of strings in a tension structure construction or service period, this paper proposes a new finite element method （FEM）, the ＂tensile force correction calculation method＂. Based on the measured prestressing forces of the strings, this new method applies the structure from the zero prestressing force status approach to the measured prestressing force status for the first phase, and from the measured prestressing force status approach to the designed prestressing force status for the second phase. The construction tensile force correction value for each string can be obtained by multi-iteration with FEM. Using the results of calculation, the strings＇ tensile force correction by group and in batch will be methodic, simple and accurate. This new calculation method can be applied to the prestressed correction construction simulation analysis for tension structures. 相似文献
20.
INTRODUCTION Vertical cylindrical steel tanks widely used for fluid storage generally consist of a thin bottom plate, a cylindrical shell, and a fixed or floating roof. Large tanks constructed on soft foundations are susceptible to various types of settlement deflections. The set-tlement components are: uniform settlement, planar tilt and differential settlement. The uniform settle-ment and planar tilt cause rigid-body deflection or rotation of the tank, and so, are of relatively little i… 相似文献