A semi-submersible truss type net cage culture platform integrated with wave energy device

Abstract

The application discloses a semi-submersible truss type net cage culture platform integrated with wave energy devices, which comprises a semi-submersible truss type bearing platform, a pendulum wave energy converter, an oscillating buoy wave energy converter, a deep water culture net cage system and a mooring system. The semi-submersible truss type bearing platform is coupled with the pendulum wave energy converter and the oscillating buoy wave energy converter, so that the wave energy of different wave frequencies and wave heights can be fully captured, energy efficient conversion can be realized through a matching power output system, independent guarantee can be provided for power supply of platform equipment operation, culture operation and living areas, traditional fuel power supply can be replaced, carbon emission and operation cost can be greatly reduced, and the energy requirement of deep sea long-term culture can be met.

Description

Technical Field

[0001] This invention relates to the field of marine renewable energy utilization and deep-sea cage aquaculture technology, and in particular to a semi-submersible truss cage aquaculture platform integrating wave energy device. Background Technology

[0002] Deep-sea aquaculture is a core approach to alleviating pressure on nearshore aquaculture resources and meeting the growing global demand for aquatic products. Wave energy, as a marine renewable energy source with abundant reserves, high energy density, wide distribution, and good predictability, is an ideal solution for on-site energy supply to deep-sea aquaculture platforms. Integrating wave energy converters with deep-sea cage aquaculture platforms to achieve coordinated operation of wave energy development and aquaculture has become a key research direction for the development of the marine blue economy.

[0003] Currently, the research and application of wave energy-aquaculture integrated platforms both domestically and internationally still face numerous technical bottlenecks, making it difficult to meet the needs of deep-sea engineering applications. Energy supply and wave energy utilization efficiency are low. Traditional aquaculture platforms rely on fossil fuels or shore power transmission, which has problems such as high transportation costs, environmental pollution, and unstable power supply in the open ocean. Existing aquaculture platforms with integrated wave energy converters mostly use a single type of wave energy conversion device and do not consider the actual energy loss of the power output system. The energy conversion model deviates greatly from the actual engineering situation, resulting in low wave energy capture efficiency.

[0004] The hydrodynamic coupling effect has not been quantified. Most studies only analyze the hydrodynamic performance of wave energy converters or aquaculture platforms in isolation, without systematically quantifying the interaction mechanism between the aquaculture platform and the wave energy converter in the coupled system. This makes it impossible to optimize the motion characteristics of the wave energy converter through the coupling effect, resulting in poor stability of wave energy capture.

[0005] The stability of aquaculture platforms and cages is insufficient. Traditional floating aquaculture platforms have weak resistance to wind and waves, and unreasonable mooring system design can easily lead to platform displacement and swaying; aquaculture cages lack rigid support, and in severe sea conditions, the netting is prone to wrinkling and damage, resulting in a high risk of escape of cultured organisms.

[0006] The platform has low functional integration. Existing platforms mostly focus on wave energy power generation or aquaculture, without achieving integrated functions such as energy management, water quality monitoring, aquaculture operation and maintenance, and personnel living. As a result, the utilization efficiency of marine resources and platform space is low, and the overall development benefits are poor.

[0007] Therefore, developing an integrated platform that combines dual-type wave energy converters with efficient wave energy utilization and stable deep-sea aquaculture is key to solving the above-mentioned technical problems. Summary of the Invention

[0008] The purpose of this invention is to provide a semi-submersible truss-type cage aquaculture platform integrating wave energy devices to solve the problems existing in the prior art.

[0009] To achieve the above objectives, the present invention provides the following solution: The present invention provides a semi-submersible truss-type cage aquaculture platform integrating wave energy device, including a semi-submersible truss-type bearing platform, a pendulum wave energy converter, an oscillating float-type wave energy converter, a deep-water aquaculture cage system, and a mooring system; Both the pendulum wave energy converter and the oscillating float wave energy converter are fixedly installed on the semi-submersible truss-type support platform, forming a coupled integrated structure with the semi-submersible truss-type support platform. Each of them is equipped with a power output system adapted to its own motion form. The deep-water aquaculture cage system is suspended and fixed below the semi-submersible truss-type support platform, forming a closed three-dimensional aquaculture space; One end of the mooring system is fixedly connected to a semi-submersible truss-type support platform, and the other end is used to fix it to the seabed anchor. The semi-submersible truss-type bearing platform is a truss structure welded from marine-grade high-strength steel. The platform integrates equipment area, living area and aquaculture operation area. The longitudinal initial stability height of the platform is not less than 1.8m and the lateral initial stability height is not less than 1.5m.

[0010] According to the semi-submersible truss-type cage aquaculture platform with integrated wave energy device provided by the present invention, the oscillating float-type wave energy converter includes two steel structure forms, and each of the two steel structure forms is provided with a hydraulically driven power output system. The two steel structure forms capture wave energy through rotational motion around the y-axis.

[0011] According to the semi-submersible truss-type cage aquaculture platform with integrated wave energy device provided by the present invention, the oscillating float-type wave energy converter is an aluminum alloy structure pendulum plate, and the aluminum alloy structure pendulum plate is hinged to the side of the semi-submersible truss-type bearing platform. It captures wave energy by vertical oscillating motion along the z-axis. The grid size of the aluminum alloy structure pendulum plate is 0.8×0.8m.

[0012] According to the semi-submersible truss-type net cage aquaculture platform with integrated wave energy device provided by the present invention, the deep-water aquaculture net cage system includes a net, tethering ropes, and net counterweights; the net is made of ultra-high molecular weight polyethylene material, and the net is suspended and fixed below the aquaculture operation area of ​​the semi-submersible truss-type support platform by tethering ropes, and the edge of the net is fixedly connected to the tethering ropes by stainless steel buckles to form a closed three-dimensional aquaculture space; the net counterweights are precast concrete blocks, and the net counterweights are evenly fixed to the bottom edge of the net to maintain the vertical unfolding shape of the net.

[0013] According to the semi-submersible truss-type cage aquaculture platform with integrated wave energy device provided by the present invention, the mooring system adopts eight rigid galvanized steel cables; one end of the rigid galvanized steel cable is fixedly connected to the corresponding mooring point of the semi-submersible truss-type support platform, and the other end of the rigid galvanized steel cable is used to be fixedly connected to the seabed gravity anchor; tension sensors are configured on the rigid galvanized steel cables, and the tension sensors are signal-connected to the control unit of the equipment area of ​​the semi-submersible truss-type support platform for real-time monitoring of the tension data of the rigid galvanized steel cables.

[0014] According to the semi-submersible truss-type cage aquaculture platform with integrated wave energy device provided by the present invention, the equipment area of ​​the semi-submersible truss-type bearing platform is integrated with a water quality monitoring device, an energy management device, a mooring status detection device, and a remote communication and control unit; the signal output terminal of the water quality monitoring device is connected to the signal input terminal of the remote communication and control unit, and the signal output terminal of the mooring status detection device is connected to the signal input terminal of the remote communication and control unit; the energy management device is electrically connected to the power output system of the pendulum wave energy converter, and the energy management device is electrically connected to the power output system of the oscillating float wave energy converter, for the control, conversion, and storage of electrical energy.

[0015] According to the semi-submersible truss-type cage aquaculture platform with integrated wave energy device provided by the present invention, the aquaculture operation area of ​​the semi-submersible truss-type support platform is equipped with a feeder and a crane. The discharge end of the feeder is set in accordance with the aquaculture space of the deep-water aquaculture cage system to achieve precise feeding during the aquaculture process. The crane is fixedly connected to the semi-submersible truss-type support platform and is used for lifting, maintaining and harvesting aquaculture cages.

[0016] The semi-submersible truss-type cage aquaculture platform with integrated wave energy device provided by the present invention has a total mass of 1.2 × 10⁻⁶ for one group of the steel structures. 5 kg, moment of inertia 1.8 × 10 6 kg·m 2 The total mass of the other group of steel structures is 1.5 × 10⁻⁶. 5 kg, moment of inertia 2.1 × 10⁻⁶ 6 kg·m 2 .

[0017] The present invention discloses the following technical effects: The device integrates two types of wave energy converters: pendulum and oscillating float. Coupled with the carrier platform, it can fully capture wave energy of different frequencies and heights. Through the matching power output system, it achieves efficient energy conversion, providing independent power supply for platform equipment operation, aquaculture operations, and living areas. It replaces traditional fuel power supply, significantly reduces carbon emissions and operating costs, and is suitable for the energy needs of long-term deep-sea aquaculture.

[0018] The semi-submersible truss-type support platform is welded with marine-grade high-strength steel, making it structurally stable and highly resistant to wind, waves, and sinking. Deep-sea aquaculture cages are suspended below the platform, forming a closed, three-dimensional aquaculture space. This not only isolates the platform from pollutants and predatory organisms from the open sea but also ensures water circulation, improving the aquaculture environment. At the same time, the mooring system is fixed and reliable, effectively resisting extreme marine environments, reducing aquaculture risks, and ensuring the survival rate of aquaculture organisms.

[0019] The platform integrates equipment, living, and aquaculture operation areas, achieving integrated aquaculture, energy supply, and operational support, significantly improving aquaculture efficiency and reducing manual maintenance costs. Its truss structure design balances load-bearing capacity and flexibility, adapting to various deep-sea conditions. It meets the needs of large-scale deep-sea aquaculture while expanding wave energy utilization scenarios, promoting the synergistic development of marine aquaculture and new energy industries. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of the semi-submersible truss-type cage aquaculture platform integrating wave energy device according to the present invention. Figure I ; Figure 2 This is a schematic diagram of the structure of the semi-submersible truss-type cage aquaculture platform integrating wave energy device according to the present invention. Figure II ; Figure 3 This is a schematic diagram of the structure of the semi-submersible truss-type cage aquaculture platform integrating wave energy device according to the present invention. Figure III ; Figure 4 This is a schematic diagram of the structure of the semi-submersible truss-type cage aquaculture platform integrating wave energy device according to the present invention. Figure IV .

[0022] Among them, 1. Semi-submersible truss-type bearing platform; 2. Pendulum wave energy converter; 3. Oscillating float wave energy converter; 4. Deep-water aquaculture cage system; 5. Mooring system. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] Reference Figures 1-4 The present invention provides a semi-submersible truss-type cage aquaculture platform integrating wave energy device, including a semi-submersible truss-type bearing platform 1, a pendulum wave energy converter 2, an oscillating float wave energy converter 3, a deep-water aquaculture cage system 4, and a mooring system 5; Both the pendulum wave energy converter 2 and the oscillating float wave energy converter 3 are fixedly installed on the semi-submersible truss-type support platform 1, forming a coupled integrated structure with the semi-submersible truss-type support platform 1. Each of them is equipped with a power output system adapted to its own motion form. The deep-water aquaculture cage system 4 is suspended and fixed below the semi-submersible truss-type support platform 1, forming a closed three-dimensional aquaculture space; One end of the mooring system 5 is fixedly connected to the semi-submersible truss-type support platform 1, and the other end is used to fix it to the seabed anchor. Among them, the semi-submersible truss-type bearing platform 1 is a truss structure welded from marine-grade high-strength steel. The platform integrates equipment area, living area and aquaculture operation area. The longitudinal initial stability height of the platform is not less than 1.8m and the lateral initial stability height is not less than 1.5m.

[0026] In operation, the mooring system 5 securely anchors the semi-submersible truss-type support platform 1 to the seabed, providing a stable working foundation for the entire system. Under the continuous action of ocean waves, the pendulum wave energy converter 2 rotates with the waves to capture wave energy, while the oscillating float wave energy converter 3 oscillates vertically with the waves to capture wave energy. The two wave energy converters form a coupled integrated structure with the support platform, optimizing the wave energy capture effect by relying on the platform's constrained motion and synchronous excitation effect. The power output systems of both converters accurately convert rotational mechanical energy and translational mechanical energy into stable electrical energy, continuously supplying power to the monitoring and control equipment in the platform equipment area, the living support facilities in the living area, and the aquaculture operation and maintenance equipment in the aquaculture operation area. The system achieves energy self-sufficiency for the platform. The deep-sea aquaculture cage system 4 is suspended and fixed below the supporting platform. Relying on the platform's longitudinal initial stability of not less than 1.8m and lateral initial stability of not less than 1.5m, it always maintains a closed three-dimensional aquaculture form and safely carries out deep-sea aquaculture operations. The equipment area collects operational data such as sea water quality, platform attitude, and mooring tension in real time. The aquaculture operation area completes precise feeding, cage lifting and maintenance, and fish harvesting. The entire device simultaneously completes the entire process of wave energy development, power conversion, and deep-sea aquaculture. It can maintain stable operation under different sea conditions, completely solving the problems of energy supply and aquaculture stability of deep-sea aquaculture platforms, and realizing the integrated and coordinated operation of wave energy utilization and aquaculture.

[0027] Further optimization of the scheme: the oscillating float wave energy converter 3 includes two steel structure forms, and each of the two steel structure forms is equipped with a hydraulically driven power output system. The two steel structure forms capture wave energy through rotational motion around the y-axis.

[0028] The oscillating float-type wave energy converter 3 employs two steel structure configurations, both designed to capture wave energy through rotation around the y-axis. When ocean waves act on either steel structure, the wave's undulations propel the structure in a reciprocating rotation around the y-axis, converting the wave's kinetic and potential energy into the steel structure's mechanical rotational energy. The hydraulically driven power output systems on each steel structure convert this rotational mechanical energy into hydraulic energy, which is then further converted into electrical energy by the hydraulic system's energy conversion components. This provides power to various platform equipment, achieving efficient wave energy capture and conversion.

[0029] Further optimization of the scheme: the oscillating float wave energy converter 3 is an aluminum alloy structure pendulum plate, and the aluminum alloy structure pendulum plate is hinged to the side of the semi-submersible truss type bearing platform 1. It captures wave energy by vertical oscillating motion along the z-axis. The grid size of the aluminum alloy structure pendulum plate is 0.8×0.8m.

[0030] The oscillating float-type wave energy converter 3 uses an aluminum alloy structure pendulum plate, which is hinged to the side of the semi-submersible truss-type support platform 1. Its core captures wave energy through vertical oscillation along the z-axis. When waves impact the aluminum alloy pendulum plate, the plate, under the combined action of the wave's thrust and buoyancy, performs a vertical reciprocating oscillation along the z-axis around the hinge, transferring the mechanical energy of the vertical oscillation to the matching power output system, thus converting wave energy into electrical energy, adapting to wave scenarios with different wave heights.

[0031] Further optimizing the scheme, the deep-water aquaculture cage system 4 includes a net, tethering ropes, and net counterweights. The net is made of ultra-high molecular weight polyethylene material. The net is suspended and fixed below the aquaculture operation area of ​​the semi-submersible truss-type support platform 1 by tethering ropes. The edges of the net are fixedly connected to the tethering ropes by stainless steel buckles to form a closed three-dimensional aquaculture space. The net counterweights are precast concrete blocks, which are evenly fixed to the bottom edge of the net to maintain the vertical unfolding shape of the net.

[0032] The deep-sea aquaculture cage system consists of a net, tethering ropes, and net counterweights. Its core function is to achieve the stable construction of a closed, three-dimensional aquaculture space and ensure a suitable aquaculture environment. The net is made of ultra-high molecular weight polyethylene, which is corrosion-resistant and tensile-resistant. It is suspended below the aquaculture area on the platform by tethering ropes. The edges of the net are secured to the tethering ropes with stainless steel clips, ensuring a firm connection and good sealing, forming a closed aquaculture space. The counterweights, made of precast concrete blocks evenly fixed to the bottom edge of the net, use their own weight to stretch the net, maintaining its vertically unfolded shape and preventing deformation or tangling due to water flow. This also ensures the effective volume of the aquaculture space without affecting natural water circulation, providing a suitable environment for the cultured organisms.

[0033] The front end of the mesh counterweight is designed with a wedge shape.

[0034] Further optimization of the scheme: the mooring system 5 adopts eight rigid galvanized steel cables; one end of the rigid galvanized steel cable is fixedly connected to the corresponding mooring point of the semi-submersible truss-type support platform 1, and the other end of the rigid galvanized steel cable is used to be fixedly connected to the seabed gravity anchor; tension sensors are installed on the rigid galvanized steel cables, and the tension sensors are connected to the control unit of the equipment area of ​​the semi-submersible truss-type support platform 1 for real-time monitoring of the tension data of the rigid galvanized steel cables.

[0035] Further optimizing the scheme, the equipment area of ​​the semi-submersible truss-type bearing platform 1 is integrated with a water quality monitoring device, an energy management device, a mooring status detection device, and a remote communication and control unit; the signal output end of the water quality monitoring device is connected to the signal input end of the remote communication and control unit, and the signal output end of the mooring status detection device is connected to the signal input end of the remote communication and control unit; the energy management device is electrically connected to the power output system of the pendulum wave energy converter 2, and the energy management device is electrically connected to the power output system of the oscillating float wave energy converter 3, for the management, conversion, and storage of electrical energy.

[0036] Eight rigid galvanized steel cables are evenly distributed, with one end fixed to the corresponding mooring point of the platform and the other end connected to a gravity anchor on the seabed. The weight of the gravity anchor and the friction of the seabed are used to firmly fix the platform in the designated aquaculture area, resisting the impact of wind, waves and ocean currents on the platform and preventing platform displacement. Tension sensors installed on the steel cables collect tension data in real time and transmit the signals to the control unit in the platform equipment area. The control unit analyzes the tension data and monitors the stress state of the steel cables in real time. If abnormal tension occurs (such as overload or slack), it can issue an early warning in time to ensure the safe and stable operation of the mooring system.

[0037] Further optimization of the scheme: the aquaculture operation area of ​​the semi-submersible truss-type support platform 1 is equipped with a feeder and a crane. The discharge end of the feeder corresponds to the aquaculture space of the deep-water aquaculture cage system 4, which is used to achieve precise feeding during the aquaculture process. The crane is fixedly connected to the semi-submersible truss-type support platform 1 and is used for lifting, maintaining and harvesting aquaculture cages.

[0038] The water quality monitoring device collects water quality parameters such as water temperature, pH, and dissolved oxygen in the aquaculture area in real time and transmits the signals to the remote communication and control unit. The mooring status detection device simultaneously collects the operating parameters of the mooring system 5 and feeds them back to the control unit to achieve real-time monitoring of water quality and mooring status. The energy management device is electrically connected to the power output systems of the two wave energy converters to manage, convert, and store the converted electrical energy and rationally allocate it to various equipment on the platform to ensure a stable energy supply. The remote communication and control unit can realize remote transmission of monitoring data and remote control of equipment, improving the platform's operation and maintenance efficiency.

[0039] The scheme was further optimized, with one group of steel structures having a total mass of 1.2 × 10⁻⁶. 5 kg, moment of inertia 1.8 × 10 6 kg·m 2 The total mass of the other steel structure is 1.5 × 10⁻⁶. 5 kg, moment of inertia 2.1 × 10⁻⁶ 6 kg·m 2 .

[0040] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0041] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A semi-submersible truss-type cage aquaculture platform integrating wave energy device, characterized in that, Includes a semi-submersible truss-type support platform (1), a pendulum wave energy converter (2), an oscillating float wave energy converter (3), a deep-sea aquaculture cage system (4), and a mooring system (5); The pendulum wave energy converter (2) and the oscillating float wave energy converter (3) are both fixedly installed on the semi-submersible truss-type bearing platform (1) and form a coupled integrated structure with the semi-submersible truss-type bearing platform (1). The two are respectively equipped with a power output system adapted to their own motion form. The deep-water aquaculture cage system (4) is suspended and fixed below the semi-submersible truss-type support platform (1) to form a closed three-dimensional aquaculture space; One end of the mooring system (5) is fixedly connected to the semi-submersible truss-type bearing platform (1), and the other end is used to fix it to the seabed anchor. The semi-submersible truss-type bearing platform (1) is a truss structure welded from marine-grade high-strength steel. The platform integrates equipment area, living area and aquaculture operation area. The longitudinal initial stability height of the platform is not less than 1.8m and the lateral initial stability height is not less than 1.5m.

2. The semi-submersible truss-type cage aquaculture platform integrating wave energy device according to claim 1, characterized in that, The oscillating float wave energy converter (3) includes two steel structure forms, and each of the two steel structure forms is equipped with a hydraulically driven power output system. The two steel structure forms capture wave energy through rotational motion around the y-axis.

3. The semi-submersible truss-type cage aquaculture platform integrating wave energy device according to claim 1, characterized in that, The oscillating float wave energy converter (3) is an aluminum alloy structure plate, and the aluminum alloy structure plate is hinged to the side of the semi-submersible truss type bearing platform (1) by a hinge. It captures wave energy by vertical oscillating motion along the z-axis. The grid size of the aluminum alloy structure plate is 0.8×0.8m.

4. The semi-submersible truss-type cage aquaculture platform integrating wave energy device according to claim 1, characterized in that, The deep-water aquaculture cage system (4) includes a net, a tethering rope, and a net weight. The net is made of ultra-high molecular weight polyethylene material. The net is suspended and fixed below the aquaculture operation area of ​​the semi-submersible truss-type support platform (1) by the tethering rope. The edge of the net is fixedly connected to the tethering rope by stainless steel buckles to form a closed three-dimensional aquaculture space. The net weight is a precast concrete block. The net weight is evenly fixed at the bottom edge of the net to maintain the vertical unfolding shape of the net.

5. A semi-submersible truss-type cage aquaculture platform integrating wave energy device according to claim 1, characterized in that, The mooring system (5) uses eight rigid galvanized steel cables; one end of the rigid galvanized steel cable is fixedly connected to the corresponding mooring point of the semi-submersible truss-type bearing platform (1), and the other end of the rigid galvanized steel cable is fixedly connected to the seabed gravity anchor; a tension sensor is configured on the rigid galvanized steel cable, and the tension sensor is signal-connected to the control unit of the equipment area of ​​the semi-submersible truss-type bearing platform (1) for real-time monitoring of the tension data of the rigid galvanized steel cable.

6. A semi-submersible truss-type cage aquaculture platform integrating wave energy device according to claim 1, characterized in that, The equipment area of ​​the semi-submersible truss-type bearing platform (1) integrates a water quality monitoring device, an energy management device, a mooring status detection device, and a remote communication and control unit; the signal output end of the water quality monitoring device is connected to the signal input end of the remote communication and control unit, and the signal output end of the mooring status detection device is connected to the signal input end of the remote communication and control unit; the energy management device is electrically connected to the power output system of the pendulum wave energy converter (2), and the energy management device is electrically connected to the power output system of the oscillating float wave energy converter (3), for the control, conversion, and storage of electrical energy.

7. A semi-submersible truss-type cage aquaculture platform integrating wave energy device according to claim 1, characterized in that, The semi-submersible truss-type support platform (1) is equipped with a feeder and a crane in the aquaculture operation area. The feeder's discharge end corresponds to the aquaculture space of the deep-water aquaculture cage system (4) to achieve precise feeding during the aquaculture process. The crane is fixedly connected to the semi-submersible truss-type support platform (1) and is used for lifting, maintaining, and harvesting aquaculture cages.

8. A semi-submersible truss-type cage aquaculture platform integrating wave energy device according to claim 2, characterized in that, The total mass of one of the steel structure types is 1.2 × 10⁻⁶. 5 kg, moment of inertia 1.8 × 10 6 kg·m 2 The total mass of the other group of steel structures is 1.5 × 10⁻⁶. 5 kg, moment of inertia 2.1 × 10⁻⁶ 6 kg·m 2 .

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