Transmission tower connection joint is an important connection component of the tower leg member and diagonal member. Its axial stiffness directly affects the stable bearing capacity of a transmission tower. The axial stiffness of the joint is mainly related to the connection form of joint. This paper takes the double-limb double-plate connection joint as the research object. Through the comparative study with the single-limb single-plate connection joint, the influence law of single-limb single-plate and double-limb double-plate joint on stable bearing capacity of quadrilateral transmission tower is studied from three aspects of model test, theoretical analysis and numerical simulation. Through the scale model test, it is found that the elastic stiffness of the double-limb double-plate joint is 3.12 times that of the single-limb single-plate joint, which can increase the bearing capacity of the joint by 26.1%. Through the energy method, the theoretical calculation expression of the stable bearing capacity of the quadrilateral tower considering the influence of the axial stiffness of the joint is derived. Compared with the effect of the single-limb single-plate connection joint, the double-limb double-plate joint can improve the stable bearing capacity of the quadrilateral tower by 15.6%. Considering the influence of geometric nonlinearity of tower and connecting joint, it is found that the double-limb double-plate connecting joint can improve the nonlinear stability bearing capacity of a transmission tower by 14.9%. The results show that the double-limb double-plate connection joint can not only improve the bearing capacity of the joint, but also greatly improve the stable bearing capacity of the tower. The research results can provide reference for the engineering application and design of double-limb double-plate connection joints.

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This paper addresses the problem of passive wideband localization of a shallow water noise source in nearfield with a horizontal array in the presence of multipath propagation. Multipath propagation gives rise to attenuated and time-delayed replicas of the original transmitted signal. The conventional beamforming approach to wideband localization involves the coherent signal-subspace method (CSM) via the transformation of signal subspace. In shallow water scenarios, multipath effect yields source localization bias using the conventional beamforming approach, source resolution accuracy degrades owing to the higher side lobe contributions to the beamformer output. In this paper, the steering vector is constructed in accordance with the characteristic of shallow water acoustic channel based on passive time reversal method. Cylindrical focused beamforming is used according to the shape of acoustic radiant surface. Simulation results demonstrate that source localization performance of conventional beamforming approach is improved significantly in multipath environment.