Influence of Double-Limb Double-Plate Connection on Stable Bearing Capacity of Quadrilateral Transmission Tower

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.

Research on seismic performance of prefabricated concrete-filled steel tubular frame joints

PurposeConcrete-filled steel tube structures are widely used for their high bearing capacity, good plasticity, good fire resistance and optimal seismic performance. In order to give full play to the advantages of concrete-filled steel tube, this paper proposes a prefabricated concrete-filled steel tube frame joint.Design/methodology/approachThe concrete-filled steel tube column and beam are connected by high-strength bolted end-plate, and the steel bars in the concrete beam are welded vertically with the end-plates through the enlarged pier head. In addition, the finite element software ABAQUS is used numerically to study the seismic performance of the structure.FindingsThe ductility coefficient of the joint is in 1.72–6.82, and greater than 2.26 as a whole. The equivalent viscous damping coefficient of the joint is 0.13–3.03, indicating that the structure has good energy dissipation capacity.Originality/valueThe structure is convenient for construction and overcomes the shortcomings of the previous on-site welding and on-site concrete pouring. The high-strength bolted end-plate connection can effectively transfer the load, and each component can give play to its material characteristics.

Instrumentation Results of New Manual for Assessing Safety Hardware Crash Tested Barriers for William P. Lane, Jr. Bridge

Two new bridge barriers were crash tested in accordance with AASHTO Manual for Assessing Safety Hardware (MASH) guidelines for future use on the William P. Lane Bridge over the Chesapeake Bay: (1) a combination barrier consisting of a reinforced concrete parapet with a top steel rail evaluated for Test Level 4 (TL-4); and (2) a combination barrier consisting of a steel parapet with a top steel rail evaluated for test levels TL-4 and TL-5. For the first test configuration, the reinforced concrete barrier was attached to a representative overhang deck slab using anchor rods. In the vicinity of the vehicle impact points, load cells were installed to measure forces in anchor bolts, and strain gauges were attached to reinforcing bars to resolve measured strain data into forces through the overhang deck slab. In the second test configuration, the steel barrier was supported by evenly spaced representative floorbeams using a bolted base plate connection. Strain gauges were attached to elements of the barrier at support locations adjacent to the vehicle impact point to evaluate force transfer through the barrier system into the base plate connections. Linear potentiometers were installed to measure lateral dynamic deflection of the barrier near the vehicle impact region. This paper presents the analysis results of the force, strain, and displacement data measured in the barrier and deck structural components during crash load testing.

Test and Finite Element Analysis of a New Type of Double-Limb Double-Plate Connection Joint in Narrow Base Tower

The connection between the leg members and diagonal members of the urban transmission line tower is mostly in the form of single-limb connection. This paper puts forward a new connection form of pipe double-limb double-plate connection joint, which is based on the model of key joints in an urban narrow base tower structure. The traditional pipe single-limb single-plate and new pipe double-limb double-plate joint are analyzed and studied from three aspects of theory, numerical simulation and experimental study. Through finite element analysis, it is obtained that the section stress of angle steel under eccentric load is 2.05 times of that under axial load, which is basically consistent with the 2.5 times of the theoretical calculation. This shows that the stress of the angle steel in the pipe double-limb double-plate joint is greatly reduced as the axial stress component, which can ensure the safety of the angle steel. Based on the theoretical analysis of the tensile force of two kinds of joints, through the test research and corresponding numerical simulation of pipe single-limb single-plate and pipe double-limb double-plate joints, under the same load, compared with pipe single-limb single-plate joints, the pipe double-limb double-plate joints designed in this paper can greatly reduce the stress of connection plates and members, and compared with the existing joint forms, the bending stress of joint plates can be reduced by about four times, which greatly improves the bearing capacity of the joint. The research on the pipe double-limb double-plate connection joint will provide the basis for the design of new connection joints of narrow base towers in urban areas.