steel frames and pipe truss structures questions and answers

What are the latest progress in the research on seismic performance of steel frame structures in different seismic intensity areas?

According to the information I have searched, the following latest progress has been made in the research on the seismic performance of steel frame structures in different seismic intensity areas:

1. Application of high ductility framework :
   • In the US specification, high ductility frames (such as R=8) are recommended for high intensity zones because low intensity zones are difficult to design low ductility and high load-bearing frames to resist earthquakes. When the high-ductility frame enters a low degree of inelasticity, its seismic resistance will be significantly improved.
2. Improvements to earthquake resistance design :
   • It is proposed to adjust the “small shock” seismic force coefficient of the first and second-level seismic steel frame from 5.6 to 3.5, and reduce the height dividing line from 50 meters to 24 meters. These improvements are designed to improve the seismic resistance of steel frame structures in low intensity zones.
3. Seismic design of multi-tall buildings :
   • For a affordable housing construction project in a high-intensity area, the reaction spectrum seismic design of steel frame-steel plate wall structure and steel pipe concrete column-steel beam frame structure in the face of earthquakes was studied, and the elastic dynamic time course analysis and verification were supplemented. At the same time, the elastic-plastic seismic resistance of these two structures in rare earthquakes was compared and analyzed.
4. Impact of high-strength steel bar configuration :
   • The influence of different high-strength steel bar configurations on the seismic performance of concrete frame structures was studied. The results show that with the increase of reinforcement strength, the overall and local displacement response of the structure increased slightly, the demand for bending moment and angle ductility decreased, and the seismic resistance was improved. Especially in the 8 and 9 degrees zones, the use of HRB600 steel bars significantly improves seismic resistance.
5. Seismic resistance under rare earthquakes :
   • The seismic resistance of Class B buildings under rare earthquakes was studied, and it was found that the seismic resistance of the frame structure designed to improve seismic action was significantly better than that of the structures that only took seismic resistance measures. In addition, the seismic resistance of the structure is directly related to the ductility, and different seismic action value levels can be selected according to the different ductility. .
6. Application of multi-scale models :
   • Multi-scale model (mixed multi-dimensional model) has been widely used in the seismic performance analysis of steel frame structures. This model can effectively track the damage mechanism of local plastic instability and bearing capacity degradation of components and nodes, solving the problem that the rod system model is difficult to track local plastic instability. .
7. Application of lightweight steel structures :
   • The application of lightweight steel structures (LWS) in seismic areas has also been widely studied. Studies have shown that CFS (cold-formed steel) structures have good seismic resistance under different ambient conditions, especially in cold areas. In addition, the seismic resistance of CFS sandwich structure and CFS wooden sandwich structure has also been verified .

In the design of pipe truss structures, how to effectively control the deformation of large-span structures?

In the design of large-span tube truss structures, effectively controlling the deformation of the structure is a complex and critical issue. Here are some effective methods and techniques:

1. Reasonably arrange the measurement control network :
   • During the construction process, a measurement control network is arranged reasonably to closely monitor the installation accuracy and deformation of the components. Through computer simulation analysis, the use of the “single-machine four-point” or “double-machine four-point” method can effectively solve the problem of deformation control and closing of large-span arch trusses.
2. Segmented hoisting and high-altitude assembly :
   • The use of segmented hoisting and high-altitude assembly can reduce the difficulty and risks of on-site construction and improve construction accuracy. This method is suitable for large-span, high-difficulty pipe truss structures, such as the roofing project of Cangzhou International Convention and Exhibition Center.
3. Preheating treatment and temperature control :
   • The rods are preheated before lifting to avoid changes in stress values ​​caused by temperature changes and cracks or tensile cracks in the concrete components. Ensure that the component has sufficient hardness and strength .
4. Concrete pouring and vibration control :
   • During the concrete pouring process, the vibration and pouring quality of the concrete must be strictly controlled to ensure that the concrete is dense and free of leaks, and avoid defects such as hollows and honeycombs. After the concrete pouring is completed, timely maintenance is carried out .
5. Welding process and quality control :
   • During the construction of steel column concrete, the welding process must be strictly controlled to ensure the welding quality. Avoid air leakage or vibrating rod falling during welding to ensure that the stiffness of the welding part meets the requirements. .
6. Support system and temporary fixtures :
   • The use of support systems and temporary fixtures, such as U-shaped plates and guide blocks, can effectively improve the stability and safety of the large-span tube truss structure. These devices can provide necessary support and fixation during construction to prevent shaking.
7. BIM technology and real-time monitoring :
   • Using BIM technology to assist construction, through the control of rod production accuracy and real-time monitoring technology, the deformation of truss can be effectively predicted and controlled. During the lifting process, pay special attention to the design and positioning control of the lifting point position .
8. Construction personnel training and technical briefing :
   • Strengthen technical training for construction personnel to ensure they are aware of design requirements and relevant specifications. Scientific and rigorously formulate construction organization plans and technical briefings to ensure that all links in the construction process can be strictly implemented .

What are the application cases of high-strength lightweight steel (such as Q460) in pipe trusses and steel frames?

According to the information provided, the application cases of high-strength lightweight steel (such as Q460) in pipe trusses and steel frames mainly include the following aspects:

1. Steel pipe tower :
   • During the construction of the tower, the Q460 steel pipe tower was used for the first time. This steel pipe tower adopts a V-string barrel-shaped compact structure, which is smaller in size than the traditional V-string drum-shaped compact tower, reducing the amount of houses demolition in the line corridor. In addition, the steel pipe tower made of Q460 also has advantages in wind resistance coefficient, further reducing engineering cost and energy consumption.
2. Bridge construction :
   • Q460D steel plate is widely used in bridge construction and is used to manufacture key stress-bearing parts such as main beams, cross beams, and arch ribs. These structures can withstand high strength requirements under complex working conditions such as large spans and heavy loads, ensuring the safety and stability of the bridge.
3. High-rise buildings and large venues :
   • In the construction of high-rise buildings and large venues, Q460D steel plates are used for supporting and load-bearing components due to their high strength and lightweight properties. These structures can not only withstand the influence of large weight and natural factors, but also provide good seismic resistance.
4. Ship and Vehicle Manufacturing :
   • Q460D steel plate is also widely used in ship and vehicle manufacturing. By improving the load-bearing capacity of the hull and vehicle, the Q460D steel plate significantly improves the safety and comfort of these structures.
5. Electric power transmission tower :
   • In ultra-high voltage and ultra-high voltage transmission line towers, Q460 and Q420 steels are widely used. In response to the welding difficulties of Q460 steel, such as layered tear, cold cracks and welding defects, new welding processes and methods have been studied and formulated to ensure the requirements for steel pipe tower structure processing. .
6. Machinery manufacturing :
   • In the field of mechanical manufacturing, Q460D steel plate is used to manufacture frames and support structures of various mechanical equipment due to its excellent welding performance and processing performance. These structures not only have high strength, but also have good corrosion resistance and weldability.

What are the new developments in intelligent design tools and software tools for steel frames and pipe truss structures?

Intelligent design tools and software tools for steel frames and pipe truss structures have developed significantly in recent years, mainly reflected in the following aspects:

1. Software development based on PKPM platform :
   • In 2019, large-span space steel structure design software (STWJ) and pipe truss design software (STGHJ) were developed based on the PKPM platform. These software are based on linear calculations, solving the pain points in the design of large-span steel structures, and implementing functions such as automatic node design and construction drawing. In addition, it has innovatively realized a number of functions such as rapid modeling of complex spatial structures based on free surface modeling technology, automatic optimization of grid height, automatic arrangement of wind loads, and overall analysis of upper and lower parts.
   • In 2021, PKPM software added STWJ and STGHJ modules, adding double-layer circular flat panel mesh frames, single-layer ellipsoid mesh frames, single-layer straight curved mesh frames, single-layer hyperbolic parabolic mesh frames, and hyperbolic conical shells. Structural forms such as grid frames, as well as special structural forms such as three-center cylindrical surfaces, special spherical mesh shells, conical angle mesh shells. These new functions further improve the software’s modeling capabilities and parameterized modeling functions.
2. Application of 3D3S V10.0 software :
   • In 2018, Shanghai Tonglei Civil Engineering Technology Co., Ltd. launched 3D3S V10.0 software, focusing on the calculation, analysis and design of steel pipe truss structures. The software has been upgraded in post-processing and inter-processing functions, adding commands such as defining, querying and canceling member sequence numbers, as well as inter-processing control parameters, member unloading, generation method inter-processing data and ISO Standard inter-processing data and other functions. In addition, truss structure modeling in multiple bearing types and mixed forms is supported.
3. Feature extensions of RSTAB 9 software :
   • RSTAB 9 is a powerful structural analysis and design software suitable for beams, frames or truss structures made of steel, reinforced concrete, wood and other materials. The software supports three-dimensional calculations, which can perform linear and nonlinear analysis, quickly define structural models and calculate internal forces, deformation and bearing reaction forces. RSTAB 9 also provides functions such as wind load generation tools, automatic load combination generation, result output and report printing.
4. China Construction Steel Structure Intelligent Node Software :
   • In 2019, China Construction Steel Structure developed the TS intelligent node software for welding balls and square tubes and the TS intelligent node software for full bolt connection nodes based on the Tekla Structures software platform. These software target the problems of changing forms of complex spatial truss structures, large number of nodes and large modification workload. After the user sets the requirements, the corresponding welding balls and square tubes are automatically generated or fully bolted nodes connected to each other. These software have been successfully applied to projects such as Tar Power Station in Pakistan and Jiangxia Dahu Outdoor Activity Center.
5. Improvements to TRUSS D&E software :
   • TRUSS D&E software is a software specially designed for metal truss design. Although its design is complex and time-consuming, it automates the iterative optimization process through the creation of optimization algorithms and computing interfaces. The software develops optimization algorithms on the MATLAB platform and performs structural analysis on the ANSYS Mechanical APDL platform, which can determine the optimal positioning of node coordinates and the selection of commercially available structural profiles. .

In the optimization of seismic design, what are the latest research results of the connection nodes and damping systems of the staggered truss system?

According to existing data, the latest research results on the connection nodes and damping systems of the interlaced truss system are as follows:

1. Connecting nodes of interleaved truss system :
   • In the 11th issue of “Journal of Building Structure”, Qian Yulong and others conducted a static elastic-plastic Pushover analysis of the staggered truss-steel frame hybrid system, and found that the staggered truss part and the frame part entered the elastic one after another during the static pushover process. Plastic phase. The energy consumption capacity of the interleaved truss is limited, and the energy consumption capacity of the frame is greater than that of the interleaved truss part. The frame part after the interleaved truss yields provides subsequent lateral bearing capacity for the overall structure.
   • In addition, Qian Yulong and others also conducted experimental analysis of the connection nodes of the interlaced truss chords and found that the connection nodes between the SPD plate and the truss chords can meet the stress requirements under earthquake action. This provides a basis for perfecting the design between the SPD plate and the truss chord node.
2. Damping system for interleaved truss systems :
   • In the Journal of Building Structure, 2024, Issue 11, Zhibin Zhou et al. proposed a new type of friction energy-consuming steel truss (FED-ST), by adding friction damping with brass as the friction material to the upper chord of traditional trusses The device significantly improves the seismic resistance of the interleaved truss frame system. FED-ST specimens have good ductility and energy dissipation capacity 7.3 times higher than traditional truss specimens .
   • In his doctoral thesis, Chen Yonghui studied the seismic resistance of the multi-stage energy-consuming components introduced into the seismic truss structure. A seam steel plate damper and a double-stage yield seam steel plate damper equipped with friction pairs are proposed. These dampers have multi-stage energy dissipation characteristics and multi-stage yield behavior, which can significantly improve the seismic resistance of the staggered truss structure.

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