STUDY OF MECHANICAL PROPERTIES OF A NOVEL COLUMN-BEAM-COLUMN PREFABRICATED STEEL FRAME JOINT

This study examined the cyclic behavior of glass-fiber-reinforced polymer composite column-beam connectors in various diameters. Mean learning (XGBoost and the random forest algorithm) and numerical methods were used to identify the data collected experimentally due to the rotation behavior. The initial sample had a column length of 1200 mm and a cross-section of 80 × 80 mm, with a beam section measuring 80 × 160 mm. The second sample had a 100 × 100 mm column and a beam section measuring 100 × 200 and 1200 mm, respectively. For the third sample, the column’s dimensions were 130 × 130 mm in cross-section and 1200 mm in length, and the beam was 130 × 260 mm. Spruce wood is used to make glulam components for columns and beams. Following the creation of the column-beam connections, glass-based fiber-reinforces polymer (FRP) fabric was used to wrap the column-beam connections that needed strengthening. The cyclic behavior of the reinforced reference samples and the samples with reinforced column-beam joint areas was examined. The column-beam connection with code C13B13-R has the most load-carrying capacity (13.9 kN), while the beam with code C08B08-UR has the lowest load-carrying capacity (03.4 kN). Examining the table reveals that the findings of the numerical analysis and the experiment provide comparable conclusions. When comparing experimental and numerical results, similar values are found for stiffness values (R 2 of 0.99), load-bearing capacity (R 2 of 0.99), and energy consumption capacity (R 2 of 0.99). With R 2 of 0.9978, RMSE of 0.01017, and MAE of 0.01043, the random forest approach identified the stiffness values in the model with the best accuracy. It has been shown that the seismic behavior of column-beam couplings built with these materials may be studied with mean learning models and numerical analysis, instead of demanding and time-consuming experimental studies.

The problems of the existing methods for the determination of combining and technologically interlinked construction processes and activities are considered under the modern construction conditions of various facilities. The necessity to identify common parameters that characterize the interaction nature of all the technology-related construction and installation processes and activities is shown. The research of the technologies of construction and installation processes for buildings and structures with the goal of determining a common parameter for evaluating the relationship between technologically interconnected processes and construction works are conducted. The result of this research was to identify the quantitative evaluation of interaction construction and installation processes and activities in a minimum technologically necessary volume of the previous process allowing one to plan and organize the execution of a subsequent technologically interconnected process. The quantitative evaluation is used as the basis for the calculation of the optimum range of the combination of processes and activities. The calculation method is based on the use of the graph theory. The authors applied a generic characterization parameter to reveal the technological links between construction and installation processes, and the proposed technique has adaptive properties which are key for wide use in organizational decisions forming. The article provides a written practical significance of the developed technique.

To prevent brittle damage and improve the post-earthquake rapid repair capability of beam-column connections, a precast reduced beam section (PRBS) connection joint that can be rapidly repaired under earthquake action was proposed in this study. Four specimens, including a repaired specimen, were subjected to a quasi-static test to investigate the seismic performance and repair ability of the connection. Seismic performance indices such as the failure mode, hysteresis curve, skeleton curve, strain distribution, and ductility were obtained through observations and analyses. The results indicated that the novel connection exhibited superior load-bearing, energy dissipation, and rotation capacities, compared to the welded flange-bolted web and traditional bone-weakened connections. This novel connection effectively relocated the plastic hinge to alter the failure mode and prevent brittle damage. Additionally, rapid post-earthquake repair was achieved by replacing the dog-bone-style splice section, maintaining a high load-bearing capacity and seismic performance. Finite element (FE) models were established to analyze the mechanical behavior of the specimens, and a parametric analysis was conducted to study the influence of different parameters on the load-bearing capacity of the connection. Based on the experimental and FE analysis results, the possible yield and failure modes of the connection were analyzed, and a calculation method for the bearing capacity of the PRBS connection was proposed. A comparative result demonstrates that the proposed calculation method can accurately predict the load-carrying capacity of a connection.

Numerical study on compressive behavior of a 3D-printed sand mold-cast S-CN connector

To eliminate the geometrical defects and to reduce the damage caused by out-off-plane rotation of the end portion of the conven-tional buckling restrained braces, as well as introducing a new way to facilitate the construction and installation process, the exper-imental behavior of 5 proposed specimens as new type of all-steel tubular buckling restrained braces (AST-BRB) under cyclic axial loads was studied.The proposed specimens consist of a steel tube as a load bearing member (core), which is placed inside a larger tube as a buckling restraining member (pod). At the two ends of the core member, different end details and connection (compared to the common BRBs) are provided as the elastic transitional region. The performance of the specimens were evaluated based on indices, such as damage mode, repeatable behavior, adjusted strength factors, load-bearing capacity, and cumulative inelastic displacement.The evaluation of the results indicated that, the specimens, which welded variable cross-section steel lids at both ends of the core, have superior seismic performance. The superior specimens, for all cycles with larger displacements of the yielding displacement, exhibited a stable hysteresis behavior in bearing of cyclic loads. The bearing pressure was about 1.07 times greater than the tensile load. The cumulative inelastic axial displacements of these specimens is at least 209 times of their yield displacement. Meanwhile, they can tolerate at least 140 % compressive load and 10 % greater tension loads relative to the nominal capacity of the core individual.

Verification on both load-bearing and plastic deformation capacity for a steel beam-column welded connection at elevated temperature is of importance to secure fire safety of steel building structures. At the fire resistant design, it is required that the beam-column welded connection does not fracture before the adjacent heated steel beam exhibits stable plastic collapse mechanism. The AIJ design recommendation (Architectural Institute of Japan, 2017) cannot, however, offer a fire resistant verification method for the beam-column welded connection, because the fire resistance has not been verified experimentally. Main purpose of this study is to clarify both load-bearing and deformation capacity for steel beams including the beam-column welded connections at high temperature, by conducting their experiments under a condition on constant temperature and gradually increasing load. The beam-column welded connection with through diagrams is arranged in the center of beam specimen. The boundary condition is simple support and a shear force is applied through the medium of the column above the beam-column welded connection. In the welded connection, scallop working for a web plate in the wide flange section is not used. This kind non-scallop working is widely used for the actual beam-column welded connections to avoid brittle fracture at the structural design in Japan. The base metal and weld material are JIS SN490B and JIS YGW11, respectively. Stiffener plates to avoid local buckling of the flange plate in the beam are arranged near the beam-column welded connection, because the large tensile force is acted to the welded connection. The number of specimens is five and an experimental parameter is specimen temperature, which is given by ambient temperature, 600, 700, 800 and 900 °C. The specimen temperature was gradually risen by an electric furnace, and the shear force was applied after the temperature reached to the test temperature and kept constant it. Bending moment and rotation angle of the specimen are estimated respectively, and the shear force loading continued until the rotation angle exceeded 0.2. From minute investigations on the experimental results, the following knowledge was obtained. All specimens exhibited the beam bending collapse mode and the welded connections did not fracture. They possessed the larger bending strength than the full plastic moment at each temperature. The shear force applied at the high temperature experiments approximately kept constant with the specimen plastic deflection increase. From specimen observation after those experiments, the weld metal itself in the beam-column connection besides the beam largely deformed, however, ductile cracks in the weld metal and heat affected zone were not observed. It is expected that the beam-column welded connection with the high seismic performance by the non-scallop working also possesses the high load-bearing and deformation capacity at the fire. Furthermore, in-plane numerical analyses using a beam element were conducted, and it was clarified that both numerical and experimental specimen behaviors approximately agreed.

Strength and behavior of axially and eccentrically loaded built-up closed sections using four cold-formed steel open sections

Aim: Damages to buildings as a result of earthquakes in our country and in the world; structural design can consist of concepts such as rigidity and ductility, as well as column-beam junction details. Column-beam connections of structures with a steel frame carrier system can be designed as a rigid connection where the moment is transferred by using bolts or welding connection tools, or as an articulated connection. In the literature and in practice, the column-beam junction detail in the bearing system can be made using two methods called modular and conventional methods. Method: In the study; the behavior of the column-beam connection under the effect of displacement-controlled load of the two-stories frame system constructed using a modular and conventional method was investigated using the Abaqus finite element program. Findings: The load-displacement values obtained from the finite element model, the stress distribution and the yield state in the joint area were compared according to the 100 mm vertical and 100 mm horizontal displacement-controlled loading condition of the bearing system created by using different methods. Conclusion: The developed modular frame system exhibited the strong column-weak beam principle, which is the desired system behavior according to the earthquake resistant building design principle. However, although the frame system created using the traditional method is more rigid and the load bearing capacity is higher than the modular frame system.

Development of a monolithic-like precast beam-column moment connection: Experimental and analytical investigation

Effectiveness of masonry infill walls on steel frames with different beam-column connections under progressive collapse

Experimental investigation of the rotational behaviour of glulam column-beam joints reinforced with fiber reinforced polymer composites

This paper presents an experimental study on a full-scale two-storey, two-bay by one-bay steel-concrete composite slim floor that was subjected to horizontal pseudo-dynamic and cyclic pseudo-static loadings. The primary objective of this test is to investigate the bearing behavior and load bearing capacity of the composite slim floor under horizontal loads. The time-history load-displacement curves, hysteretic curves, skeleton curves, structural deformation and the failure mode were obtained from the tests. The test results indicated good load bearing capacity and good ductility of the test structure and also required improvement of the construction of the beam-column connection. At the end of this paper, some suggestion on the improvement of composite beam-column connection has been proposed.

In this study, a novel prefabricated light-steel beam–column connection consisting of a thin-walled rectangular hollow section column and two cold-formed steel truss beams is proposed and investigated by carrying out experimental tests. Eight cruciform beam–column connection specimens with different configurations are fabricated and tested to failure under monotonic static loading. First, failure mode and the loading–displacement curve of each specimen are investigated. Consequently, the effect of three variables, including truss-beam configuration, truss-beam type, and with or without sleeve tube reinforcing the column, on the static bearing capacity of the proposed connection and the deflection of the truss beams are investigated. It is found that plug welding the sleeve to the column can significantly increase the static bearing capacity of the proposed connection. In addition, fillet welding connecting the column and the channel connectors to accommodate the end of the truss beams is crucial to the static bearing capacity of the proposed beam–column connection. Because beam–column connections with single-truss beams have a higher load-bearing capacity and require less material and assembly work, it is recommended to adopt this type of configuration for the proposed connection.

The use of fiber optic sensors for the internal state measurements of large civil structures has been increasing in recent years. Sensors are embedded into the reinforced concrete structure in order to obtain information about the internal structural health and overall structural performance. The installation process is of utmost importance for if incorrectly done, the sensors will not withstand the rigorous conditions present during the construction and concrete pouring process. A detailed description of the sensor installation and excavation process undertaken when a suite of fiber optic sensors were embedded into a 67 m long steel truss bridge spanning the Winooski River in Waterbury, Vermont (USA) arise is presented.

The use of fiber optic sensors for the internal state measurements of large civil structures has been increasing in recent years. Sensors are embedded into the reinforced concrete structure in order to obtain information about the internal structural health and overall structural performance. The installation process is of utmost importance for if incorrectly done, the sensors will not withstand the rigorous conditions present during the construction and concrete pouring process. A detailed description of the sensor installation and excavation process undertaken when a suite of fiber optic sensors were embedded into a 67 m long steel truss bridge spanning the Winooski River in Waterbury, Vermont (USA) arise is presented.