Beam Connections Research Articles

Experimental and Numerical Investigation of a Disc-Spring Damage Avoidance Device in Self-Centering Slotted Beam Connections

ABSTRACT During the past decade damage avoidance initiatives have attracted considerable attention among researchers and earthquake engineers. The paper proposes a Disc Spring Damage Avoidance Device which can practically be implemented in slotted beam connections. It comprises two distinct components for self-centering and energy dissipation. The components are tested under cyclic loading and the device performance in slotted concrete joints is validated using previous experimental and analytical results. Variation in system parameters is investigated using an improved analytical model. The results show that the device can mitigate the residual displacements down to zero while maintaining a reasonable level of energy dissipation.

Seismic performance of TFOSBs bolted endplate connection to CFSST with repaired threaded holes

This paper evaluates the seismic behavior of short thread-fixed one-sided bolts (TFOSBs) bolted connection of an I-section beam to concrete-filled square steel tube (CFSST) with repaired threaded holes by enlarging threaded holes through cyclic tests. The parameters investigated were endplate thickness, inner stiffener type, thread anchored length and bolt installation sequence. The test results are presented in terms of strength, rigidity, ductility and energy dissipation capacity. Based on the experimental results: 1) the failure modes of the connections with repaired threaded holes by enlarging threaded holes were similar to the failure modes of the connections having intact hole threads; 2) the connections with repaired threaded holes exhibited 1.8% ∼ 23.8% higher ductility and 3.9% ∼ 46.6% higher energy dissipation capacity compared with the connections having intact hole threads, and the ultimate bearing capacity of those two types of joints were comparable; and 3) the bolt installation sequence has a negligible influence on the failure modes and seismic behavior of connections with repaired threaded holes. In addition, the existing calculation methods of yield moment capacity for TFOSBs bolted endplate connections under various failure modes were still suitable for connections with repaired threaded holes, and the theoretical values and test results were well-matched with errors no greater than 15%.

Lem Beton Pengaruh Penggunan Lem Beton Pada Sambungan Pengecoran Antara Beton Lama dan Baru

In carrying out concrete work, if the casting work is not completed, then the casting must be stopped at places that do not endanger the construction according to the instructions of experts in accordance with the plan drawings. Casting of joints between old and new concrete with an overview of inclination angles of 0⁰, 45⁰, and 90⁰. Joints are part of the concrete construction to provide a safe stop for the casting for the stage of construction. The casting is carried out in several steps, in the first step filling the concrete in the cylinder mold up to half of the total, after the concrete has reached the age of 7 days, then the next concrete as connection concrete fills half of the old concrete by coating the old concrete connection using glue which is a mixture of additon addibond glue + water and without concrete only a mixture of cement + water. This research was conducted so that the implementation in the field knows the function of each slope angle at 0⁰ is used in casting column connections, 45⁰ is carried out on casting plate and beam connections, and 90⁰ is carried out on casting pile cap foundation connections. The test results of the compressive strenght & split tensile strength of concrete showed that the variation of the joint slope using glue was greater than the variation of the connection without. For the results of the greatest compressive strength test in intact concrete with an average strength value of 35,29 Mpa, while in the split tensile strength test the concrete got an average strength value of 2,37 Mpa.

Full-Scale Fatigue Tests of a New Rib-to-Floor Beam Connection for Orthotropic Steel Decks

Full-Scale Fatigue Tests of a New Rib-to-Floor Beam Connection for Orthotropic Steel Decks

Performance of the CFST column to composite beam connection under static and impact loads

A progressive collapse of structures is usually triggered by extreme incidents, especially explosions and impacts, resulting in a dynamic response that differs from the conventional column removal scenario. However, the design solutions in the criteria may not be applicable for evaluating the progressive collapse resistance of structures under the impact load. To ascertain the influence of the high strain rate effect, a finite element (FE) study is conducted on the CFST column to composite beam connection under impact and static loads. The failure modes and resistance mechanisms for two types of composite connections under the two loads are compared. Moreover, the effects of different impact energies on the impact load, vertical deflection, vertical force, and energy dissipation are discussed by varying the impact mass and velocity. Finally, the dynamic increase factors (DIFs) based on force, deflection, and energy with various impact energies are investigated. It is found that the impact load is chiefly contributed by the inertia effect (IE) at initial loading stage and by the flexural action (FA) at large deformation stage. Interestingly, the vertical force for the connection under an impact loading is negative before the approximate plastic chord rotation (θy). Although the peak impact force, maximum vertical deflection, and energy absorption ratio all increase with the impact energy raised, the former is more sensitive to impact velocity, and the latter two are more sensitive to impact mass. Moreover, a series of findings from the study demonstrate that the DIFs based on force, deflection, and energy under the impact load are significantly different from the conventional dynamic load.

Static Analysis of Sandwich Composite Panels

This paper describes the development of a sandwich composite beam based on FRP materials which is a suitable alternative to reinforced concrete beams in specific applications. These FRP materials show higher durability and stability compared to reinforced concrete in aggressive environments (e.g. wastewater treatment plants). Compared to pultruded FRP beams, the developed solution better utilizes the properties of the sub-components. The results of this research suggest that the optimum use of composite materials is when the upper and lower flanges of the beam consist of pultruded composite profiles in the TT cross-section and the standing composite grating; this creates a relatively stiff beam with a high load-bearing capacity and resistance to aggressive environments at a very low self-weight. The final properties of this beam can be adjusted thanks to the variability of the dimensions of the web as well as the variability of a suitable laminate surface treatment. This in the final combination creates a sandwich composite structure. The behaviour of the composite beam is then confirmed in this paper using a four-point bending test. Different configurations of the beam design allowed us to determine the influence of the laminate surface layer (verification of the sandwich functionality), but also the influence of the beam connection at the standing point on the resulting behaviour. The results of the experiments demonstrated the optimal physical and mechanical parameters of the sandwich composite beam structure and gave us insights for further use of this type of structure.

Seismic performance of a ring–beam connecting concrete-filled steel columns with RC frames

The seismic performance of a ring–beam connection system to integrate concrete-filled steel tubular columns and reinforced concrete (RC) frames was studied. Physical experiments on two specimens were conducted under monotonic and cyclic loading. The results showed the connection system had a displacement ductility ratio of 4.68 and an energy dissipation coefficient over 2.0. A finite-element model was established and the numerical and experimental results were compared in terms of skeleton curves and stiffness degradation trends. Parametric studies were then performed to evaluate the effects of the axial compressive force ratio, concrete strength and reinforcement ratio of the ring–beam joint (RBJ) and the reinforcement ratio of the frame beam on the seismic performance of the proposed RBJ connection system. The results showed that an increase in the axial compression ratio or strength of the concrete material improved the initial stiffness and strength of the connection system. The effects of the RBJ reinforcement ratio and the frame beam reinforcement ratio on seismic performance were negligible.

Effects of Infill Plate's Interconnection and Boundary Element Stiffness on Steel Plate Shear Walls' Seismic Performance.

Steel plate shear walls (SPSWs) are among the most desirable load-bearing systems, which have been used wildly in various structures. Recently, designers have tended to SPSWs with only beam connections showing several problems. In the present research, several SPSWs with various types of connection conditions between infill plate and boundary elements, and various stiffness of boundary elements have been studied. The result illustrates that by having the full connection between infill plate and boundary elements, at least a 33% interconnected infill plate to columns could eliminate the significant loss of fundamental factors in SPSWs connected to beam only. Furthermore, increasing the stiffness of columns has more effect on the performance of SPSWs in comparison with beams.

Numerical Study of the Behaviour of the Intermeshed Steel Connections under Cyclic loading

Abstract: Bolting and welding are the two connections which are commonly used in structural steel industry. Now the metal cutting technology has improved. Laser cutting, plasma cutting etc. are some of the new cutting technologies. Due to the evolution of these cutting technologies a new type of connection named intermeshed steel connection is introduced in structural steel industry. Bolting and welding are expensive and time-consuming operations. Easy disassembly is not possible in these types of connections. Steel is one of the best suitable materials which material reuse is possible. The introduction of intermeshed steel connection enhances easy disassembly and thereby improving material reuse. The non-linear finite element stimulations of side intermeshed steel beam to beam connection were performed using ABAQUS software. The beam flanges of the I section were connected by using dovetails and the performance of the beam flange connection is analyzed under cyclic loading.

Numerical Study of Hybrid Through Plate Connections to CFST Columns

The use of concrete-filled steel tube (CFST) columns is highly encouraged nowadays in modern multistory structures. The major reason is the extensive resistance offered by the hollow steel column to high compression. Nevertheless, further studies and data are desirable to exhaustively characterize these members and their connections to other members, such as beams. This paper investigated the behavior of concrete-filled columns connected to I-beams by through plates. Three simple types of plate connections (easy to assemble and construct) were proposed and evaluated. The behavior of these connections was examined under static loading by using advanced finite element based software (ABAQUS). The modeling techniques used in this study were validated by comparing the numerical results of a through plate connection model with the results of two relevant experimental studies. The proposed connections were classified as semi-rigid connections according to Eurocode-3. These connections were able to move the plastic hinge away from the column panel zone. The maximum plastic rotations of all connection types were greater than 40 mrad. The failure mode, and moment-rotation curves of the concrete-filled column to steel beam connections were discussed based on numerical results. The influence of through plate material and through plate thickness were evaluated via a parametrical study.

Prediction of In-plane Stiffness for the Cold-formed Steel Frame of the Wall Panel Structure

The purpose of this research was to study the lateral deformation behavior of cold-formed steel wall panel structures using experimental tests, finite element analysis and analytical methods to study the lateral stiffness of these structures. The wall panel structures were tested by full-scale experiments the experimental results of which were verified by a 3D-finite element model. The verification results showed a good correlation between the experimental tests and a finite element model. The single-column spring model was proposed for an elastic lateral stiffness analysis of the cold-formed steel wall panel structures that were formed by combinations of a guide cantilever beam and springs connection. The spring constants were defined by using the stiffness of the stub-chord connection and the bending stiffness of the chord. The experiments tests and finite element analysis were used to verify this single-column spring model. The comparison results showed good agreement between the analytical prediction, finite element analysis and experimental data in the case of the primary type of cold-formed wall structure. The proposed procedure was an efficient method for elastic lateral deformation analysis of cold-formed wall panel structures which can be used for such configurations.

Experimental study on U-Shaped steel girders using different connectors

U-shaped steel girders are a kind of structural steel that is often utilized in the construction industry. This article examines the two types of connectors used in u-shaped steel girders to determine which has the least deflection. The flexural test and compressive strength of the specimens were examined experimentally by the authors. Two u-shaped steel girders with a length of 1100mm, a span of 300mm, a depth of 100mm, a bottom plate of 75mm, and 35mm flanges each were constructed to test the endurance of two connections in this scenario. This experiment employed l-shaped angled connections and stud/shear connectors. After 28 days of curing, each specimen was tested. The effectiveness of each combination was examined in order to provide design suggestions. When compared to standard composite beams, a U-shaped steel-concrete composite girder offers stronger flexural resistance, good fire resistance, and improved sound insulation owing to the infilled concrete. However, there has been researching on the shear resistance of angle-shaped connections in U-shaped composite beams, making it difficult to determine which shear connector is best for U-shaped composite beams. According to previous studies, U-shaped composite beams with headed stud shear connections and steel angles all had an excellent flexural performance.

Mechanical performance of three types of connections used in orthogonal ribbed beams made of poplar laminated veneer lumber

This study elucidated the mechanical performance of different connections used in orthogonal ribbed beams made of poplar laminated veneer lumber (LVL). Three types of connections (namely, U-, T-, and L-shape) were fabricated and used to connect the second beam and the middle part of a main beam to form an orthogonal rib beam. A concentrated load was applied to the intersection between the main beam and the second beam. The results showed: (1) all three types of ribbed beam connection specimens showed good connecting performance and the ductile failure, including the pull-out of partial self-tapping screws, crushing of LVL at the end of the ribbed beam, and connection failure; (2) the variation of load capacity of JD2-type specimens was approximately 3.2%, which was smaller than that of the JD1- and JD3-type specimens, slightly less than 10%; (3) the ultimate bearing capacity of a connection specimen was proportional to the number of self-tapping screws; and (4) the mechanical performance of the U-shaped connection specimens was worse than that of the L-and T-shaped connection specimens. The L-shaped connection was recommended due to its better mechanical performance, simpler configuration, and more convenient fabrication.

Development and testing of demountable RC column-to-steel beam connections under cyclic loading

In order to achieve the disassembling and recycling of the structure members, three novel demountable Reinforced Concrete column to Steel beam (RCS) joints are developed in this work. By conducting the cyclic loading test and the FEM simulation, the seismic performances of three demountable RCS joints and one reference non-detachable joints are numerically and experimentally investigated. The three demountable RCS joints present larger lateral capacity and better energy absorption than the non-detachable joints. The FEM models are validated by the experimental data and can successfully predict the hysteresis responses and failure modes of the demountable RCS joints. With the help of the validated FEM model, parametric studies are conducted as well. As illustrated by the numerical result, the beam length has a marginal influence on the seismic performance of the three demountable RCS joints, while increasing the longitudinal and transverse ratios can dramatically improve the lateral capacity of the three demountable RCS joints.

Modeling stiffness of connections and non-structural elements for dynamic response of taller glulam timber frame buildings

Currently, there is limited knowledge of the dynamic response of taller glue laminated (glulam) timber buildings due to ambient vibrations. Based on previous studies, glulam frame connections, as well as non-structural elements (external timber walls and internal plasterboard partitions) can have a significant impact on the global stiffness properties, and there is a lack of knowledge in modeling and investigation of their impact on the serviceability level building dynamics. In this paper, a numerical modeling approach with the use of “connection-zones” suitable for analyzing the taller glulam timber frame buildings serviceability level response is presented. The “connection-zones” are generalized beam and shell elements, whose geometry and properties depend on the structural elements that are being connected. By introducing “connection-zones”, the stiffness in the connections can be estimated as modified stiffness with respect to the connected structural elements. This approach allows for the assessment of the impact of both glulam connection stiffness and non-structural element stiffness on the dynamic building response due to service loading. The results of ambient vibration measurements of an 18-storey glulam timber frame building, currently the tallest timber building in the world, are reported and used for validation of the developed numerical model with “connection-zones”. Based on model updating, the stiffness values for glulam connections are presented and the impact of non-structural elements is assessed. The updating procedure showed that the axial stiffness of diagonal connections is the governing parameter, while the rotational stiffness of the beam connections does not have a considerable impact on the dynamic response of the glulam frame type of building. Based on modal updating, connections exhibit a semi-rigid behavior. The impact of non-structural elements on the mode shapes of the building is observed. The obtained values can serve as a practical reference for engineers in their prediction models of taller glulam timber frame buildings serviceability level response.

Bond Behavior of Concrete-Filled Steel Tube Mega Columns with Different Connectors.

Concrete-filled steel tubes (CFSTs) are widely used in construction. To achieve composite action and take full advantage of the two materials, strain continuity at the steel–concrete interface is essential. When the concrete core and steel tube are not loaded simultaneously in regions such as beam or brace connections to the steel tubes of a CFST column, the steel–concrete bond plays a crucial role in load transfer. This study uses a validated finite-element model to investigate the bond-slip behavior between the steel tube and concrete in square CFST mega columns through a push-out analysis of eleven 1.2- × 1.2-m mega columns. The bond-slip behavior of CFST mega columns with and without mechanical connectors, including shear studs, rib plates, and connecting plates, is studied. The finite-element results indicate that the mechanical connectors substantially increased the maximum bond stress. Among the analyzed CFST mega columns, those with closely spaced shear studs and rib plate connectors with circular holes exhibited the highest bond stress, followed by plate connectors and widely spaced shear stud connectors. In the case of shear stud connectors, the stud diameter and spacing influenced the bond behavior more than the stud length. As the stud spacing decreased, the failure mode shifted from studs shearing off to outward buckling of the steel tube.

Seismic behavior of through beam connection to steel box-column

Due to its many advantages, it is highly desirable to use box columns in steel structures. However, despite the numerous advantages box columns offer, it is always difficult to implement the continuity plates inside them at the connection area. Considering this major challenge that faces the implementation of continuity plates inside the box column, researchers have always strived to find a solution either by proposing a way to remove the necessity of using continuity plates or by facilitating their implementation inside the box column. In the present research, use of through beam (TB) connections to box columns has been proposed as a possible solution. In this connection, the beam passes through the box column and the continuity plates inside the box column are removed. In addition, for better performance of the proposed connection, another connection is proposed in which two trapezoidal-shaped rib stiffener plates (TB-S1) are added to the prototype connection. To investigate the seismic behavior of these proposed connections, laboratory and numerical studies are performed on both specimens. Additionally, for better adaptation of the second specimen, TB-S1, with architectural criteria, using through curved rib stiffener plates (TB-S2) is proposed. Finally, the seismic performance of the proposed connections is examined through numerical studies. The findings reveal that there are stable hysteresis loops in the hysteresis diagrams drawn for all of the three specimens. Furthermore, based on the results, the suggested strategies are proven to be appropriate and effective for promoting the performance of the prototype.

Numerical and theoretical analysis of beam-to-column connections with ECC ring beams subjected to local compression loading

Engineered cementitious composite (ECC) is a kind of high performance cement-based composite materials with strain hardening and multiple cracking behaviour. Replacing concrete with ECC in the beam-to-column connection with ring beam may effectively improve the load-carrying capacity and ductility, as well as prevent cracks and solve durability problems caused by the brittleness of concrete. In this paper, the failure mechanism of beam-to-column connection with ECC ring beam subjected to local compression loading was investigated with the nonlinear finite element (FE) method. The results indicated that continuous lateral pressure was provided by the ECC ring beam, which improved the local compression performance of the ring beam connection. Extensive parametric studies on the local compression behavior of connections with ECC ring beams were also conducted. According to the simulation results, the peak strength of ECC connections was 13.0%–24.2% higher than that of concrete specimens. Increasing the ECC compression strength or ring beam width can effectively increase the load-carrying capacity of the connection, but the ECC tensile strain can only affect the ductility of the connection when the ultimate tensile strain was lower than 1.5%. Based on the FE analysis, an effective restraint width of the ECC ring beam was proposed, and theoretical models were established to predict the axial compressive bearing capacity of the beam-to-column connection with ECC ring beam.

Evaluation of shear behavior of PCSC shear connection for the construction of composite bridges with prefabricated decks

Conventional stud connectors are commonly used in composite bridges with prefabricated concrete decks. However, the reserved holes for grouped studs cause difficulty in the prefabrication of the concrete deck, due to tedious pouring operation during construction, which might weaken the integrity of the deck. Therefore, a precast concrete deck–steel beam–connection concrete (PCSC) connector is proposed in this study to accelerate the prefabrication and construction of a steel–concrete composite bridge. A series of static push-out tests were performed to verify the mechanical properties of the PCSC connectors. The test results indicated that the shear capacity of the PCSC connectors of the standard specimen was 12.27% higher than that of conventional clustered shear stud connectors with a diameter of 16 mm. Additionally the ultimate slip was 47.42% higher than that of the conventional stud connectors. The PCSC connector had a high capacity and ductility. The PCSC connectors had a high tolerance for precast concrete-connection concrete (PC–C) interfacial defects. Rough PC–C interfaces did slip during loading until the interface disengaging rate (i.e., the ratio of defect area to the total interface area) was less than 70%. The failure of the connector was controlled by the stud even if the slip occurred at the PC–C interface under the premise of sufficient shear connection reinforcement. A finite-element analysis was conducted to evaluate the load transfer mechanism of the PCSC connector. Finally, a comparative analysis demonstrated that the bearing capacity of the PCSC connector was accurately predicted by AASHTO LFRD.

Experimental and numerical investigation on the anti-progressive collapse performance of fabricated connection with CFST column and composite beam

The column-to-beam connection is of critical importance in the resistance of structures to progressive collapse. In previous progressive collapse tests, the concrete-filled steel tubular (CFST) column-to-composite beam connection with the ring plate experienced a high resistance and clear force transmission path. However, the ring plate and composite beam were assembled onsite. It is necessary, therefore, to further study the CFST column-to-composite beam fabricated connection. In this paper, an experimental and numerical study was carried out on the anti-progressive collapse performance of the fabricated connection with CFST column and composite beam. Three types of fabricated connections and two types of shear connectors were compared to investigate the failure mode, vertical resistance-deformation mechanism, and strain-deformation relationship. The bending moment and axial force of the steel beam as well as the contribution ratio of each component to vertical resistance were calculated and analyzed. Moreover, the nonlinear parameters of progressive collapse resistance of the specimens were compared with DoD and FEMA350 criteria. Finally, the dynamic increasing factors (DIFs) by the test, finite element (FE) model, and energy balanced (EB) method were discussed.