Perforated Steel Plate Research Articles

The effects of brick walls strengthened with perforated steel plates on frame behavior

Some bays of reinforced concrete (RC) buildings are mostly infilled with brick walls according to architectural demands. The brick infill walls are generally not considered load-bearing members, but they are known to increase the strength and stiffness of the structure under seismic loads. However, this contribution can be provided at rather low story drifts, since brick is a quite brittle construction material. The present study aimed at improving the seismic performance of structure by strengthening the infill walls of the RC frame with perforated steel plates which is quite ductile. A total of 14 half-scale test specimens, including two references (an RC frame and an RC frame with infill wall) and 12 strengthened specimens, were tested under reversed cyclic lateral loading. Strengthened specimens exhibited ductile behavior and no significant loss in strength observed up to 7.5% drift ratio. In addition to the attained ductile behavior, increases in the strength reaching two times the reference value were obtained. Hence, this easily-applicable method, which can be applied without too much disturbance to the residents, is claimed to have the potential to be used for strengthening numerous RC structures in the future.

Nonlinear seismic performance of code designed perforated steel plate shear walls

Nonlinear seismic performances of code designed Perforated Steel Plate Shear Walls (P-SPSW) were studied. Three multi-storey (4-, 8-, and 12-storey) P-SPSWs were designed according to Canadian seismic provisions and their performance was evaluated using time history analysis for ground motions compatible with Vancouver response spectrum. The selected code designed P-SPSWs exhibited excellent seismic performance with high ductility and strength. The current code equation was found to provide a good estimation of the shear strength of the perforated infill plate, especially when the infill plate is yielded. The applicability of the strip model, originally proposed for solid infill plate, was also evaluated for P-SPSW and two different strip models were studied. It was observed that the strip model with strip widths equal to center to center diagonal distance between each perforation line could reasonably predict the inelastic behavior of unstiffened P-SPSWs. The strip model slightly underestimated the initial stiffness; however, the ultimate strength was predicted well. Furthermore, applicability of simple shear-flexure beam model for determination of fundamental periods of P-SPSWs was studied.

Perforated shear + reinforcement bar connectors in a timber-concrete composite solution. Analytical and numerical approach

This paper presents a study of a novel shear connector in a timber-concrete composite solution, focussing on the determination of an analytical expression that makes it possible to predict its behaviour and a numerical analysis that describes it accurately. The shear connector is composed of a perforated steel plate inserted into a slot within the timber rib and glued, in combination with reinforcing corrugated steel bars affixed to the top of the plate. Previous tests made it possible to establish failure mode in different T composite section plate-rebar configurations. These results determine the effectiveness of the system in terms of force-slip behaviour, with systematic failure in the timber section. A simple predictive model is proposed to determine the ultimate capacity of the joint, taking into account the mechanical properties of timber in relation with the fracture plane and the timber-adhesive interface. This model makes it possible to apply a design process that is able to predict the stiffness of the connection.FEM models were analysed for each configuration in a variable load process equal to that used in the test, according to the standard procedure. A variable friction coefficient in contact definition made it possible to achieve an accurate descriptive model in association with the test procedure.

Experimental analysis of glued-in steel plates used as shear connectors in Timber-Concrete-Composites

This paper describes experimental research into timber-concrete composite (TCC) connections made with discrete perforated steel plates glued in timber with epoxy adhesive. Continuous steel meshes have proven to be very strong and rigid elements in TCC structural members. This paper studies the strength and stiffness of these connectors when used in a discrete way, alone and in combination with reinforcing bars. Six types of connector were subjected to experimental tests, analysing two connection lengths and three configuration systems of the connector elements (in which bars are added longitudinally or transversally). The experimental results show that the connections made with discrete steel meshes are very strong and rigid, and that it is possible to design them for ductile failure. Comparison of the results for plates of different lengths indicates that failure occurs in the longest connections in the wood at lower average shear stresses. No significant behavioural differences were detected between connectors made only of plate and those that were reinforced with additional bars. The high slip moduli values indicate that it would be possible to design structural elements with a composite action close to 100% using this type of connection.

Underwater acoustic ground cloak development and demonstration

Acoustic ground cloaks, which conceal an object on a rigid surface, utilize a linear coordinate transformation to map the flat surface to a triangular void by compressing space into two triangular cloaking regions consisting of a homogeneous anisotropic acoustic metamaterial. Transformation acoustics allows for the realization of a coordinate transformation through a reinterpretation of the scale factors as a new material in the original coordinate system. An underwater acoustic ground cloak was constructed from perforated steel plates and experimentally tested to conceal an object on a pressure release surface. The perforated plate acoustic ground cloak successfully cloaked the scattered object. There was excellent agreement between the phase of the surface reflection and cloak reflection with a small amplitude difference. Above 15 [kHz], the cloaking performance decreased as the effective material parameters of the perforated plate metamaterial deviated from the required material parameters.

High-capacity hold-down for mass-timber buildings

Engineered mass-timber products such as cross-laminated timber enable the use of timber as structural material in tall buildings. One of the advantages of using timber is the reduction in weight and the resulting reduction in foundation costs. A lower structural mass, however, will also lead to less inherent resistance to overturning forces caused by lateral loads such as wind. This paper summarizes the experimental studies on a novel high-capacity hold-down solution for tall timber structures. The connection assembly consists of a modified Holz-Stahl-Komposit (HSK)™ application: perforated steel plates that are adhesively bonded into the timber panel with duct tape being used to cover some rows of the holes in the perforated plate. This arrangement allows the perforated steel plate to yield inside the timber which prevents lateral buckling of the hold-down. A total of 54 tests at material, component and full-scale hold-down level were conducted using quasi-static monotonic and reversed cyclic loading. The results demonstrated that the modified HSK hold-down assembly provides high initial stiffness as well as the required capacity and ductility for seismic applications in tall mass-timber buildings.

Experimental investigation on the bearing mechanism of Perfobond rib shear connectors

The bearing capacity of Perfobond rib shear connectors (PBL shear connectors) mainly comes from adhesion, interfacial frictional force, dowel actions, and end bearing force. However, the contribution of each component to the total bearing capacity has not been deeply addressed. An experimental study on 18 PBL shear connectors deeply embedded in massive reinforced concrete was performed to determine the bearing mechanism. The strain distributions were sophisticatedly measured by the optical fibers on the perforate steel plate and passing rebar. Results showed that key design parameters such as diameter of the holes in the perforated steel plate, diameter of passing rebar and the transverse reinforcement ratio influenced the bearing capacity. A formula was proposed for estimating the bearing capacity of PBL shear connectors, which quantifies the portions of shear-friction force and the dowel action of the passing rebar. Comparisons between the analytical solution and test results validated the proposed formula. With this validated formula, further dissection of the bearing mechanism of PBL shear connectors was carried out.

Numerical study of the elasto-plastic buckling in perforated thin steel plates using the constructal design method

Numerical study of the elasto-plastic buckling in perforated thin steel plates using the constructal design method

Topology optimization of steel plate shear walls in the moment frames

In this paper, topology optimization (TO) is applied to find a new configuration for the perforated steel plate shear wall (PSPSW) based on the maximization of reaction forces as the objective function. An infill steel plate is introduced based on an experimental model for TO. The TO is conducted using the sensitivity analysis, the method of moving asymptotes and SIMP method. TO is done using a nonlinear analysis (geometry and material) considering the buckling. The final area of the optimized plate is equal to 50% of the infill plate. Three plate thicknesses and three length-to-height ratios are defined and their effects are investigated in the TO. It indicates the plate thickness has no significant impact on the optimization results. The nonlinear behavior of optimized plates under cyclic loading is studied and the strength, energy and fracture tendency of them are investigated. Also, four steel plates including infill plate, a plate with a central circle and two types of the multi-circle plate are introduced with equal plate volume for comparing with the results of the optimized plate.

Shear capacity of a novel joint between corrugated steel web and concrete lower slab

Composite girder with corrugated steel web is one of the promising concrete-steel hybrid structures with superior properties and cost effectiveness widely applied in highway and railway bridges. The connection between concrete slabs and corrugated steel web is an important part of such composite structure. In order to improve pouring quality and durability of concrete for joint structure between corrugated steel webs and concrete lower slab, the validity of placing lower slab on the inner side of corrugated steel webs was confirmed and a new joint structure with perforated plate connectors was proposed. Push-out tests on proposed joint structure with different parameters including the welding width and the plate thickness were carried out to study their shear strength, shear stiffness, failure modes and relative slip characteristics. Subsequently, three-dimensional finite element models taking material non-linearity and nonlinear contact between steel and concrete interface into consideration were built and validated by the push-out tests. Afterwards, parametric studies were performed to further investigate the influences of geometrical parameters (such as width, height and thickness of perforated steel plate) and material parameters including steel yielding strength and concrete compressive strength on ultimate shear strength and failure mode of the joint structure. Analytical results indicate that the shear loading capacity is increased with the thickness, the width and height of perforated plate, and the compressive strength of concrete. However, steel yielding strength, presence or absence of perforating rebar, have a negligible effect on ultimate shear strength of the joint structure. Finally, prediction equations of shear capacity were provided and compared with experimental and numerical results. The calculated shear capacity agrees well with experimental and numerical ones, indicating provided analytical equations can accurately predict shear capacity for such novel joint structure.

Seismic strengthening of infill walls with perforated steel plates

Brick infill walls are mostly used in reinforced concrete (RC) structures. It is a known fact that the use of these walls inside RC frames composed of columns and beams improves the strength and stiffness of the structure under seismic loadings. Since the brick wall is a rather brittle material, it only improves the strength for a small lateral drift range and this contribution is frequently neglected in the design process. In this work, the aim is to strengthen existing infill walls using perforated steel plates and so to improve the seismic performance. Totally 13 specimens, one being a reference and the remaining 12 strengthened, were manufactured and tested under reversed cyclic loading. The results showed that the strengthened specimens were extremely ductile and no significant loss in strength was observed up to 10% drift ratio. In addition to this ductile behavior, an increase of strength up to twice the reference value was observed. It is concluded that in the near future, by using this easy to apply technique, most RC structures with brick infill walls can be strengthened against earthquakes without discomforting the people within the structure, or at least more safety can be provided.

08.02: Experimental research of multiple perfobond connectors for composite girders

ABSTRACTExtensive research has been carried out in recent years focusing on the behaviour of innovative connectors for steel and concrete composite girders. Those elements exhibit large resistance and adequate behaviour under different load types, and at the same time are easy to fabricate and to erect on site. Among these types, the Perfobond connector or Perfobond rib, consisting of a perforated steel plate welded to the steel beam flange, has been extensively studied by numerous authors, due to its particularly convenient efficiency, behaviour and ductility characteristics.Although many connector types have been studied in the past, few studies focused on the behaviour of groups of special connectors, a typical arrangement used in conventional headed stud connectors.This paper focuses on the behaviour of multiple Perfobond connectors placed side‐by‐side on a steel girder and immersed in the reinforced concrete slab. This quite innovative arrangement enhances the resistance from a single connector classic layout, but the proximity to other connectors may significantly change the behaviour of individual connectors that interact with each other.Fourteen push‐out tests on groups of Perfobond connectors were carried out at the Civil Engineering Department of the University of Coimbra, Portugal, while this paper reports and discuss the results.The investigated variables were: the number of connectors, ranging from one (the basic arrangement) to three; the spacing between connectors; the transverse reinforcement within the connector's holes; and the concrete strength. The results are presented and discussed concentrating on the connector's structural response for shear transfer capacity, ductility and collapse modes. A comparative assessment of these properties focusing on the number of connectors and its spacing is presented and discussed, aiming at establishing preliminary conclusions about the behaviour of Perfobond groups. In addition, a brief comparison of the experimental results with existing analytical models for Perfobond connectors is also presented to establish the most convenient model for this particular geometry. Finally, some adapted models referred in the literature to cope with Perfobond groups are applied to the tested geometries and the analytical and experimental tests are compared and discussed.

Experimental studies on perforated plate girders with inclined stiffeners

Ultimate load behaviour of perforated steel plate girders with inclined stiffeners is presented in this paper. A series of experimental tests on ten simply supported girders were tested to failure under shear load applied at the centre of gravity of the section. Centrally located circular web openings of various diameters were introduced at the middle panels of the girders. Effects of different inclination angles of intermediate stiffeners on the post-buckling behaviour are the main focus of the present study. Five different angles, viz., 90°, 75°, 60°, 45° and 30°, measured from the bottom flange, were accounted for in the tests. Considerable variations of strength, failure characteristic, and load-deflection response may be observed due to effects of such inclinations. Test results show significant increases in the ultimate strength to the extent of 92% as the angle of inclined stiffeners reduced. Non-linear finite element analyses were also carried out to provide additional support for the test results. A reasonably close agreement between the two sets of results establishes the accuracy of the numerical analysis.

Hysteretic behavior of perforated steel plate shear walls with beam-only connected infill plates

The steel plate shear wall with beam-only connected infill plate (SSW-BO) is an innovative lateral load resisting system consisting of infill plates connected to surrounding beams and separated from the main columns. In this research, the effects of perforation diameter as well as slenderness ratios of infill plates on the hysteresis behavior of SSW-BO systems were studied experimentally. Experimental testing is performed on eight one-sixth scaled one-story SSW-BO specimens with two plate thicknesses and four different circular opening ratios at the center of the panels under fully reversed cyclic quasi-static loading in compliance with the SAC test protocol. Strength, stiffness, ductility and energy absorption were evaluated based on the hysteresis loops. It is found that the systems exhibited stable hysteretic behavior during testing until significant damage in the connection of infill plates to surrounding beams at large drifts. It is also seen that pinching occurred in the hysteresis loops, since the hinge type connections were used as boundaries at four corners of surrounding frames. The strength and initial stiffness degradation of the perforated specimens containing opening ratio of 0.36 compared to the solid one is in the range of 20% to 30% and 40% to 50%, respectively.

Investigation Effect of Type, Property and Dimension of Stiffener Perforated Steel Shear Wall

Steel plate shear wall (SPSW) according extra ductility and high strength and lateral stiffness and improved behavior in plastic stage recognized as a good lateral system for building structure, particularly as it interests with earthquake resistant design. Improvise of opening is one advantage of this system. The researchers on perforated steel plate shear wall have shown that the shear strength and stiffness of an un-stiffened steel shear wall decrease due to perforation of the infill plate. So stiffener leads to increasing stability of structural system of buckling and strength, lateral stiffness. To this research still plate shear wall with opening that can be of different material such as rebar, steel plate also effect of increase and decrease of steel plate section area and effect of its dimension studied. Analysis result was observed that applying steel plate with similar area, leads to more ultimate strength. In additionally ultimate strength increase when area increased. With comparing of result of stiffeners dimension due maximum ultimate shear strength. Finally suggest optimum aspect ratio (b/t).

The Out-of-Plane Bending Behavior of Brick Infill Walls Strengthened with Perforated Steel Plates

The brick infill walls cease to contribute to the lateral strength and stiffness of a structure as soon as they fail in a brittle manner in the early stages of an earthquake. Recent studies indicated that the perforated steel plates externally bonded to both faces of a wall lead to two benefits. First, the increase in the lateral strengths and rigidities of the walls increase the overall lateral strength and stiffness of the structure. Secondly, the increase in the ductilities of the walls allows the walls to absorb higher amounts of the earthquake-induced energy before failure so that smaller amounts of energy are required to be absorbed by the bearing structural members. The present study is dedicated to investigate the efficiency of this technique on the behavior of brick walls under out-of-plane bending moments, induced by the blast effect of an explosion or pressure from the soil, wind or snow next to the wall. A brick wall strengthened with perforated steel plates and a brick wall strengthened with perforated steel plates and steel strips on both faces were subjected to four-point bending. The steel plates greatly contributed to the bending capacities of the walls. The use of steel strips on the plates did not affect the flexural capacity of the wall, while increasing the ductility of the wall considerably.

SHEAR STRENGTH OF PERFORATED PLATE GIRDERS WITH INCLINED STIFFENERS

A series of experimental tests on perforated steel plate girders with inclined stiffeners is presented herein. Ten simply supported girders of practical size were tested for failure under a single concentrated load applied at the center of gravity of the section. Circular web openings of various diameters were introduced at the middle panels of the girders. Effects of different inclination angles of intermediate stiffeners on the ultimate load behavior are the main focus of the present study. Five different angles, measured from the bottom flange, were considered in the tests, viz., 90°, 75°, 60°, 45°, and 30°. Variations of strength, failure characteristic, and load-deflection response have been observed. The ultimate strength was found to increase considerably from 21% to 92% as the angle of inclined stiffeners reduced from 90° to 30°.

Theoretical and Experimental Studies of the Internal Force Transfer Mechanism of Perfobond Rib Shear Connector Group

Abstract Perfobond rib shear connector (PBL) is capable of transferring large internal force between steel and concrete components. It has been widely used in composite bridges as a key load-transferring component. In this paper, the load-transfer mechanism of the PBL shear connector group is investigated theoretically and experimentally. An analytical model was developed based on load-slip characteristics of a single shear connector and load-deformation compatibility of a perforated steel plate and concrete component. The model was validated through full-scale connection loading experiments. Test results indicate that the applied load is unevenly distributed to multiple layers of PBL shear connectors in a connector group in the elastic stage, and the load becomes more evenly distributed as plastic deformation of the connectors takes place. The presented analytical model provides an efficient way for analyzing and designing a PBL shear connector group. The analytical results indicate that increasing the n...

Biomimetic-inspired CFRP to perforated steel joints

In many high-performance applications there is a need to join steel to CFRP parts. However the stiffness mismatch between these materials leads to high stress concentrations in such joints. This paper uses the biomimetics approach to help develop solutions to this problem. Nature has found many ingenious ways of joining dissimilar materials, with a transitional zone of stiffness at the insertion site commonly used. In engineering joints, one way to reduce the material stiffness mismatch is to gradually decrease the effective stiffness of the steel part of the joint by perforating it with holes. This paper investigates joining of flat perforated steel plates to a CFRP part by a co-infusion resin transfer moulding process. The possible effect of mechanical interlocking as resin fills the perforations is assessed by filling the holes with PTFE prior to moulding to prevent such resin ingress. The joints are tested under static tensile loading. The perforated steel joints show a 175% increase of joint strength comparing to non-perforated joints. Finite element analyses are used to interpret the experimental results. It has been found that the model is able to reproduce with accuracy the experimental load–displacement test curves and show the failure mechanisms of the joint.

Anisotropic acoustic metafluid for underwater operation.

The paper presents a method to design and characterize mechanically robust solid acoustic metamaterials suitable for operation in dense fluids such as water. These structures, also called metafluids, behave acoustically as inertial fluids characterized by anisotropic mass densities and isotropic bulk modulus. The method is illustrated through the design and experimental characterization of a metafluid consisting of perforated steel plates held together by rubber coated magnetic spacers. The spacers are very effective at reducing the effective shear modulus of the structure, and therefore effective at minimizing the ensuing coupling between the shear and pressure waves inside the solid effective medium. Inertial anisotropy together with fluid-like acoustic behavior are key properties that bring transformation acoustics in dense fluids closer to reality.