Single-story Steel Frames Research Articles

Theoretical and experimental study on vibration control of a tuned liquid inerter damper with additional damping net and sloped-bottom

In order to overcome the deficiencies of large water consumption and insufficient damping performance of the traditional tuned liquid damper (TLD), a novel tuned liquid inerter damper by combining a rack and pinion inerter device with a damping net and sloped-bottom tuned liquid damper (DNS-TLD) which is named as damping net and sloped-bottom tuned liquid inerter damper (DNS-TLID) is proposed. The damping mechanism of DNS-TLID is analyzed and the solution formula about fundamental frequency is derived, then a mechanical model of the DNS-TLID-single-degree-of-freedom (SDOF) structural system is established. A functional solution method for estimating equivalent liquid motion velocity is presented, and a simplified calculation method of the total equivalent damping ratio of DNS-TLID is proposed. The accuracy of the proposed mechanical model and the calculation formula for the total equivalent damping ratio is verified through the shaking table tests of one single-story steel frame structure. The results from both theoretical analysis and experimental investigation demonstrate that DNS-TLID can effectively achieve lightweight vibration control and significantly enhance the damping performance of structures subjected to ground motions. Compared to other types of TLDs, DNS-TLID can effectively integrate the advantages of DNS-TLD and the rack and pinion inerter device and exhibit superior performance and lightweight control effects. Thus, as a novel advanced combination damper, DNS-TLID proves to be highly applicable in engineering applications.

Performance of steel-plate shear wall at high temperature

Purpose The high heat induced by fire can substantially decrease the load-bearing capacity, which is more critical in unprotected steel structures than concrete reinforced structures. One of the conventional steel structures is a steel-plate shear wall (SPSW) in which thin infill steel plates are used to resist against the lateral loads. Due to the small thickness of infill plates, high heat seems to dramatically influence the lateral load-bearing capacity of this type of structures. Therefore, this study aims to provide an investigation into the performance of SPSW with reduced beam section at high temperature. Design/methodology/approach In the present paper, to examine the seismic performance of SPSW at high temperature, 48 single-span single-story steel frames equipped with steel plates with the thicknesses of 2.64 mm, 5 mm and 7 mm and yield stresses of 85 MPa, 165 MPa, 256 MPa and 300 MPa were numerically modeled. Furthermore, their behavioral indices, namely, strength, stiffness, ductility and hysteresis behavior, were studied at the temperatures of 20, 458, 642 and 917? The simulated models in the present paper are based on the experimental specimen presented by Vian and Bruneau (2004). Findings The obtained results revealed that the high heat harshly diminishes the seismic performance of SPSW so that the lateral strength is reduced even by 95% at substantially high temperatures. Therefore, SPSW starts losing its strength and stiffness at high temperature such that it completely loses its capacity of strength, stiffness and energy dissipation at the temperature of 917? Moreover, it was proved that by separating the percentage of their participations variations of the infill plate in SPSW, their behavior and the bare frame can be examined even at high temperatures. Originality/value To the best of the authors’ knowledge, the seismic performance of SPSW at different temperatures has not been evaluated and compared yet.

Life safety in single-story steel frame buildings, Part II - probabilistic design

PurposeThis paper aims to investigate the probability of unacceptable consequences from structural fire damage in a typical Scandinavian single-story steel frame building and discusses it in relation to life safety. This paper is a complement to the paper “Life safety in single-story steel frame buildings, Part I – deterministic design” by Sandström (2019) which considers the same design philosophy but with a probabilistic design approach.Design/methodology/approachThe reliability of a single-story steel frame building is investigated by using crude Monte Carlo simulation by including consideration to the fire conditions.FindingsThe investigated building does not meet the safety levels as stipulated by EN 1990 for structural fire damage. However, by including consideration to the fire conditions in the compartment, it is shown that the life safety objective is not compromised by the structural fire damage, i.e. the structure remains intact as long as any individuals/firefighters can survive within the fire area compartment.Originality/valueThis paper presents practical application of a conceptual paper presenting a general approach to structural fire safety design and the life safety objective.

Inelastic static and dynamic seismic response assessment of frames with stochastic properties

The article studies the inelastic seismic response assessment of structures with spatially varying material properties via the stochastic finite element method. This is a problem with a complex response function due to stochastic variability and material nonlinearity. Existing formulations either assume linear-elastic behaviour, or use dense models in order to capture both stochasticity and inelasticity. This results to models that require excessive computational resources. The article shows that for material nonlinear problems, the stochastic variability can be taken into consideration using flexibility-based models which allow performing repeated time-history simulations within a reasonable computational time, without loss of accuracy. The interpolation can be adjusted through a user-defined parameter, thus avoiding the need for a dense FE mesh. Contrary to past research, the modelling proposed has many applications in structural engineering, since it allows nonlinear, static or dynamic, simulations of real-scale frame structures with stochastic properties. The proposed method is demonstrated in the framework of the spectral representation method combined with Monte Carlo simulations, but it can be combined with any other method for the description of the stochastic field. A generic single-storey steel frame and a six-storey reinforced concrete frame are considered in order to demonstrate the efficiency of the proposed modelling.

Research of mechanical model of particle damper with friction effect and its experimental verification

Particle damping (PD) technology has a remarkable effect in reducing vibration and noise for high frequency vibration such as mechanical analysis and aviation, and has been widely applied in some engineering practices. However, in the field of low frequency and low amplitude vibration control for building structures, the research and application of particle damper technology is still in the preliminary stage. The deficiencies and problems mainly include the mechanical model of PD is not perfect enough and the mechanism of vibration reduction is not clear enough. In the light of the shortcomings of the existing theoretical model of the PD, a mechanical model of the PD with friction effect between the particle and the structure is proposed, and the analytical solution of the displacement response for the mechanical model subjected to harmonic excitation is obtained. The model can fully represent the collision and non-collision process of PD, and the phase trajectories can embody the complex nonlinear characteristics of PD. The theoretical and motion characteristics of the PD are verified by the electromagnetic shaking table test of a single-story steel frame with PD, which proves the rationality of the theoretical model and the correctness of the analytical results, as well as the necessity of considering the friction effect. The parameters of mass ratio, excitation amplitude, excitation frequency and motion gap are further analyzed, so the mechanism of vibration reduction is clearer. Finally, compared with the traditional model of impact damper, it is obvious that the mechanical model of PD with friction effect can more reasonably evaluate the damping performance in practical engineering.

Life safety in single story steel frame buildings, part I – deterministic design

Purpose This paper aims to discuss fire safety design of single-story, single compartment buildings and evaluates whether time to structural damage is a relevant criterion when lethal fire conditions develop long before any structural fire damage can occur. Design/methodology/approach The proposed approach is demonstrated in a design case study of a steel truss in a typical Swedish single-story steel frame building. Findings While not complying with deemed to satisfy fire resistance ratings, it is argued that the proposed design still can fulfill the life safety objective. Originality/value This paper presents practical application of a conceptual paper presenting a general approach to structural fire safety design and the life safety objective.

Gusset design considering buckling forces in frame and brace action directions: Test and finite element analysis of a self-centering braced frame for verification

A steel dual-core self-centering brace (DC-SCB) has been developed to combine both energy dissipation and self-centering properties into a single member for seismic resistance. A strong gusset-weak brace design assures the seismic response of the DC-SCB in earthquakes. In this work, in-plane cyclic tests and finite element analyses were conducted on single story steel frames with the DC-SCB to investigate the performance of corner gusset plates due to the brace axial force (which acts in the direction of the brace) combined with the force from the frame action (which acts in a direction near perpendicular to the brace axial force). Different configurations of gusset plates were used for analyses to develop a design method to consider effects from brace forces and frame action forces. The yielding and buckling forces of a gusset plate in the frame action direction are verified based on a proposed column strip model and buckling coefficient varied with gusset thickness. It is shown to be consistent with the behavior from the tests and finite element analyses with errors in strength of up to 13% for the range of gusset configurations considered.

The Static Stability Analysis of Single-Story Steel Frames with I-Section Columns

Static stability analysis to 12 kinds single-story steel frames with I-section columns is analyzed based upon bilinear lateral force versus displacement framework curve and finite element method, then ultimate displacements are obtained. In comparison, the framework curves and ultimate displacement calculated by modified stiffness and cross-section plastic moment theory accord with that calculated by finite element method. This provides the referential basis for the static stability analysis to a single-story steel frame.

Influence of Different Earthquake Excitations on Dynamic Stability of Single-Story Steel Frame

Dynamic stability analysis of twelve single-story steel frame structures is analyzed based upon the finite element method. The influence of different earthquake excitations on dynamic stability of single-story frame is studied. Time history curves of displacement, hysteretic curves of restoring force, phase plane trajectory curves have been obtained. The results indicate that the ultimate displacements of frames when structures collapse are almost identical and ultimate displacements are independent of earthquake excitations.

Out-of-Plane Stability of Buckling-Restrained Braces Placed in Chevron Arrangement

AbstractLarge-scale shake table tests were performed at E-Defense to examine the out-of-plane stability of buckling-restrained braces (BRBs). Two specimens were subjected repeatedly to a near-fault ground motion with increasing amplification. The test specimens comprised a single-bay, single-story steel frame and a pair of BRBs placed in a chevron arrangement. The specimens were not braced at the brace-to-beam intersection in order to produce a condition where the BRBs were susceptible to out-of-plane instability. Standard BRBs were used in the first specimen, while BRBs with a flexible segment at each end of the steel core were used in the second specimen. A simple stability model predicted the BRBs in the second specimen to fail because of out-of-plane buckling. The first specimen exhibited excellent ductility during the shake table tests, while the second specimen developed severe out-of-plane deformation that compromised the ductility of the BRBs. Based on the experimental observations and the stabili...

Clearance Between Single-Story Steel Frames and Firewalls

A simple formula is developed to estimate the separation distance required between single-story steel frames and firewalls so that during an uncontrolled fire the frame can expand without contacting and damaging the wall. Detailed analysis shows that the frames reach their maximum lateral displacement at the birth of plastic hinges in the girders. The hinges allow the girders to sag excessively, pulling inward on the columns and causing the frame to collapse away from firewalls. The simple method presented uses the frame geometry, member cross sections, loads, and the temperature-dependent steel properties to predict the steel temperature at which the plastic hinges form. The formula uses this temperature and the equilibrium of the deformed frame to calculate the minimum acceptable clearance. The fire is assumed stationary and fully developed. The exposed portions of the structure are assumed totally enveloped by the hot gas. The method includes the column resistance to thermal expansion and the plastic deformations that originate from the second-order effects due to the axial loads in columns acting on the deformed frame. The approach lends itself to spreadsheet calculations for fast design decisions and is accurate, which is demonstrated by good agreement with experimentally validated finite element results.

Analysis of masonry infilled steel frames with seismic isolator subframes

The Seismic Infill Wall Isolator Subframe (SIWIS) system is developed for use in building frames with masonry infill walls in order to prevent damage to columns or infill walls and minimize life-safety hazards during potentially damaging earthquakes. The SIWIS system, which consists of two vertical and one horizontal sandwiched light-gauge steel studs with “rigid-brittle” elements in the vertical members, is designed to allow infill wall–frame interaction under wind loading and minor-to-moderate earthquakes for reduced building drift but to disengage them under damaging events. The SIWIS system acts as a “sacrificial” element just like a “fuse” to save the infill wall and frame from failure. Nonlinear finite element models for two cases, a single-bay, single-story steel frame and a two-bay, three-story steel frame, in three forms including bare frame and infilled frame with and without SIWIS system were performed to develop an understanding of how the system responds to lateral loading. Analysis results show that the concept of SIWIS system works in providing initially high stiffness followed by an isolation of infill wall from interaction with the confining frame. Practical design guidelines are proposed and applied to an eight-story office building.

Lateral displacement and collapse of single-story steel frames in uncontrolled fires

In industrial and commercial single-story steel-framed buildings, the collapse mode and lateral displacement of unprotected frames in large uncontrolled fires affect in part the integrity of firewalls. In this study, the complete deformation sequence of frames, from initial thermal expansion, followed by either column buckling or formation of plastic hinges in the beams, to collapse was used to determine the safe clearance required between the frame and the firewall to allow the frame to expand laterally without contacting and damaging the wall. An experimentally validated nonlinear finite element model, using ABAQUS, was developed to simulate the heat transfer to the frame and its subsequent thermal expansion and collapse. Both geometric and temperature-dependent material nonlinearities and creep were included in the analysis. The collapse mode of single-story bare steel frames depends on the fire scenario and could be toward the firewall when fire is localized close to the wall or in the more desired mode away from the wall. Lateral displacement of frames increases with the increase of spatial extent of fire. The greater the roof weight, the sooner the failure will occur and the smaller is the minimum clearance between frames and firewalls. The importance of including creep in analysis increases with higher roof loads and taller columns. Uncertainties in the steel mechanical properties at high temperatures affect the predicted performance of frames and hence the safety of firewalls.

Properties of P/M nickel-based superalloy dual-property discs produced by superplastic forging: Tsuda, O., Kanamaru, N., Furuta, S., Takigawa, H. and Iwai, K. Kobelco Technol. Rev. Oct. 1990 (9), 38–42

The Seismic Infill Wall Isolator Subframe (SIWIS) system is developed for use in building frames with masonry infill walls in order to prevent damage to columns or infill walls and minimize life-safety hazards during potentially damaging earthquakes. The SIWIS system, which consists of two vertical and one horizontal sandwiched light-gauge steel studs with “rigid-brittle” elements in the vertical members, is designed to allow infill wall–frame interaction under wind loading and minor-to-moderate earthquakes for reduced building drift but to disengage them under damaging events. The SIWIS system acts as a “sacrificial” element just like a “fuse” to save the infill wall and frame from failure. Nonlinear finite element models for two cases, a single-bay, single-story steel frame and a two-bay, three-story steel frame, in three forms including bare frame and infilled frame with and without SIWIS system were performed to develop an understanding of how the system responds to lateral loading. Analysis results show that the concept of SIWIS system works in providing initially high stiffness followed by an isolation of infill wall from interaction with the confining frame. Practical design guidelines are proposed and applied to an eight-story office building.

Two-phase model to predict the inelastic, seismic response of a steel frame

Previous papers reported on the use of a nonlinear differential equation (containing a Ramberg-Osgood term) to represent the inelastic, seismic behavior of a single-story steel frame. The structure was tested on the shaking table at the Earthquake Engineering Research Center at the University of California, Berkeley. The correlation between the predicted and measured acceleration time histories was exceptionally good. However, the computed displacement time histories did not predict the permanent offset experienced by the structure. The reason for this shortcoming is that the hysteretic behavior of virgin steel is different in the first inelastic excursion than it is in subsequent excursions. The Ramberg-Osgood model can represent only the subsequent hysteretic behavior. To alleviate this deficiency, the present paper presents a two-phase model. One set of parameters is established for the initial phase of the response, in which hysteretic behavior is approximately elastic, perfectly plastic; and another set is established for the second phase, in which the hysteretic behavior has a more rounded transformation from elastic to plastic deformation. The importance of this work lies not so much in its application to steel, as in its potential for application to degrading materials like reinforced concrete and masonry.