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The viscoelastic damper represents a significant technological advancement in the field of energy dissipation, with the objective of mitigating vibrations in engineering structures that may be caused by seismic activity or wind. The damper is composed of steel plates and a viscoelastic material. In this study, the finite element program Extended Three-Dimensional Analysis of Building System (ETABS) was employed to create a three-dimensional numerical model of a steel building equipped with a viscoelastic damper. The study identifies the optimal location for the damper, assesses its performance under different configurations, and illustrates its efficacy. The findings indicated that the installation of the viscoelastic damper in a ten-story building resulted in a reduction in maximum displacement during seismic events. Furthermore, the study compared the performance of various damper types, including diagonal, chevron, and upper toggle friction dampers, at different levels of the building. The findings indicated that when positioned in the mid-story of the model, the upper toggle friction damper resulted in a 37% reduction in maximum displacement, thereby demonstrating its superior effectiveness in enhancing structural resilience. [ABSTRACT FROM AUTHOR]

This study investigates the seismic behavior of a five-story steel base-isolated building equipped with Lead Rubber Bearings (LRBs). Focus is given to enhancing the damping of LRBs, from 10% to 30%, and its impact on seismic response. We specifically examine the story drift and acceleration under seismic excitations applied through 21 different time histories. The findings reveal that increasing the LRB damping to a range of 15-20% significantly improves the seismic performance of the building, effectively reducing both story drift and acceleration. These results underscore the importance of optimal damping levels in LRBs for enhancing the seismic resilience of base-isolated structures. [ABSTRACT FROM AUTHOR]

Determining the impact of pulse-type earthquake characteristics on the vulnerability of base-isolated buildings under non-pounding conditions has yielded conflicting results in previous studies. Moreover, this issue has received less attention for pounding conditions, especially floor-to-floor pounding. Therefore, this study aims to investigate the correlation between pulse-type earthquake characteristics and the seismic response of buildings under both pounding and non-pounding conditions. In the first stage, three base-isolated buildings and one fixed-base building are analyzed separately under 40 pulse-type earthquakes using the nonlinear time history method. Three scenarios are then considered to account for pounding with adjacent buildings. In the first pounding scenario, a base-isolated building with an intermediate moment frame (IMF) is placed between two fixed-base buildings. The second scenario involves changing the base-isolated building's superstructure system to a special moment frame (SMF). Finally, the third scenario increases the base isolation period (Tb) of the base-isolated building used in scenario two. The correlation between earthquake characteristics and the seismic response of buildings is assessed by linear regression and the Pearson correlation coefficient. The results demonstrate that peak ground acceleration (PGA) has a strong correlation with the seismic response of buildings under pounding conditions, while peak ground velocity (PGV) shows a stronger correlation under non-pounding conditions. However, predicting building vulnerability with a single pulse-type earthquake characteristic remains unreliable unless a large number of ground motions are considered. Otherwise, it is crucial to consider the correlation of all earthquake characteristics with seismic responses. [ABSTRACT FROM AUTHOR]

Due to increasing awareness of human safety, Indonesia has mandated that all operational buildings obtain a Certificate of Occupancy. Consequently, existing structures must undergo a structural assessment before being granted this certificate. Evaluating older buildings poses significant challenges, especially when comprehensive records are lacking, and budgets do not allow for Non-Destructive Testing (NDT). This study presents the structural evaluation findings of a three-story steel building in Jakarta. Using visual inspections, field measurements, and limited available data, an analytical model representing the building's actual condition was developed. The evaluation followed three procedures: Tier 1 and Tier 2 evaluations of ASCE 41-17 and proportional seismic forces. These procedures aimed to gauge the structural integrity and identify areas vulnerable to failure during a severe earthquake. The assessment focused on the ductility of the seismic force-resisting system components and the strength of beam-column joint connections against specified acceptance criteria. The findings highlight critical insights into the building's structural performance, informing decisions on necessary measures such as structural reinforcement, occupancy restrictions, or demolition. This study underscores the importance of thorough structural assessments in ensuring the safety and resilience of older buildings in earthquake-prone regions. [ABSTRACT FROM AUTHOR]

Determining the impact of pulse-type earthquake characteristics on the vulnerability of base-isolated buildings under non-pounding conditions has yielded conflicting results in previous studies. Moreover, this issue has received less attention for pounding conditions, especially floor-to-floor pounding. Therefore, this study aims to investigate the correlation between pulse-type earthquake characteristics and the seismic response of buildings under both pounding and non-pounding conditions. In the first stage, three base-isolated buildings and one fixed-base building are analyzed separately under 40 pulse-type earthquakes using the nonlinear time history method. Three scenarios are then considered to account for pounding with adjacent buildings. In the first pounding scenario, a base-isolated building with an intermediate moment frame (IMF) is placed between two fixed-base buildings. The second scenario involves changing the base-isolated building’s superstructure system to a special moment frame (SMF). Finally, the third scenario increases the base isolation period (Tb) of the base-isolated building used in scenario two. The correlation between earthquake characteristics and the seismic response of buildings is assessed by linear regression and the Pearson correlation coefficient. The results demonstrate that peak ground acceleration (PGA) has a strong correlation with the seismic response of buildings under pounding conditions, while peak ground velocity (PGV) shows a stronger correlation under non-pounding conditions. However, predicting building vulnerability with a single pulse-type earthquake characteristic remains unreliable unless a large number of ground motions are considered. Otherwise, it is crucial to consider the correlation of all earthquake characteristics with seismic responses.

The pre-engineered steel framed structure (PEB) introduced in 1960’s includes a structural frame, roofing system and wall supports; for the construction of industrial structure like ware houses, car showrooms, workshops, function halls, stadiums, aircraft hangars etc. is found to be economical, light weight and fast erection process. The PEB’s are built to perform some important functions, provide enough space for storing goods; aircrafts etc.. and protecting the storage items against natural disasters, wind forces, and rain. In this research work a hangar for airbus A-380 has been designed considering its dimensions; for maximum span of 120M and width of 115M and a height of 30M as a pre-engineered framed structure. For designing the structural members staad pro (V8i) software is used. This structural design is in accordance with the specification of the general construction in steel confirming to IS:800-2007 (limit state design) and wind application as per latest code confirming to IS:875-2015 ( part-III) and earthquake analysis has been done as per IS-1893-2016 (part-IV). For the first time a hangar for A-380 has been designed for using above IS Codes, structural design details, connection details have been produced and found that the total steel is 3502.43 Metric Tons.

The pre-engineered steel framed structure (PEB) introduced in 1960's includes a structural frame, roofing system and wall supports; for the construction of industrial structure like ware houses, car showrooms, workshops, function halls, stadiums, aircraft hangars etc. is found to be economical, light weight and fast erection process. The PEB's are built to perform some important functions, provide enough space for storing goods; aircrafts etc. and protecting the storage items against natural disasters, wind forces, and rain. In this research work a hangar for airbus A-380 has been designed considering its dimensions; for maximum span of 120M and width of 115M and a height of 30M as a pre-engineered framed structure. For designing the structural members staad pro (V8i) software is used. This structural design is in accordance with the specification of the general construction in steel confirming to IS:800-2007 (limit state design) and wind application as per latest code confirming to IS:875-2015 (part-III) and earthquake analysis has been done as per IS-1893-2016 (part-IV). For the first time a hangar for A-380 has been designed for using above IS Codes, structural design details, connection details have been produced and found that the total steel is 3502.43 Metric Tons. [ABSTRACT FROM AUTHOR]

Summary: This paper presents a new approach to the project of steel buildings, mainly focused on the architectural, structural, and seismic design of stairs. The objective is to design a structural stair system capable of controlling seismic damage and contributing to the bracing system of the building. The article begins with a review of the seismic standard (ATC, FEMA, and EC8) on which the current design criteria for new buildings with stairs are based. The research is based on two spatial building models (A–B) with the same bracing elements but placed differently. Reference Model A follows classical design approaches. It means, stairs are considered nonstructural elements that do not influence the seismic behavior of the building. This structure corresponds to typical braced frames (IV‐CBF and EBF) according to EC8. Model B includes a stair system designed to help control the effects of inter‐story drifts and inertia forces. In this case, the same bracing elements of Model A were integrated into the stair structure of Model B. A comparative seismic behavior analysis of typically braced frames (A) versus specially braced stairs (B) is presented. The research was based on the static nonlinear (pushover) analysis and the capacity spectrum method (ATC‐40) according to the seismic performance levels (FEMA) and damage limitation (EC8). Finally, the braced stairs was verified via nonlinear time‐history analysis in order to better capture the structural safety of the evacuation routes and their influence on the behavior of the building. This deterministic analysis of the braced stairs verified satisfactory results compared to reference bracing systems. [ABSTRACT FROM AUTHOR]

This paper investigates the effects induced by thunderstorm downbursts to steel building structures that have been previously damaged during strong directivity ground motion events. To achieve this objective, one four-story steel moment-resisting frame that was tested at the E-defense laboratory, Japan was analyzed in the nonlinear range using OpenSees. The seismic response was numerically simulated, obtaining a satisfactory agreement with the experimental evidence, revealing that the effects of such wind events and vertical ground motions were significant. These effects should be addressed during the design of low and medium buildings subjected to initial damage and subsequent thunderstorm downbursts and the ductility demands on structures subjected to multi-hazards can be quantified. The wind loads are applied as an externally applied dynamic load and the revised ductility demands are determined directly. The obtained results are compared to what is expected by experimental tests. [ABSTRACT FROM AUTHOR]

In many situations, not only vertical loads but also lateral loads are taken into account in the design of frame systems. However, although fires are rare events, determining possible behavior changes with the increasing temperature is important for design process. Therefore, the current study presents a numerical examination of the fire behavior of two different buildings with the same geometric properties. For this purpose, 4-story reinforced concrete (RC) and steel-framed building models with four spans in the x and y directions were created. Two spaces, one at the corner and one in the middle of the ground floor were exposed to heat loading gradually from 25 °C to 1000 °C (100 °C each time). The internal forces and time to critical temperature for the columns in these spaces were determined. Furthermore, the effect of temperature on plastic hinge formation was examined and the effect of high temperatures on the design parameters was identified. The results obtained revealed that among RC and steel buildings exposed to the same heat loading, the RC building maintained its integrity and did not reach the collapse state. However, the steel building reached its critical temperature and collapse state in 60 min.

Progressive collapse is the failure of primary structural components produced by natural or abnormal events that may result in a total or partial collapse of the structure. In this paper, several structure models, under different column removal scenarios, were modeled and analyzed using the FE program SAP2000 to evaluate the effect of span length, the strength of structural members, and cross-section on the steel building's resistance against progressive collapse. The Alternative Load Path method was carried out using the linear static and nonlinear dynamic analysis following the GSA 2003 guidelines for this investigation. The material and the geometric nonlinearities must be considered in the nonlinear dynamic analysis. The contribution of span length, steel grade, and cross-section to the response of the structural system was studied through the Demand Capacity Ratio for the linear static analysis. The variation of several parameters, such as bending moments, plastic hinges status and their rotations, displacements, and ductility, was discussed based on the response of the nonlinear dynamic analysis. The main objective of this study is to demonstrate the impact of the latter parameters on the structural enhancement and the reduction of the damage level triggered by the failure of a primary structural component. [ABSTRACT FROM AUTHOR]

Steel buildings are generally susceptible to the risk of progressive collapse in case one or a few load-carrying members are lost in an extreme event such as blast, impact, or fire. Thus, to avoid the catastrophic collapse of steel structures, it is imperative to investigate and learn from the performance of existing steel buildings for progressive collapse potential. The Ohio Union building, a multi-story steel-framed building that existed on the campus of Ohio State University, was tested earlier before its demolition by one of the co-authors for progressive collapse assessment under the successive removal of four columns located at the first-story level. The aim of this study is to conduct NLD (nonlinear dynamic) analysis for the building considering buckling of columns to numerically assess its potential for progressive collapse and then compare it with test observations. The calibrated finite element (FE) model was then extended to incorporate more hypothetical sequential and simultaneous column-loss scenarios. As one of the most widely accepted documents used among practicing engineers for numerical assessment of progressive collapse potential of buildings, the 2003 GSA (General Services Administration) guidelines were also applied. The simplified LS (linear static) analysis approach of the GSA guidelines was used for assessing the progressive collapse risk of the building, and the results were then compared with both test observations and NLD analysis. New dynamic increase factors (DIFs) are recommended for both force- and deformation-controlled actions to be used with the LS analysis.

The effect of crosswind loads on buildings has been studied since the 1980s, but only a few researchers reported on the nonlinear response of tall buildings under ultimate crosswind loads. Performance-based wind design procedures provide a structurally efficient and economical alternative to prescriptive code based design, however their establishment necessitates further research in the following areas: i) development of a straightforward procedure for the derivation of reliable wind time-history loadings from wind tunnel data; ii) assessment of the dynamic behavior of tall buildings excited by wind in the full range of response: linear-nonlinear-near collapse; and iii) quantification of the effect of directionality on building performance in the full range of response. Herein, local aerodynamic data are used to produce reliable estimations of the directional alongwind and crosswind time-history loadings for a 15-storey steel braced frame hospital building, in Montreal, Canada. The case study is designed to withstand the code-based wind and earthquake loads, as independent load combination cases. Then, advanced finite element models are employed to assess the effect of directional alongwind and crosswind loads on the building performance under increasing levels of input wind motion. Ten excitation angles from 0° to 90° are considered. Incremental dynamic analysis is employed to assess the building performance under recurring winds, including the wind directionality effect. To monitor fatigue failure, the rainflow counting method is used to approximate the number and amplitude of loading cycles exhibited by ductile brace members of the lateral force resisting system. • Performance-based methodology for the assessment of wind-sensitive buildings in the linear, nonlinear and near collapse range of response. • Alongwind and crosswind tunnel data for the derivation of reliable wind loadings. • Investigation of the wind directionality effect on the full range of structural response through collapse. • Consideration of fiber-based, nonlinear models for accurate wind response simulations. • Incremental dynamic analysis for alongwind and crosswind excitation, acting at various directions. • Insight in observed alongwind and crosswind failure mechanisms. [ABSTRACT FROM AUTHOR]

Limited research on the pounding of adjacent isolated buildings (floor-to-floor pounding) and conflicting results about the effect of ductility on pounding severity highlight the need for further investigation. Therefore, this study aims to investigate the impact of superstructure flexibility and isolator characteristics on pounding severity and seismic performance of adjacent isolated buildings. To achieve this, several 3D models were designed, and the effects of flexibility variations were examined in four scenarios under pounding. These scenarios involved changing response modification coefficient (Ri), building height, superstructure system type, and isolator period (T b). Due to the time-consuming nature of nonlinear dynamic analysis, the endurance time (ET) method was employed to assess the seismic response. Results indicate that increasing isolator flexibility and decreasing superstructure flexibility led to a reduction in the performance of isolated buildings under pounding. However, these factors were found to have an insignificant impact on the performance of taller adjacent isolated buildings. Furthermore, the critical point for adjacent isolated buildings in most scenarios was found to be the isolated level. • Uncertain effect of isolated buildings' flexibility on floor-to-floor pounding is studied. • Effect of building height, superstructure resisting system, and isolator period analyzed via parametric analysis.. • Isolation level identified as the critical point for pounding in most scenarios. • The performance of shorter isolated buildings worsens by increasing isolator flexibility and decreasing superstructure flexibility. • The flexibility of shorter structures does not affect the performance of the adjacent taller isolated building. [ABSTRACT FROM AUTHOR]

This research examines the effect of plan irregularities on the progressive collapse of steel structures. Firstly, the three structures, regular and irregular are designed. Secondly, the effect of the two plan irregularities on the progressive collapse of moment resisting frame assessed. The collapse patterns of the buildings are analyzed and compared under seven loading scenarios using non-linear dynamic and pushdown analyses. In the non-linear dynamic analyses, node displacements above the removed columns and the additional force on the columns adjacent to them are discussed. Furthermore, the strength and capacity of the columns are compared to determine their susceptibility to collapse. In the non-linear static analyses, the pushdown curve and yield load factor of the structures are obtained after column removal. The results indicate that an irregular structure collapses in most of the column removal scenarios. Moreover, when comparing regular and irregular structures, the demand force to capacity ratio (D/C) of the columns in the irregular structures is on average between 1.5 and 2 times that of the regular ones.

In seismic events, rupture resulted from the earthquake causes two types of ground deformation, namely, the permanent pseudo-static deviations on fault and transient dynamic fluctuations away from fault. Fault rupture extends in soil through bedrock and makes various concerns for structures made by human. On this basis, we examined reverse fault effect on ground-level buildings using numerical analysis and ABAQUS finite-element software. In this regard, some types of buildings were placed on ground near to fault and fault route angle was examined in the presence and absence of building in two layers of soil with different densities. Finally, vertical deformation of ground, horizontal strain of ground, lateral displacement of building, and bending moment of structure were examined beneath fault effect. Results reveal that fault route angle depends on soil layer material, and horizontal strain resulted from fault effect on ground increases by placing building. However, vertical displacement of ground will decrease by placing overhead (building) and the highest part of fault effect will be on columns of first floor.

The Gate to Gellerup is one of the first pilot projects in the ambition Master Plan of Gellerupparken. The new innovative solution of constructions creates a new expression and opportunity to connect Aarhus to Gellerup. Not only does the new Gate improve the connection between areas, the new Gate also allows the inhabitants to pass though the building, as the road runs through the building The stairway no. 44 in the block of flats – B4, fig. 1, has been elevated of the ground, to establish the new Infill project. The Infill project contains three stories of flats and a separate stair‐/elevator tower. In order to maintain the architectural expression of the block and of the flats, and due to the long span of the Infill structure as well as a restriction of maximum thichness of the floor slabs, the existing concrete structure has been replaced by a steel structure, as steel is the only feasible material to obtain slender architectural expression. The aim of the steel design was to find a synthesis of architecture, structural behaviour, productivity and buildability. Structural integrity is achieved by extensive analysis using 3D finite element software and the productivity and buildability was achieved by using simple connections and a continuous focus on easy assembly. The project has been designed by use of Tekla 3D‐model software. The steel structure has been designed in a way, which allows the contractor to assemble the whole steel structure on the ground and then hoist it in place as one assembly. This method was developed in order to achieve optimized period of installation on site. [ABSTRACT FROM AUTHOR]

Fire fragility functions are a powerful method to characterize the probabilistic vulnerability of buildings to fire in the context of urban resilience assessment. But this method is recent and the influence of the different uncertain parameters on the functions has not been systematically studied. The first objective of this paper is to identify the prevailing parameters in constructing fire fragility functions for steel frame buildings. To this end, sensitivity analyses are conducted using Monte Carlo Simulations and a variance-based method, focusing on column failure fragilities. Fragilities for buildings with 3 to 12 stories, 0 to 3 h fire resistance rating and various occupancies are compared, assuming compartment areas ranging from 15 m2 to 80 m2. Results show that uncertainties in fire, heat transfer and structural models all generate significant variability in the fire fragility. In addition to fire load as the intensity measure, significant probabilistic parameters are the compartment geometry and openings, the thickness and thermal conductivity of fire protection, and the temperature dependent mechanical properties of steel. The second objective is to clarify the incorporation of fragility functions in a comprehensive structural fire reliability framework. A methodology for combining the functions with the ignition likelihood per year and with the fire loading in MJ/m2 is described, yielding annual probability estimates of column failure due to fire in the buildings. For a sprinklered office building designed according to prescriptive provisions, this annual probability ranges from 1.90 × 10−7 to 0.12 × 10−7 per year as a function of the building height. The probabilistic modeling techniques proposed in this paper can be used to establish consistent reliability levels in different buildings and to evaluate resilience for fire scenarios. [ABSTRACT FROM AUTHOR]

The application of hysteretic damper has gained major attention in seismic resistant design of buildings. It provides an efficient and cost-effective solution to reduce the level of damage induced on the building due to seismic excitations. The efficiency of the damper is influenced by parameters such as yield strength, yield displacement and brace-damper assembly system stiffness. The premise of this paper is to investigate the effect of the uncertainty associated with the hysteretic damper design parameters on the probabilistic seismic performance of steel buildings. Two steel buildings which are designed in accordance with the European Standard design code are evaluated. The uncertainties associated with the damper design parameters are incorporated using the Optimised Latin Hypercube sampling method for different confidence levels. The building response is obtained by conducting nonlinear time history analyses in OpenSEES. The annual frequency of exceeding a damage limit state, which is quantified by integrating the seismic fragility curves and hazard curves, is computed for the steel buildings with and without consideration of the design parameter uncertainties. • This paper provides a detail seismic performance assessment of steel building with hysteretic steel damper. • The effect of uncertainty in damper parameters on seismic demand on the building was quantified using probabilistic approach. • Seismic fragility curves were developed for steel buildings with and without dampers and variability in drift hazard curves were derived. • Uncertainty of damper properties affect the annual probability of exceedance significantly for immediate occupancy limit state up to 24%. • The effect of damper parameter uncertainty is less conclusive for variability up to 10%. [ABSTRACT FROM AUTHOR]

Performance-based seismic design (PBSD) aims to assess structures at different damage states. Since damage can be directly associated to displacements, seismic design with consideration of displacement seems to be logical. In this study, simple formulae to estimate the peak floor displacement patterns of eccentrically braced frames (EBFs) at different performance levels subjected to earthquake ground motions are proposed. These formulae are applicable in a PBSD and especially in direct displacement-based design (DDBD). Parametric study is conducted on a group of 30 EBFs under a set of 15 far field and near field accelerograms which they scaled to different amplitudes to adapt various performance levels. The results of thousands of nonlinear dynamic analyses of EBFs have been post-processed by nonlinear regression analysis in order to recognize the major parameters that influence the peak displacement pattern of these frames. Results show that suggested displacement patterns have relatively good agreement with those acquired by an exact nonlinear dynamic analysis. [ABSTRACT FROM AUTHOR]

The stick–slip phenomenon is commonly found at structural connections in steel buildings. It is a major damping mechanism in a structure with bolted joints and makes a significant contribution to the total structural damping. This article reviews the stick–slip damping model of an elastic single-degree-of-freedom system with one stick–slip component. It is observed that the damping ratios of the system with the stick–slip mechanism first quickly increase when experiencing a very small displacement and then slowly decrease. After the number of activated slip surfaces is assumed to be a linear function related to the structural displacement, the equivalent damping ratios of a structural system with numerous stick–slip components are derived. However, this displacement-dependent damping model is very difficult to be used for a structural dynamic analysis due to its inherent complexity. Therefore, a new displacement-dependent damping model for a structural dynamic analysis is proposed based on the viscous damping. A high-rise steel moment resisting frame with bolted joints subjected to an earthquake ground motion is taken as an example to verify the proposed method. [ABSTRACT FROM AUTHOR]

A numerical investigation regarding local (µL) and story (µS) ductility demand evaluation of steel buildings with perimeter moment resisting frames (PMRF) and interior gravity frames (IGF), is conducted in this study. The interior connections are modeled, firstly as perfectly pinned (PP), and then as semi-rigid (SR). Three models used in the SAC steel project, representing steel buildings of low-, mid-, and high-rise, are considered. The story ductility reduction factor (RµS) as well as the ratio (QGL) of RµS to µL are calculated. µL and µS, and consequently structural damage, at the PMRF are significant reduced when the usually neglected effect of SR connections is considered; average reductions larger than 40% are observed implying that the behavior of the models with SR connections is superior and that the ductility detailing of the PMRF doesn't need to be so stringent when SR connections are considered. RµS is approximately constant through height for low-rise buildings, but for the others it tends to increase with the story number contradicting the same proportion reduction assumed in the Equivalent Static Lateral Method (ESLM). It is implicitly assumed in IBC Code that the overall ductility reduction factor for ductile moment resisting frames is about 4; the results of this study show that this value is non-conservative for low-rise buildings but conservative for mid- and high-rise buildings implying that the ESLM fails evaluating the inelastic interstory demands. If local ductility capacity is stated as the basis for design, a value of 0.4 for QGL seems to be reasonable for low- and medium-rise buildings. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes an application of tension‐rod displacement–restraint bracing to prevent story drift amplification in tall steel moment frames. Seismic response analyses of a 20‐story bare steel frame are performed first, revealing that story drift amplification occurs in the upper and lower stories at different times. Characteristics observed for the seismic response of the bare frame suggest the efficacy of the delay action of bracing. Subsequently, seismic response analyses of the 20‐story braced frame with tension‐rod displacement–restraint bracings reveals that the increment of the column axial force by addition of bracing is reduced dramatically by the delay action of bracing. The story rotation angles within partial stories where the story drift amplification occurs in the bare frame are also reduced efficiently by the displacement–restraint bracing. The delay action of bracing influences the floor response acceleration and the residual displacement. Finally, parametric analysis results indicate an appropriate value of the story rotation angle at which the brace action starts. [ABSTRACT FROM AUTHOR]

This research examines the effect of plan irregularities on the progressive collapse of four steel structures located in regions with different seismic activity. The plans of the first and second structure are irregular, whilst those of the third and fourth structures are regular. The collapse patterns of the four buildings are examined and compared under seven loading scenarios using non-linear dynamic and static analyses. In the non-linear dynamic analyses, node displacements above the removed columns and the additional force on the columns adjacent to them are discussed. Furthermore, the strength and capacities of the columns are compared to determine their susceptibility to collapse. In the non-linear static analyses, the pushdown curve and yield load factor of the structures are obtained after column removal. The results indicate that an irregular structure designed in site class C seismic zone, collapses in most of the column-removal scenarios. Moreover, when comparing regular and irregular structures designed in site class E seismic zone, the demand force to capacity ratio (D/C) of the columns in the irregular structures is on average between 1.5 and 2 times that of the regular ones. [ABSTRACT FROM PUBLISHER]

There is rising concern among researchers regarding the suitability of structural design for abnormal load resistance. Abnormal loading generated by a blast or impact can cause local damage to a structure that could affect the entire structural system. Structures must be designed to prevent such disproportional consequences. Research has focused on progressive collapse analysis of buildings, most of which are based on the alternative path method and the sudden removal of one or several columns. In this procedure, failure of elements adjoining to the removed columns under blast conditions are ignored, which can lead to an incorrect prediction of progressive collapse. The present study developed a procedure for progressive collapse analysis of common steel building structures subject to blast loading. A 3D numerical model for direct simulation of blast loading is proposed to study the real behavior of a 7-story building under blast loading. A blast load equivalent to 1 t of TNT was simulated at a distance of 4 m from the corner of the structure to assess the direct effect on the structure. The pressure of this blast at 4 levels of loading was applied to adjacent structural members and the structural response was examined and the exciting forces in the adjacent structural members of the blast site were compared. The results indicate that the potential for progressive collapse when assuming blast loading as the initial cause of failure will differ from results of common methods used for evaluation of progressive collapse and in methods that ignore the initial reason for progressive collapse. [ABSTRACT FROM AUTHOR]

This paper presents a damage-evaluation method that estimates the damage level of buildings using ambient vibration measurement and a seismic interferometry technique. A new index, named slowness change and which directly relates the reduction in story stiffness to the vibration signal's travel-time delays in propagating waves, is introduced. The sensitivity of the slowness change to damage was examined through ambient vibration testing for a quarter-scale steel frame, where damage was simulated by removing steel links at member ends. The slowness changes computed from the measurement data increased significantly as the number of fractures increased and the story stiffness decreased. The results showed a strong relationship between the location and amount of simulated fractures and the slowness change. The paper also discusses the signal-processing and measurement parameters required to accurately identify the parameters of the propagating waves, error associated with signal processing and measurement, and a borderline between detectable and undetectable damage for both beam fractures and column fractures in steel frames. [ABSTRACT FROM AUTHOR]

La asociación de un conjunto de contenedores navieros y una estructura metálica de vigas y pilares, que los suspende sobre el terreno, genera una planta baja abierta, una serie de recintos modulares y un proceso de obra tan breve como preciso.A collection of containers combined with a steel structure that suspends them above the ground generates a lower open plan, a series of modular rooms and a brief, precise building process.

This paper presents a comparison of two compartment fire experiments performed on the 9.1 m × 6.1 m composite floors using a full-scale two-story steel gravity frame to study the influence of slab reinforcement on the overall structural integrity. The floor specimens were designed to achieve a 2-h fire rating but had dissimilar slab reinforcement. The Test #1 specimen had steel wire reinforcement of 60 mm2/m width as the minimum permitted in the United States practice whereas the Test #2 specimen was reinforced with deformed steel bars (230 mm2/m) determined by incorporating tensile membrane action. The Test #1 specimen exhibited mid-panel slab integrity failure before reaching the specified fire rating period. However, the Test #2 specimen exhibited much smaller concrete cracks until it was heated up to 131 min and retained the post-fire residual strength at least two times greater than the design demand at ambient temperature. This unique large-scale testing demonstrated that the appropriate slab reinforcement scheme can delay the vertical deflection of the heated composite floor and maintain the structural integrity at large vertical displacements over a longer duration of fire exposure. • The influence of slab reinforcement on the structural integrity of steel-concrete composite floors under fire was evaluated. • Compartment fire experiments were conducted on the composite floor assemblies located in a full-scale two-story steel gravity frame. • Slab reinforcement of larger area and ductility can maintain the structural integrity of the slab for longer period of fire. • The enhanced slab reinforcement significantly delayed the increase in the vertical displacement of the composite floor. [ABSTRACT FROM AUTHOR]

This paper proposes a novel methodology for developing fire fragility functions for an entire steel building – meaning that the function is not specific to a location within the building. The aim is to characterize the probabilistic vulnerability of steel buildings to fire in the context of community resilience assessment. In developing the fragility functions, uncertainties in the fire model, the heat transfer model and the thermo-mechanical response are considered. In addition several fire scenarios at different locations in the building are studied. Monte Carlo Simulations and Latin Hypercube Sampling are used to generate the probability distributions of demand placed on the members and structural capacity relative to selected damage thresholds. By assessing demand and capacity in the temperature domain, the thermal and the structural problems can be treated separately to improve the efficiency of the probabilistic analysis. After the probability distributions are obtained for demand and capacity, the fragility functions can be obtained by convolution of the distributions. Finally, event tree analysis is used to combine the functions associated with fire scenarios in different building locations. The developed fire fragility functions yield the probability of exceedance of predefined damage states as a function of the fire load in the building. The methodology is illustrated on an example consisting in a prototype nine-story steel building based on the SAC project. [ABSTRACT FROM AUTHOR]

Los elementos de mampostería y los miembros de acero usados en la construcción de edificios se mantienen en constante movimiento. Los cambios volumétricos son producto de las variaciones de temperatura y las deformaciones producidas por las cargas estáticas o dinámicas, y en algunos materiales, por los cambios en el contenido de humedad dentro de los mismos, tal el caso de la mampostería. El presente articulo está dirigido a la determinación de cuándo se requieren juntas de expansión o sísmicas, y como proporcionarlas y diseñarlas con propiedad, específicamente en edificios de acero. No se incluye el estudio de las juntas en estructuras de concreto, en muros, ni otros elementos arquitectónicos.