Single-story Building Research Articles

Influence of soil structure interaction effects on the real elastic axis of asymmetric buildings

Structural eccentricity plays an important role in the seismic design of buildings. According to various seismic design codes, it is one of the parameters which define whether a building may be considered as regular in plan. Structural eccentricity is defined as the distance between the center of mass and the center of rigidity. However, the center of rigidity is rigorously defined in single story buildings and in some special classes of multi-story buildings, e.g. isotropic ones, under the assumption of fixed based conditions. The present paper deals with single story and multistory asymmetric buildings that possess a real elastic axis under the assumption of fixed base condition and examines the existence or not of an elastic axis under soil structure interaction effects. The flexibility matrix and the loading vector are defined under flexible base assumption and the elastic axis is determined based on the notion of twist center. Mathematical formulas are derived which provide the coordinates of the elastic axis. Numerical examples are presented which investigate not only soil-structure interaction effects but the influence of various loading vectors as well. In general, soil-structure interaction extinct the real elastic axis; hence an optimum torsion axis must be defined. Moreover, soil-structure interaction decreases the structural eccentricity at each story level.

Influence of Modelling Assumptions on the Seismic Risk of Industrial Precast Concrete Structures

This research evaluates the influence of different modelling assumptions on the global and local seismic risk assessment of code-conforming precast reinforced concrete buildings, specifically single-story industrial buildings. In particular the modelling of the system mass, the overhead crane, the beam-to-column and roof-to-beam connections and the cladding system are investigated. For this purpose, a case study resembling a new industrial building designed in accordance with the current Italian building code was selected. Typical dowel beam-to-column connections were considered and the influence of various modelling strategies investigated: perfect hinges, linear elastic connections and non-linear connections with a degrading hysteretic force-displacement model which was calibrated from available data on experimental tests. Three different types of roof-to-beam connections were investigated removing the assumption of rigid diaphragm, namely hot-rolled, cold-formed and socket welded connections. Initially, simplified planar models of single frames were considered to evaluate the influence of the different modelling strategies, then 3D models of the entire building were analyzed. Multiple-stripe non-linear dynamic time history analyses allowed to evaluate displacements, drifts, deformations and ultimate curvatures of the main elements and connections for various intensity measure levels. The seismic risk was assessed in terms of failure rate considering the collapse of both the columns and of the connections. The results show that the beam-to-column connections fail right after reaching yielding due to their low displacement ductility, leading to the loss of support of the beam and therefore increasing the collapse rate of the investigated structural typology.

Elastic axis of special classes of buildings under earthquake excitation

In the present paper the existence of a stable vertical axis of twist in single story and isotropic multistory buildings is investigated. For this purpose, a torsional base excitation is applied at the buildings base and the equation of motion is transformed in the frequency domain. By using the diaphragm constraint equations, analytical formulae are developed which provide the location of the twist axis which is called dynamic elastic axis. It is proved that the coordinates of the dynamic elastic axis depend on stiffness, mass, damping and excitation frequency. Numerical examples are presented. All the results produced by using the developed equations are compared with the coordinates of the elastic axis derived by the application of static forces. The divergence of the two methods is discussed in detail.

Seismic poundings of multi-story buildings isolated byTFPB against moat walls

The gap provided between adjacent structures in the metropolitan cities is mostly narrow due to architectural and financial issues. Consequently, structural pounding occurs between adjacent structures during earthquakes. It causes damages, ranging from minor local to more severe ones, especially in the case of seismically isolated buildings, due to their higher displacements. However, due to the increased flexibility of isolated buildings, the problem could become more detrimental to such structures. The effect of the seismic pounding of moat walls on the response of buildings isolated by Triple Friction Pendulum Bearing (TFPB) is investigated in this paper. To this propose, two symmetric three-dimensional models, including single-story and five-story buildings, are modeled in Opensees. Nonlinear Time History Analyses (NTHA) are performed for seismic evaluation. Also, five different sizes with four different sets of friction coefficients are considered for base isolators to cover a whole range of base isolation systems with various geometry configurations and fundamental period. The results are investigated in terms of base shear, buildings' drift, and roof acceleration. Results indicated a profound effect of poundings against moat walls. In situations of potential pounding, in some cases, the influence of impact on seismic responses of multi-story buildings was more remarkable.

Lateral-torsional seismic behaviour of plan unsymmetric buildings

Torsional response of buildings is attributed to poor structural configurations in plan, which arises due to two factors – torsional eccentricity and torsional flexibility. Usually, building codes address effects due to the former. This study examines both of these effects. Buildings with torsional eccentricity (e.g., those with large eccentricity) and with torsional flexibility (those with torsional mode as a fundamental mode) demand large deformations of vertical elements resisting lateral loads, especially those along the building perimeter in plan. Lateral-torsional responses are studied of unsymmetrical buildings through elastic and inelastic analyses using idealised single-storey building models (with two degrees of freedom). Displacement demands on vertical elements distributed in plan are non-uniform and sensitive to characteristics of both structure and earthquake ground motion. Limits are proposed to mitigate lateral-torsional effects, which guides in proportioning vertical elements and restricts amplification of lateral displacement in them and to avoid torsional mode as the first mode. Nonlinear static and dynamic analyses of multi-storey buildings are used to validate the limits proposed.

Technology of Manufacturing Small Piece Construction Materials Using Ice and Snow

In the study, we present the technologies for manufacturing ice and snow blocks, the strength characteristics of which are sufficient for the construction of temporary low-rise structures (warehouses, garages, hangars, caponiers, and others). A technological feature of manufacturing blocks is the possibility to produce them without using specialized equipment. The technological modes of molding blocks and their thermal-physical and strength characteristics are determined. The blocks and a model of a single-story building with 3×4.2×2.3 m dimensions were tested on resistance to warming in the spring period. The results have revealed the possibility of a wide application of the proposed technologies in the North and the Arctic.

A simplified seismic design method for limited-ductility steel multi-tiered concentrically braced frames in moderate seismic regions

Steel multi-tiered concentrically braced frames (MT-CBFs) represent a bracing configuration where two or more concentric bracing panels are stacked between the ground and roof levels in tall single-storey buildings. A large proportion of MT-CBFs in Canada are located in low-to-moderate seismic regions (seismic category 0–3) where limited ductility CBFs are often preferred in design. Nevertheless, brace tensile yielding may not occur in all tiers of such frames. Additionally, the analysis and design procedure adopted by the 2019 Canadian steel design standard (CSA S16-19) can become tedious in tall frames with multiple panels. In this paper, the seismic behaviour of limited ductility MT-CBFs in moderate seismic regions of Canada is examined to propose a simplified design method. A set of 16 prototype MT-CBFs is designed in accordance with CSA S16-19, excluding the design requirements prescribed for MT-CBF columns. Nonlinear dynamic analyses are then performed to examine their seismic response. Finally, an efficient design method is proposed in the framework of CSA S16-19.

Modeling of the Beam-To-Column Dowel Connection for a Single-Story RC Precast Building

As widely known, connections performance under seismic loads can significantly affect the structural response of RC precast buildings. Within the scientific community, an increasing number of studies has been carried out on this topic, in the light of the recent earthquake aftermaths all over Europe. Indeed, connections turned out to be the weakest part of the precast structures and their failure often provoked the global collapse of the whole building. The present study aims at assessing the seismic behavior of a single-story RC precast building in terms of global collapse implementing two different models of the beam-to-column connection, a simplified and a refined one. A lumped plasticity approach is used to simulate the structural nonlinear behavior at the column base. In order to assess the refined connection model, a preliminary scheme with an isolated single dowel is validated by comparing the pushover outcomes with experimental results from literature. Nonlinear static and dynamic analyses are performed on two models of a 3D single-story RC precast building, one implementing the simple beam-to-column connection model and the other one implementing the refined mode. The comparison clearly shows that the differences are negligible if the global collapse limit state is considered.

A quantitative assessment of greenhouse gas (GHG) emissions from conventional and modular construction: A case of developing country

Building construction serves a vital purpose from a social and economic perspective by meeting the housing needs of society and contributing to the economic growth of a country. However, from an environmental perspective, this sector contributes negatively by releasing tons of greenhouse gas emissions (GHG) in the atmosphere, which consequently gives rise to other environmental hazards such as global warming and ozone depletion. The use of off-site modular construction practices in developed countries is increasing due to its environmental benefits over conventional cast-in-situ method. However, the environmental performance of a construction method may vary across various geographical regions, which is why environmental assessment of construction methods specific to a region is required. This study provides a calculation of GHG emissions in modular and conventional construction methods utilized in Pakistan, considering two single-family single-storey buildings with similar characteristics. The study also provides recommendations to homebuilders for the improvements in low-performance areas in both modular and conventional building methods. The results of the study show that modular building accounts for a total of 3449.73 kgCO2-equivalent GHG emissions whereas conventional building resulted in a total of 6501.91 kgCO2-equivalent GHG emissions. Modular building results in a reduction of 3052.19 kgCO2-equivalent GHG emissions (46.9%) as compared to a conventional site-built building. This implies that the modular construction method is a more environmentally viable option than conventional construction, which needs to be adopted on a large scale to reduce GHG emissions.

THE ANTHROPOGENIC ADAPTATION INDEX OF REPTILES IN URBANIZED AREAS OF THE ASHBERON PENINSULA

The strong urbanization of Absheron peninsula highlights the urgency of studying the level of adaptation of reptiles that characterize these areas. Therefore, we have aimed to study the degree of anthropogenic adaptation of each reptile species inhabiting the peninsula. The anthropogenic adaptation index of separate reptiles in the Absheron Peninsula is different in terms of reproductive strategy. Thus, relatively high adaptive anthropogenic intensity is observed in the Caspian bent-toed geckoes (24.5) which are habitats of single-storey buildings, moderately adapted water snakes (17.2), and poorly adapted Mediterranean turtles (10.4). In the mixed-storey residential area, the anthropogenic adaptation were 21.4, 12.8 and 3.7 respectively in geckoes, water snakes and turtles. The anthropogenic adaptation was 0 due to the absence of water snakes and Mediterranean turtles in the residential area with multi-storey buildings, but the Caspian bent-toed gecko was rarely found (1,3). In the area of industrial facilities, the Caspian bent-toed gecko predominates over the reptile species studied, but the level of anthropogenic adaptation in woodlands and control area was much lower.

Study on Seismic Capacity of Single-story and Brick-concrete Structure Building in a Rural Area of Southern Guangxi

Based on the investigation and analysis of the brick-concrete and single-story houses in a rural area of southern Guangxi, the author established four different overall models of single-story house according to a certain proportion by ABAQUS-a software of finite element analysis, so as to analyze the seismic response of brick-concrete and single-storey buildings in this area under the action of 6-magnitude frequent earthquake. The results show that, under the action of 6-magnitude frequent earthquake, if the single-storey and brick-concrete house is built without reinforced concrete, its wood beam support or column support cannot reduce the stress concentration of the structure obviously;the displacement deviation between the top and the middle of the outer wall can be reduced when the wood beam is used as the support between the inner wall and the outer wall.

Thermal management of metal roof building using phase change material (PCM)

The energy consumption of the buildings for cooling, especially during the days of high solar exposure is large due to the increased indoor temperature. The roof of the building contributes more for this cause by allowing a large quantity of heat during day hours. Further, the single storey buildings with the metal roof would help to penetrate a greater quantity of heat and increase the total heat gain of the building. In this way, they could increase the cooling load to attain the human comfort. In this current work, an experimental investigation was carried-out to reduce the indoor temperature of the metal roof single storey industrial building with the help of paraffin based phase changing material (PCM). In this fashion, an attempt was made to reduce the total cooling load of the building which can diminish a greater quantity of conventional power requirement. A scale model of the proposed building was fabricated and tested for the analysis. The experiments conducted in two modes such as the first case without any PCM in the roof (Plain Roof) and next case with encapsulated paraffin as PCM within the roof (PCM Roof). The test results proved that the encapsulation of PCM within the metal roof of the single storey building reduced the temperature of the outer roof, inner roof and consequently the indoor temperature of the building space to a vast extent. Quantitatively, the daily average indoor temperature was dropped by 5 °C and peak indoor temperature was reduced by 9.5 °C with the help of PCM.

Comfort in Australia’s Unproductive North and the Attendant Anxiety of Tropical Cyclones

In 1922, the Commonwealth Bank opened in Cairns, North Queensland, on the corner of Abbott and Spence Street, not far from the Esplanade and the waters of the Trinity Inlet. A single-story timber building, “bolted together” and pinned to the ground by sunken concrete piers, the structure was described in the local press as “cyclone proof” and the strongest timber building in Australia. Cooled by fifty exhaust vents and simplex windows, the banking chamber also met the requirements of its tropical context and was described as an “ideal office interior” in which the “health and fitness of the staff have been considered in all essentials from first class sanitation to an up-to-date ventilation system.”In this paper the entanglement of comfort—the health and fitness of the bank’s workers, both physical and psychological—with the bank’s design—both tropical and cyclone proof—will be examined. I will argue that the Commonwealth Bank was an early example of a commercial building designed to respond to tropical cyclones, a common occurrence in Northern Australia, but one which had little impact on the planning and construction of buildings at this time. While the bank was built to replace an earlier, smaller building inadequate to the institution’s needs, it was also a direct response to a catastrophic cyclone—the strongest on record—which hit Cairns and surrounding districts on February 2, 1920. Devastating the city and neighboring towns, the cyclone produced a significant storm surge, described in the press as a “tidal wave,” that inundated the city’s central business district, including Abbott Street, where the bank building was located. The structural properties and technical innovations of the new building effectively addressed the anxieties that this event, and subsequent cyclone seasons, would continue to evoke.It will also be argued that the bank building and its widely publicized innovations were part of a larger campaign by the institution (and other northern businesses) to attract staff from the cooler southern parts of Australia (Brisbane, Sydney, and Melbourne), and particularly men (managers and accountants) with wives and children. Promising both safety and comfort for its workers and their families, the bank, it will be argued, also sought to counter the popular conviction that Northern Australia was not suitable for settlement and must remain empty and unproductive. This was achieved by the banking corporation through the national promotion of the lifestyles (and especially sporting activities) of the bank workers, the climatic suitability of the bank buildings, and the technical innovations that ensured it was “cyclone proof.”

Modelling emergency evacuation from an industrial building under spreading fire using a social force model with fire dynamics

Abstract Study of human evacuation from industrial buildings under spreading fire is a challenging research area. Modelling evacuation dynamics under spreading fire is crucial to evaluate the crowd risk and safety in emergency evacuation. The paper presents a crowd dynamics model for emergency evacuation from an industrial building under spreading fire. This model is formulated by integrating a social force model with fire dynamics to investigate the evacuation process under spreading fire. The evacuation model was implemented in MATLAB to simulate the human dynamics for evacuation from a large single-story building under fire with a single exit door. The test results demonstrate that the overall evacuation time was affected by numerous factors for instance: fire spreading rate, crowd density and exit-width. The proposed model can be used to simulate the efficiency of the evacuation process from an industrial building, and thus, it can enhance the design of industries to increase the safety level.

Nonlinear Analysis of Steel Structure Bent Frame Column Bearing Transverse Concentrated Force at the Top in Factory Buildings

The steel bent frame structure of single-story factory buildings is actually a spatial structure system. Different bent frame columns are connected with the roof of bent frame structure, making the columns work and bearing the load together. In the steel frame of the factory building with bridge cranes below 20 t, variable-section columns with corbels are used to bear the crane load. In this article, the steel bent frame column of single-story factory buildings was taken as the research object. The bent frame column was simplified as a cantilever variable stepped column bearing a transverse concentrated force at the top. After simplifying the model, the theoretical formula of deflection, rotating angle, and bending moment of the compression rod was put forward. Moreover, bending deformation and stability of variable stepped columns were analyzed in order to obtain the theoretical and practical formula, then the ANSYS software was used to simulate the bent column.

Assessment Methods for Fire Durability of Intumescent Fire Protection Coatings

Fire durability of intumescent coatings is their ability to retain their fire-protective properties under fire conditions (under the influence of real temperature conditions of fire). The peculiarities of application of intumescent fire-protective coatings in single-storey buildings on the steel frame with account of fire load are considered. In this study, the fire hazard assessment of single-storey buildings on a steel frame with the use of sandwich panels as enclosing structures is made. The analysis of fire load values has been made. Numerical experiments on estimation of the indoor fire temperature regime have been carried out. For estimation of influence of temperature modes of fire on fire resistance of steel structures the software complex “Fire Dynamics Simulator” was used, which implements the field mathematical model. Various fire temperature modes (temperature-time dependencies) were obtained. Modelling of fire temperature modes was performed without taking into account active fire protection systems. The most critical and unfavourable by their consequences fire scenarios, used later for solving the heat engineering problem, have been chosen by experts. Numerical experiments on heating of steel structures were carried out by solving the heat engineering problem in conditions of non-stationary heat influence at standard temperature conditions according to ISO 834 and at fire temperature conditions obtained by modelling results. The estimation of equivalent fire duration on loss of bearing capacity for steel structures is made. ANSYS mechanical” computing complex was used for modelling the heating of steel structures, which allows us to perform heat engineering calculation of the structure on the basis of its software model.

Structural Performance of Straw Block Assemblies under Compression Load

Background:In recent decades, the enduring interest and continued development of straw bale as a walling material are based on its beneficial properties. Straw bale is a biomaterial that contributes greatly to carbon footprint reduction and offers excellent thermal insulation. It is proved that plastered straw bale assemblies have good mechanical properties and can be used for the construction of a single storey building. It is known that straw bale presents high displacement in the assemblies; thus, pre-compression is a major step that helps to push down straw bale so as to avoid future structural failure in the wall. There is no clue yet if this method is structurally beneficial than to stabilized single straw bales before assembling them into a structural panel.Objective:This paper presents the structural performance of straw block assemblies under compression loads.Method:Straw blocks and mortar were used to construct plastered and un-plastered wall panels, which were tested under uniformly distributed compression load till failure.Results:The results obtained show that plastered straw block assemblies can support at least 286 KN/m2, which is higher than the minimum slab load 18.25KN/m2, including imposed load for a residential house. In addition, the strength of plastered straw block assemblies plastered with cement-gum mortar, 0.3 N/ mm2is greater than the strength of a single storey building (0.19N/mm2). Furthermore, results indicate that un-plastered and plastered straw block assemblies perform better than un-plastered and plastered straw bale assemblies. Plastered straw block assemblies support up to 52KN while plastered straw bale assemblies support only 41.1KN.Conclusion:Under compression load, straw block assemblies have a load carrying capacity greater than the minimum slab load. Therefore, Straw block can be used for the construction of a single storey building.

Real-Time Hybrid Test Using Two-Individual Actuators to Evaluate Seismic Performance of RC Frame Model Controlled by AMD

Seismic responses of a single-story RC frame building model under control using an active mass damper (AMD) are demonstrated through a real-time hybrid simulation (RTHS) method. In this study, the RTHS test is carried out by using a hydraulic actuator and a shaking table under a synchronization. Most parts of the target RC frame model are provided as an analytical model for an online computer simulation, and the only single column of the first story is prepared as an experimental substructure. A hydraulic actuator deforms the actual RC column, and uncertainty or nonlinearity of the RC column’s behavior is focused on this RTHS test. At the same time, a control device of AMD is actually tested under a situation of installing it on the target building's floor. The floor response of the target building model is generated using a shaking table. A control motion of the AMD is manipulated based on an online simulation of the entire RC building model. Firstly, a time delay compensation of the hydraulic actuator is considered. Time delay parameters are identified using a combination model of a time lag and a first-order delay. A PID controller and a time series compensator (TSC) are applied to improve actuator performances. Next, the reproducibility of the RTHS test using two-individual actuators is evaluated. The tracking of a restoring force and deformation of the actual RC column specimen generated by the hydraulic actuator and floor motion responses reproduced on the shaking table are investigated. To improve the online numerical simulation based on the measured force responses of the RC column specimen, a high-pass filter (HPF) is applied for a force correction to utilize its phase-lead property. The effect of this HPF force correction is evaluated in both a linear region and a strong nonlinear region of the actual RC column specimen. Finally, the RTHS test results are compared to fully-numerical simulations, and the control effect of the AMD to increase the damping effect for the target RC building model is also investigated.

Estimation Of Drift Limits For Different Seismic Damage States Of Typical Single-story Precast Rc Buildings

In the past earthquakes, the field surveys performed on the single-story precast RC industrial buildings reveal that the main reason for severe damages in those structures were due to the insufficient lateral stiffness. These high period structures exhibit more flexible behavior than conventional reinforced concrete structures. In this study, different code status single story precast RC industrial building models have been considered. Limit drift values for four different damage states such as slight, moderate, extensive, and complete have been investigated based on Park and Ang damage index values. These damage index values are obtained from incremental dynamic analysis. Incremental dynamic analysis is conducted for 25 earthquake ground motion records. The results of current study show that there is an increase in mean drift values obtained for each damage case taken from low code to high code. In the final step, values of current study are also examined in comparison with the values recommended for low-rise prefabricated building class in HAZUS. It is believed that the limit drift values presented in the study will allow a practical and rapid evaluation of the vulnerability of the considered structure.

Evaluation of AISC Seismic Design Methods for Steel Multi-Tiered Special Concentrically Braced Frames

Steel multi-tiered concentrically braced frames (MT-CBFs) are commonly used in North America as a lateral load resisting system of tall single-story buildings. Past studies show that MT-CBF columns designed in accordance with the 2010 AISC Seismic Provisions are prone to buckling due to a high axial compression force combined with in-plane bending moments caused by the nonuniform distribution of inelastic brace deformations along the frame height. Special design provisions have been introduced in the 2016 AISC Seismic Provisions to address flexural demands imposed on MT-CBF columns and prevent column instability. In this paper, the seismic design methods for multi-tiered special concentrically braced frames are evaluated using the nonlinear finite element analysis method. A two-tiered special concentrically braced frame was then created, and nonlinear static and dynamic analyses were performed to evaluate the seismic performance of both frames. Analysis results confirmed that the inelastic deformations in the frame designed using the 2010 requirements are not uniformly distributed but rather concentrated in one of the tiers and cause column instability under large story drifts, whereas, the 2016 design method significantly improves the distribution of inelastic deformation along the height of the frame and prevents column instability. Furthermore, it was found that the 2016 AISC Seismic Provisions accurately estimate the axial load but overestimate the in-plane flexural demands and underestimates the out-of-plane flexural demand. Nonetheless, the overestimation of in-plane flexure demands results in acceptable strength capacity even though out-of-plane flexural demands is underestimated.