AbstractDrywall partition wall systems have become one of the most common forms of construction for partition walls in multistory buildings around the world. Drywall partitions are usually attached ...to the surrounding structural framing and consequently experience damage as the building moves due to wind and earthquake actions. The damage occurs at very low drift levels, sometimes lower than the design limits set by the current standards. This paper presents an innovative solution for constructing drywall partition walls, which allows the system to be uncoupled from interstory drift within the building. This allows the system to undergo large interstory drifts without sustaining damage. Further, it also allows the system to be ‘quieter’ under smaller serviceability drifts, thereby addressing the creaking problem of partition systems, which has become an issue in recent times in flexible high-rise buildings. The assessment of these systems needs to be performed using three-dimensional assessment methods, due to the interconnected nature of the walls. This has been performed using the Multi-Axis Substructure Testing System at Swinburne University of Technology, which allowed full-scale 3 m x 3 m square room test specimens to be assessed experimentally. The results show superior seismic performance and improved acoustic performance of the newly developed system when compared to traditional partition wall systems.
Sustainability necessitates the protection of infrastructure from any kind of deterioration over the life cycle of the asset. Deterioration in the capacity of reinforced concrete (RC) infrastructure ...(e.g., bridges, buildings, etc.) may result from localised damage sustained during extreme loading scenarios, such as earthquakes, hurricanes or tsunamis. In addition, factors such as the corrosion of rebars or ageing may also deteriorate or degrade the capacity of an RC column, thereby necessitating immediate strengthening to either extend or ensure its design life is not limited. The aim of this paper is to provide a state-of-the-art review of various strengthening and repair methods for RC columns proposed by different researchers in the last two decades. The scope of this review paper is limited to jacketing techniques for strengthening and/or repairing both normal- and high-strength RC columns. The paper also identifies potential research gaps and outlines the future direction of research into the strengthening and repair of RC columns.
•Limited ductile high-strength RC columns are tested under bidirectional earthquake actions.•Axial load ratio and the type of bidirectional loading history are the variables of the study.•A ...non-linear biaxial force-drift backbone model for RC columns is proposed and validated.
This paper endeavors to enhance the understanding of the non-linear force-displacement hysteretic behavior of reinforced concrete (RC) columns subjected to bidirectional earthquake actions with different loading paths and magnitudes of lateral displacement in the two axes. RC column testing in literature has traditionally been focused towards the unidirectional testing of both normal and high strength concrete columns or the bidirectional testing of normal strength concrete columns only. This study will address this important knowledge gap by experimentally investigating the biaxial lateral capacity of high-strength RC columns with limited ductile detailing. The results of this experimental study and other previous studies are also used to develop a simplified model for predicting the non-linear backbone force-displacement behavior of RC columns. The paper will firstly present the six full-scale column specimens, the test setup, and the loading procedure. The test results will then be presented and analyzed. Three different bidirectional loading protocols were adopted to study the effects of loading history. The important effects of axial load ratio on the collapse behavior (i.e. maximum drift) are also examined in detail. The paper will conclude with an overview of the proposed backbone model for predicting the force-drift behavior of RC columns subjected to bidirectional loading.
This paper aims to guide structural engineers on how to apply the rapid nonlinear time history analysis (RNLTHA) procedure effectively to predict seismic demand, taking into account ductility and ...overstrength, and effects of dynamic phenomena including cyclic degradation of strength and stiffness in structures, in a direct and expedient manner. The shortcoming of the conventional force-based approach of design involving the use of a force reduction factor to account for nonlinear effects is well recognised. Nonlinear static (pushover) analysis and dynamic nonlinear time history analysis (NLTHA) are offered as alternative methods of analysis by major codes of practices to achieve better optimisation in the use of materials. NLTHA has advantages over pushover analysis in being more direct and capable of capturing cyclic response behaviour. Despite the merits of NLTHA, its adoption in the industry has been limited, mainly because of the complexity and the higher analysis cost involved. RNLTHA proposed in this article uses a macroscopic model of the building to fulfil the purpose of NLTHA, whilst saving computational time and achieving a good degree of accuracy, as verified by comparison with results generated from SeismoStruct.
This paper is aimed at giving structural designers guidance on how to make use of elastic site-specific response spectra for the dynamic modal analysis of a structure in support of its structural ...design. The use of response spectra in support of the pushover analysis of an RC building forming part of the non-linear static analysis procedure (that can be used to predict seismic demand without relying on the code-stipulated default R factor) is also presented. Seismic analysis of structures based on the use of site-specific response spectra can help to achieve a more optimised, and cost-effective, structural design compared to the conventional approach employing a response spectrum model stipulated by the code for different site classes. Currently, the methodology is only adopted in major projects in which enough resources are available to engage experts who are skilled in operating the procedure; thus, the use of site-specific response spectra in structural engineering practice is still limited despite the merits of the procedure. Deriving a site-specific response spectrum requires a database of representative ground motion records to be developed. Extra analytical tasks to be undertaken include the processing of bore log data, site response analyses, and selection/scaling of bedrock accelerograms for input into site response analyses. Guidelines for implementing this design methodology are currently lacking. To promote the wide adoption of site-specific seismic design, this article presents the procedure for developing the required site-specific design spectra, as well as guidelines for applying these spectra for seismic design based on analyses of linear, or nonlinear, models of the building. Non-linear analysis can be accomplished by dealing with macroscopic models as illustrated in a case study.
AbstractThis study aimed to quantitatively develop realistic quasi-static loading protocols for simulating bidirectional cyclic actions and axial load variation on building columns in a way that is ...representative of an actual response during earthquake ground excitation. A case-study building was subjected to a suite of 15 ground motions that were scaled to design basis earthquake (DBE) and maximum considered earthquake (MCE) levels of a typical region of low-to-moderate seismicity. The results showed that the displacement path of a building column under earthquake actions is generally in the form of elliptical loops of various orientations due to the phase difference in the sinusoidal displacements in the two orthogonal axes of the column. Accordingly, this work proposes a bidirectional lateral loading protocol that simplifies and generalizes the displacement path of the column in the form of elliptical loops of four different orientations. Similarly, the patterns of axial load variation in columns were also studied in detail, which led to the development of separate axial load variation protocols for external and internal columns of a building, which can be applied in tandem with the bidirectional lateral loading protocol. The paper concludes with a brief overview of the results of two reinforced concrete (RC) column specimens, which were experimentally tested using the proposed bidirectional loading protocol.
AbstractThe seismic behavior of ductile high-strength RC (HSRC) columns that are constructed in regions of high seismicity is well understood due to a number of experimental studies conducted over ...the last few decades. However, limited ductile HSRC columns commonly constructed in regions of lower seismicity have received significantly less attention. This paper presents the results of an experimental program conducted to study the collapse behavior of HSRC columns with limited ductile detailing under unidirectional lateral loading. The experimental program included six HSRC columns that were tested under quasi-static cyclic lateral loading until collapse occurred. The variables of the testing program were axial load ratio, amount of lateral confinement, and the concrete compressive strength. The paper concludes with a comparison against a force–drift model developed by the authors, which showed very good correlation with the experimental results.
Columns in building frame systems are subjected to the combined action of bidirectional horizontal loading and axial load variation during an earthquake. Whilst the behaviour of RC columns under ...unidirectional and bidirectional lateral loading with constant axial load is understood well, the behaviour under bidirectional lateral loading with axial load variation is rarely studied, especially for limited ductile RC columns prevalent in regions of low to moderate seismicity. This paper begins with a numerical study that aims to obtain the generalised patterns and range of axial load variation in RC building columns. To this end, a case study building is subjected to a suite of 15 ground motions, representative of low to moderate seismic regions, in OpenSees. This is followed by an experimental study in which limited ductile high-strength RC columns are tested under bidirectional lateral loading and two different axial load variation protocols, namely synchronous and nonsynchronous variable axial loading protocols. The results of the numerical study demonstrated that axial load variation of the columns in an RC building is primarily dependent on the response spectral acceleration corresponding to the fundamental period of the structure in the two orthogonal horizontal directions and/or the vertical direction. The results of the experimental testing showed that nonsynchronous axial loading (compared to constant and synchronous axial loading) results in the lowest collapse drift capacity and energy dissipation of the RC columns.
•Strength/stiffness of stitch plate connections depends on the stud configuration.•The innovative grouted panel pocket is a tested alternative for stitch plates.•Grouted panel pocket was 1.7 times ...stiffer and stronger than the stitch plate.•The innovative post tensioned corbel is a tested alternative for wet joints.•Post tensioned corbel was greater than 40 times stiffer than the stitch plate.
This paper presents the experimental testing and results of a recent study into panel-to-panel connections for jointed precast concrete building cores. Panel-to-panel connections are typically used to transfer vertical shear forces between adjacent panels to allow the individual panels to act as one combined composite cross-section. The experimental program consisted of three specimens, each constructed using a different type of connection. The first specimen was the ‘baseline’ specimen and was constructed using ‘industry standard’ welded stitch plate (WSP) connections. The second and third specimen were constructing using two new prototype connections, which were developed by the authors and are referred to as grouted panel pocket (GPP) and post tensioned corbel (PTC) connections. These connections were developed such that precast concrete building cores could be constructed without the use of wet joints or site welding, which are both costly aspects in precast wall construction. The experimental assessment showed both connections were stronger and stiffer than the baseline WSP connection. The paper is concluded with a detailed overview of the critical failure mechanism of each connection and the development of respective design models that could be used to predict the design performance of the connections.
•Response of RC wall when subjected to static + impact action is investigated.•An analytical model is proposed for estimating RC wall deflection.•Structural response of RC wall is studied in a ...large-scale experiment.•Proposed model is validated by experimental results.
A displacement-based (DB) model is introduced in this article alongside its detailed derivations to predict the flexural response behaviour of a cantilevered reinforced concrete (RC) wall that is subjected to combined actions of boulder impact and sustained load (e.g. debris flow). In order to validate the model, a large-scale experiment was carried out by striking a 1.5 m tall, 3 m long and 0.23 m thick reinforced concrete wall using of two impactors weighing 280 kg and 435 kg to simulate different boulder impact intensities. A sustained load of 36 kN was applied to the wall using two prestressed custom-fabricated spring assemblies. Wall deflection and reinforcement tensile strain values measured from the experimental tests are shown to be within about 10–20% of predictions calculated from the proposed DB model. Errors of the predictions are consistently conservative across all the considered impact scenarios. These experimental findings are original given that no impact tests of the scale presented in this paper, which incorporate the effects of co-existing sustained lateral forces (e.g. debris flow), can be found in the literature. The proposed DB model was found to accurately predict both the deflection of the wall as well as the amount of tensile strain experienced by the reinforcement at the base of the wall. This paper concludes with a step-by-step design procedure that utilises the proposed DB model for designing RC rockfall barriers, which will be useful for practitioners aiming for a more optimised barrier design.
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