Modular construction is becoming more popular worldwide due to its reduced construction time, lower construction waste, decreased on-site labor requirements, among other benefits. However, the unique ...structural characteristics of modular buildings, such as discrete floor diaphragms, limited connections between modules, may result in different behavior during earthquakes compared to conventional buildings. However, the seismic response of modular buildings is not well understood, and the force demand in seismic collectors (i.e., connections between modules and seismic force resisting elements) is not quantified. To address this problem, a 9-story prototype building with reinforced concrete (RC) walls was used to investigate the structural properties and responses of modular buildings. Firstly, a nonlinear numerical model was created to accurately model the RC walls, modular frames, inter-module connections, seismic collectors, and other key structural elements. Elastic modal analysis and nonlinear response history analyses were conducted to assess the building's behavior under seismic loads. Subsequently, a simplified numerical model was developed to investigate the effect of three key parameters: the stiffness of seismic collectors, RC wall strength, and earthquake intensity. It was found that modular buildings with RC walls in the center are torsional flexible. Reducing the seismic collector's rigidity can lead to greater force response in the collector. The maximum forces experienced by seismic collectors at the first floor are sensitive to earthquake intensity but not significantly affected by the RC wall strength. Both an increase in the of RC wall strength and earthquake intensity can lead to an increase in the maximum forces experienced by seismic collectors. The method in ASCE 7–16 substantially underestimated the maximum acceleration coefficients at stories below 80 % of the structural height.
•Nonlinear numerical model with discrete floor diaphragm and inter-module connection.•Modular building with RC walls in the center is torsional flexible.•Reduced rigidity of seismic collectors led to greater force response in them.•Both RC wall strength and earthquake intensity affect force in seismic collectors.•ASCE 7-16 substantially underestimate the maximum acceleration coefficients.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Recent earthquakes have confirmed that non-structural walls interacting mainly with frame structures are severely damaged during seismic actions endangering human lives. The ongoing life after ...earthquakes and major costs for rebuilding are deeply affected. In order to avoid this kind of drawbacks, the present paper suggests the introduction of a set of joints between the structure and the nonstructural closing and division walls. The joints should observe the following: joints will be designed to provide free development of displacements in the plane of the walls with no major interactions in the structure; joints will be designed to provide transmission of the seismic forces acting perpendicularly to the non-structural walls towards the main structure. This paper will include several conclusions concerning the admission, constraint or removal of interactions between the structure and the closing and division walls.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
AbstractExisting approaches used to model the lateral load versus deformation responses of reinforced concrete walls typically assume uncoupled axial/flexural and shear responses. A novel analytical ...model for RC walls that captures interaction between these responses for reversed-cyclic loading conditions is described. The proposed modeling approach incorporates RC panel behavior into a two-dimensional fiber-based macroscopic model. The coupling of axial and shear responses is achieved at the macrofiber (panel) level, which further allows coupling of flexural and shear responses at the model element level. The behavior of RC panel elements under generalized, in-plane, reversed-cyclic loading conditions is described with a constitutive fixed-strut-angle panel model formulation. The sensitivity of model results to various modeling parameters is investigated and results of the sensitivity studies are presented, whereas detailed information on calibration and validation of the proposed modeling approach is presented in a companion paper.
•Self-centering walls with buckling-restrained plates were compared with that with friction plates.•Both wall systems showed excellent self-centering, energy dissipation up to more than 3.5% ...drift.•Frictional energy dissipation is greater and more stable than yielding dissipation.•Wall with friction plates can further work without repair after a major earthquake.•Effects of losses in the friction bolt force and PT force were investigated.
Two new unbonded post-tensioned (PT) self-centering precast concrete wall systems with excellent reparability and seismic resilience are investigated in this paper through cyclic loading testing of four large-scale precast walls. As major innovative features, reparability and seismic resilience of the structures are achieved by using externally connected replaceable buckling-restrained yielding plates (Type I) or friction components (Type II), and steel jackets to confine concrete at wall toes. Both types of wall specimens showed excellent self-centering, energy dissipation, and ductile behavior over 3.5–4% lateral drift without significant strength reduction, demonstrating remarkable advantages over monolithic cast-in-place (CIP) walls and self-centering precast concrete walls with yielding reinforcing bars. The damage in the proposed walls concentrated in the external energy dissipation components, with minor concrete cracking and no concrete crushing at the completion of testing, making repairs feasible by replacing the damaged components. The energy dissipating capacity for the Type II wall was significantly greater than those for the Type I walls at relatively small drift levels due to the large initial stiffness of friction-based damping. As there was no significant damage in the friction damping components throughout testing, the energy dissipation for the Type II wall was much more stable than those for the Type I walls. Comprehensive finite element models were also developed for both types of walls, which satisfactorily captured the global and local behaviors, including prediction of minor concrete damage, steel and concrete strains, and nonlinear behavior of the energy dissipation components. A parameter study was subsequently conducted to investigate the effects of losses in the friction bolt force and PT force on the wall behavior. Overall, both types of walls can be used in the life-line structures that have great demand for fast reparation and restoration of their original lateral resistance and energy dissipation after a major earthquake.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•New material models and model elements are implemented in OpenSees.•MVLEM is simulates effectively flexure-dominated structural component behavior.•SFI-MVLEM captures shear-flexural coupled ...structural component behavior.•OpenSeesWiki pages, user manuals and examples are publicly available.
This paper describes new model elements and material constitutive relationships implemented by the authors into the widely-used open-source computational platform OpenSees (Open System for Earthquake Engineering Simulation), aimed to enhance current nonlinear analysis and response assessment capabilities for reinforced concrete (RC) walls and columns. Classes added to the existing OpenSees library include: (1) the Multiple-Vertical-Line-Element-Model (MVLEM) element with uncoupled axial/flexural and shear responses, (2) the Shear-Flexure-Interaction-Multiple-Vertical-Line-Element-Model (SFI-MVLEM) element with coupled axial/flexural and shear responses, (3) the Fixed-Strut-Angle-Model (FSAM), which is a two-dimensional constitutive model for RC panel elements, (4) an improved uniaxial constitutive model for concrete, and (5) an improved uniaxial constitutive model for reinforcing steel. Representative validation studies are also presented, where the analytical model predictions are compared with results of quasi-static lateral load tests on selected RC column and wall specimens. Response comparisons reveal that the implemented models capture, with reasonable accuracy, the experimentally-observed behavior of the test specimens investigated. Based on the comparisons presented, model capabilities are assessed and potential model improvements are identified.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Quasi-static reversed cyclic testing of slender RC walls.•Effect of bar buckling on the deformation capacity of RC walls.•Effect of boundary zone detailing on buckling tendency of longitudinal ...reinforcing bars.•Design of transverse reinforcement to restrict bar buckling in slender RC walls.
The performance of reinforced concrete (RC) structural walls during the past earthquakes in New Zealand (2010–11) and Chile (2010) have highlighted the susceptibility of these critical structural components to several undesirable modes of failure. One such failure mode is premature buckling of the longitudinal reinforcing bars, which has also been observed in experimental tests of flexurally-dominant structural walls. This paper presents the results of an experimental program investigating the effects of transverse reinforcement detailing on buckling resistance of longitudinal reinforcement located in the boundary regions of RC structural walls. Three large-scale rectangular walls with different boundary zone transverse reinforcement detailing were tested under in-plane cyclic loading. The effects of these three types of detailing are reported in terms of drift capacity, buckling length of the longitudinal bars and cumulative energy dissipation capacity of the specimens. The test results confirm that bar buckling modes depend on transverse reinforcement detailing, which consequently also influences the ultimate flexural deformation capacity of ductile walls. By comparing the responses of the tested wall specimens, the inadequacy of code-compliant transverse reinforcement to restrain bar buckling is discussed and the effect of improved transverse reinforcement detailing (designed using a mechanics-based approach) on deformation capacity of slender walls is scrutinised.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper delves into the innovative realm of 3D wall printing, employing large-scale printers to construct walls layer by layer and aiming to revolutionize traditional house construction. The ...review comprehensively explores the properties of 3D printed walls in both fresh and hardened states, covering aspects like failure modes, quality control, mechanical and non-structural properties, seismic response, and reinforcement techniques. Taking a distinctive perspective, it draws parallels between 3D printing concrete and masonry structures, presenting them as a modernized version of traditional construction. Overlooking aspects like various wall cross-sections, connections to other structural elements (i.e., wall-to-wall, wall-to-roof, wall-to-foundation connections), non-structural wall intersections, and reinforcement techniques are addressed, crucial for successful integration into large-scale projects. The review serves as a cautionary guide to researchers, shedding light on less-explored areas in large-scale 3D wall printing and providing insights for future research directions and potential codes and standards drawing inspiration from masonry walls.
Display omitted
•This study explores 3D wall printing to gather insights into the implementing innovative technology in house construction.•This paper reviews the material's properties and structural integrity to enhance printed walls' efficiency and functionality.•This paper aims to evaluate the performance of 3D-printed walls according to standards for masonry structures.•This review focuses on three pivotal aspects: geometry, reinforcement needs, and essential connection details for walls.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Precast walls with yielding and friction energy dissipation were investigated.•Wall erection process was significantly expedited by eliminating grouting.•External energy dissipation components can ...be replaced for repair.•Desirable ductility, self-centering, and energy dissipation were observed.•Finite element model captured global hysteretic behavior and local responses.
A precast posttensioned concrete wall system with supplemental yielding-based and friction-based energy dissipation is proposed, in which rectangular precast panels are stacked along horizontal joints, and unbonded posttensioning (PT) strands are placed inside ungrouted ducts to connect the panels to the foundation. Specially designed yielding-based and friction-based energy dissipation components are externally connected at the wall base using thru-bolts, thus allowing these components to be replaced after a large earthquake for the wall to regain most of its original lateral strength, stiffness, and energy-dissipating capacity. The proposed walls have a significantly expedited erection process by eliminating the casting and curing time of grout for splicing mild steel bars inside sleeves or corrugated metal ducts. The wall toes are protected by steel jackets from crushing as the walls rock along the horizontal panel-foundation joint at the base. Three wall specimens with varied initial prestress levels in PT strands, amounts of yielding-based and friction-based energy dissipation, and heights of the jacketed region, were experimentally investigated using quasi-static cyclic lateral loading. The test results demonstrated important features of the walls, including low damage and large self centering. The specimens were able to sustain drift levels (4%) much larger than the validation-level drift required by ACI ITG-5.1, with almost no reduction in lateral load from the overall peak applied load in each direction. Both the yielding-based and friction-based energy dissipation components worked as designed, and their combination significantly enhanced the energy dissipation capacity of the walls. A three-dimensional (3D) finite element model was also developed by comprehensively including all structural components and their interactions at the wall base. The model was able to capture not only the global hysteretic response of the walls, but also important local responses, such as concrete damage patterns, strain results, behaviors of yielding-based and friction-based energy dissipation components, and behaviors along the horizontal panel-foundation joints.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Nonemulative precast walls were tested and compared against a cast-in-place wall.•Replaceable, external buckling restrained plates were used for energy dissipation.•Concrete crushing at wall toes ...was prevented by confinement from steel jackets.•Damaged precast wall restored its original seismic capacity after being repaired.•The proposed precast walls showed excellent reparability and seismic resilience.
Previous research has shown that nonemulative (jointed) precast walls with unbonded posttensioning can achieve superior seismic performance (e.g., self-centering) compared to conventional monolithic cast-in-place reinforced concrete walls. However, the progression of significant damage and failure in nonemulative precast walls is through the yielding of ductile steel reinforcing bars (referred to as energy dissipating bars) followed by the crushing of concrete at the wall toes, greatly limiting the ability to repair these walls after a major earthquake. In this paper, a nonemulative precast wall system with replaceable, external buckling restrained plates (BRPs) for energy dissipation, and steel jackets for confinement of the concrete at the wall base is investigated through reversed-cyclic lateral loading tests. Four precast wall specimens with varying cross-sectional area of the BRPs and number of horizontal joints were tested and compared against a monolithic cast-in-place reinforced concrete wall. The precast walls exhibited no significant unrepairable tensile or compressive damage with increasinglateral strength up to 4% drift, showing advantages over the cast-in-place wall and non-jacketed precast walls in previous research. With out-of-plane buckling restrained, the BRPs yielded in tension and compression, providing the precast walls with desirable energy dissipation. To highlight the reparability of the precast wall system, one of the specimens was repaired after being subjected to a complete cyclic loading history up to 4% drift. The repair was done by replacing the damaged BRPs, after which the wall was re-tested. The repaired wall restored most of its original energy dissipation, lateral stiffness, and strength, with limited cumulativedamage in the wall. In general, the proposed precast wall system with buckling restrained plates is desirable for seismic regions, offering excellent reparability and seismic resilience.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PDF
