AbstractThe self-centering energy-dissipative (SCED) brace is a new steel bracing member that provides both damping and recentering capability to a structure, while reducing or eliminating residual ...building deformations after major seismic events. Previous SCED brace designs exhibited full self-centering capability over frame lateral deformations ranging from 1.5 to 2.0% of a typical building story height owing to the elongation capacity of the tendons comprising the system. To overcome this limitation, a new enhanced-elongation telescoping SCED (T-SCED) brace has been developed that allows for self-centering response over two times the range achieved with the original SCED bracing system. A prototype design of this proposed system was fabricated and tested quasi-statically and dynamically in a full-scale vertical steel frame. It exhibited full self-centering behavior in a single story frame that was laterally deformed to 4% of its story height. This new T-SCED brace also satisfied standard testing protocols for buckling restrained braces.
•TP-BRB is composed of an inner BRB and an external gap-supported tendon protection.•TP-BRB has stable hysteretic behavior and significant tri-linear characteristics.•Replacing BRB with TP-BRB is ...effective to reduce the maximum and residual story drifts.•TP-BRB shows a negligible effect on the energy-dissipative capacity of steel frames.
For the Buckling-Restrained Braced Frame (BRBF), the reserve strength is critical to reduce maximum and residual drifts, and improve the collapse prevention margin. In this paper, a newly proposed brace is named TP-BRB, which is composed of a Buckling-Restrained Brace (BRB) and a gap-supported Tendon Protection in parallel. Instead of the conventional BRB, the TP-BRB is designed to provide additional stiffness and strength for steel frames after the axial deformation of TP-BRB reaches a threshold value. A quasi-static test of the TP-BRB was conducted to confirm the excellent performance of the new configuration and calibrate the numerical model in OpenSees. Nonlinear time-history analyses were performed to compare the responses of the TP-BRB frame and BRB frame models. The results show that replacing BRB with TP-BRB is an effective means to reduce the maximum and residual story drifts, and increase the collapse prevention margin under strong earthquake; moreover, it reduces the BRB deformation demands without reducing of the energy dissipation capacity of steel frames.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Full-scale shaking table test first conducted on SCMP-BTSF system is reported.•Shear plate walls (SW) is used as replaceable seismic fuse in SCMP-BTSF system.•The SCMP-BTSF test structure displayed ...self-centering behavior and acceptable seismic performance.•Test results show that damage in SCMP-BTSF is consistent with design and only occurs in SWs.•No cracks were observed in concrete floor slabs after shake table tests.
Recent numerical study and cyclic testing results have suggested that the self-centering modular panels (SCMP) offer a promising prefabricated structural panel technology for enhanced seismic performance of beam-through steel frames (BTSFs). Several types of seismic fuse devices, including tension-only braces and slit steel plate shear walls (SWs) for energy dissipation, have been studied for their viability in adoption by SCMP. To further investigate the dynamic response and resilience behavior of this seismic-force-resisting system, shaking table tests have been conducted on a 2-story SCMP-BTSF building model with SWs as seismic fuse device. Two far-field ground motion records with various intensity levels were used in the shake table tests. The presented experimental testing study is the first shaking table test of SCMP-BTSF, which is a newly proposed pre-fabricated structure system with self-centering features. Nonlinear finite element (FE) model was also established to perform time history analysis of the test structure and assist with specimen design. The shake test results show that the structure response under frequent ground motions meets the inter-story drift limit given in Chinese code - GB 50011–2010 (Code for Seismic Design of Buildings, abbreviated as CSDB hereafter). When the hazard level was greater than that of frequent ground motions, the system exhibited flag-shaped hysteresis curves of the story shear as expected. It is observed that the SWs dissipated seismic energy through yielding and buckling of steel slats between slits, while other structural members and PTFs remained elastic. No cracks were seen in the concrete floor slabs after all shake table tests. After replacing SWs, the test structure showed nearly identical dynamic properties and seismic responses to the original test structure.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
► We provided results of experimental study on masonry infilled steel frames. ► Investigations were carried out on different types of masonry infill used in Croatia. ► A new structural solution for ...masonry infill is proposed. ► Comparison between particular structural solutions is provided.
This paper presents results of a part of the Croatian project “Seismic design of infilled frames” and deals with masonry infilled steel frames. The behaviour of steel frames infilled with masonry, commonly used in Croatia, was experimentally investigated under quasi-static cyclic loading. Besides, a new structural solution is proposed. Nine one-bay, one-storey masonry-infilled steel frames with three different masonry infill types: perforated clay blocks (C), lightweight AAC blocks (A) and newly proposed combination of these materials (CA), were built and tested. Proposed combined masonry infill (CA) allowed partial separation of the masonry from the frame at certain drift levels and prevented the infill’s detrimental effects.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Stability functions and the distributed plasticity model are incorporated for fire-structure analysis.•Nonlinear problems are solved by developing a nonlinear thermal incremental-iterative solution ...scheme.•The proposed method can provide more accurate solutions with excellent computational efficiency.•The three-dimensional gradual spread of plasticity under fire loads is captured.•Computational performance is about 10 times greater than Abaqus commercial software.
A novel advanced computational method incorporating the stability functions and the distributed plasticity model into the fiber beam-column element is proposed for the first time to predict the nonlinear inelastic thermo-mechanical behavior of spatial steel frames in fires. The space spread of plasticity is captured by tracing the uniaxial temperature-stress–strain relation of each fiber on sections at integration points. The element stiffness matrix is integrated via the Gauss-Lobatto numerical integration scheme. The nonlinear material behavior is captured by adopting the distributed plasticity model with the force-based interpolation function whereas the geometric nonlinearity of P-δ and P-Δ effects are considered by using the stability functions and a geometric matrix, respectively. The shear deformation and residual stresses which normally exist in steel frames are also considered. For the implementation, a nonlinear thermal incremental-iterative solution scheme based on the Newton-Raphson and Gaussian Elimination algorithm is also developed to address the nonlinear problems due to thermal expansion and material degradation. By taking advantage of the computational benefits of stability functions and the force-based interpolation function, the proposed method offers a novel computational framework for nonlinear structural analysis in a fire with excellent computational efficiency. The reliability and accuracy of the proposed program are verified by comparing the obtained results with results from test data, existing studies, and Abaqus. In addition, the computational performance of the proposed numerical program is about 10 times more effective than the Abaqus commercial software, thus would offer an extremely valuable tool for practical fire resistance designs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Numerical modelling investigation of stainless steel two-dimensional frames in fire.•Validated sequentially-coupled thermal and mechanical numerical model.•Parametric analysis investigating effects ...of key behavioural parameters.•Analysis of results and discussion of structural design implications.
This paper presents a numerical modelling study investigating the response of stainless steel two-dimensional frame assemblies at elevated temperature that has not been the subject of detailed investigation to date. Finite elements models which capture the combined effects of material degradation with temperature and the interaction between the individual frame elements are developed and validated. The effect of key behavioural parameters including frame type, i.e. sway and non-sway, degree of utilisation, material grade and heating profile is investigated through an extensive parametric modelling. A new set of performance criteria in terms of limiting deflection and limiting rate of deflection for sway and non-sway frames in fire is established and verified.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
AbstractThis paper presents the full-scale shake-table test and numerical simulation study results of a 2-story beam-through steel frame (BTSF) equipped with self-centering modular panels (SCMPs) ...subjected to near-fault ground motion records. A SCMP is a portable self-centering device that can be inserted and bolted to steel frames to provide lateral force resistance with recentering capability and replaceable seismic fuse devices for energy dissipation. Previous research works have been done on the analytical study, quasi-static cyclic loading testing, and numerical study of the general seismic behavior of the SCMP systems with different energy dissipation components including tension-only braces, slit steel plate shear walls (SWs), and hysteretic dampers. An important aim of this study is to experimentally verify the seismic performance of full-scale steel frame structures with SCMPs via shaking-table tests capable of applying pulselike ground motion. A literature review of previous research works suggested that near-fault ground motions can amplify the dynamic response of structures and cause more extensive damage compared with far-fault ground motion records. To achieve this goal of studying the effect of near-fault ground motion records on the test structure installed with SCMPs, a nonlinear finite-element (FE) model has been developed for a parametric study in which a set of near-fault ground motion records were used as base excitation to the structure model. The nonlinear dynamic analysis results showed that the test structure exhibited self-centering capability under both design-basis earthquake (DBE) and maximum considered earthquake (MCE) cases. Additionally, the effect of energy dissipation capacity on the test structure’s response is also discussed.
A replaceable rotational viscoelastic damper (RRVD) which has the potential for replacing the existing steel beam-column connections is proposed for steel frame buildings subject to dynamic ...vibrations. The RRVD is used with a sacrificial fuse segment to protect the structure at large inter-story drifts. A low-damage solution for the floor diaphragm with the RRVDs is also proposed. The test result confirms that the failure of the new connection is governed by fuse damage. Moreover, the RRVDs improve the system damping and reduces the earthquake-induced roof acceleration and the peak inter-story drift by up to 30%.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
This study presents a novel approach to detect damage in steel frames using a hybrid network of piezoelectric strain and acceleration sensors. A numerical study has been conducted on a steel frame ...with bolted connections to verify the accuracy of the proposed method. The damage is introduced to the frame structure by loosening the bolts and creating cracks on its structural members. The frame is subjected to cyclic loading. Circular Lead Zirconate Titanate (PZT) piezoelectric transducers and bimorph PZT cantilever plates are used as strain and acceleration sensors, respectively. The strain and acceleration time histories are obtained from the finite element (FE) model. A theoretical model is used to obtain the voltage output delivered by the PZTs. Initial damage indicator features are defined by fitting a Gaussian mixture model (GMM) to the sensors output histograms. Moreover, a new sensor fusion model is proposed to improve the accuracy of the damage detection approach. The numerical results indicate that strain-based sensors and accelerometers are, respectively, more sensitive to cracks and bolt loosening. The hybrid system of sensors is efficient in detecting and localizing both types of damages in steel frames.
•An intelligent damage detection approach using a newly developed self-powered wireless sensor by the authors is proposed.•Acceleration is more sensitive to damages of type bolt loosening/removing.•Strain is affected by local damage events (cracks).•Gaussian mixture model parameters are found to be good damage predictors.•The sensor fusion model provides an insight of the damage location in steel frames.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
This article deals with an experimental program to investigate the in-plane seismic behavior of steel frames with clay brick masonry infills having openings. Six large-scale, single-story, single-bay ...frame specimens were tested under in-plane cyclic loading applied at roof level. The infill panel specimens included masonry infills having central openings of various dimensions. The experimental results indicate that infill panels with and without openings can improve the seismic performance of steel frames and the amount of cumulative dissipated energy of the infill panels with openings, at ultimate state are almost identical. Furthermore, contrary to the literature, the results indicate that infilled frames with openings are not always more ductile than the ones with solid infill. It seems that the ductility of such frames depends on the failure mode of infill piers. This experimental investigation shows that infilled frames with openings experienced pier diagonal tension or toe crushing failure and have smaller ductility factors than those frames with solid infill. Furthermore, a simple analytical method is proposed to estimate the maximum shear capacity of masonry infilled steel frames with window and door openings.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
