This study investigates the failure mechanisms and strength of plate-tube-connected circular steel arches. The upper and lower chord of the arch are joined by a series of uniformly distributed steel ...plates in a radial direction. The chord of the arch mainly bears bending moment, shear force and axial force. The connecting plates mainly resist bending moment, so its failure mechanisms and strength design are different from the traditional truss arch with diagonal tubes and web-opening arches. In this paper, the finite element (FE) software ABAQUS is used to study the in-plane failure mechanism and stability bearing capacity of planar plate-tube-connected circular steel arches, which is subjected to full-span uniform radial load (FSURL), full-span uniform vertical load (FSUVL) and half-span uniform vertical load (HSUVL). The elastic buckling load formula of two-hinged plate-tube-connected circular steel arches is proposed under FSURL.. Also, the limited condition of avoiding local buckling is also proposed under FSURL. The stability bearing capacity design formula of the arch under FSURL is proposed. Studies have shown that under FSURL, the arch will be subjected to global elastoplastic failure, and the upper chord will exhibit a full-section yield at the scope of 1/4 L span and the lower chord will exhibit a full-section yield at the scope of 3/4 L span. Under F(H)SUVL, the global failure mode may occur. The global failure stability bearing capacity design formulas of the arch under FSUVL and HSUVL are also proposed. The FE results are in good agreement with these formulas. Finally, the design suggestions of plate-tube-connected circular steel arches are proposed.
This paper is a companion to “Displacement-Based Method of Analysis for Regular Reinforced-Concrete Wall Buildings: Application to a Full-Scale 7-Story Building Slice Tested at UC–San Diego” and ...presents key results obtained from a full-scale 7-story reinforced concrete building slice built and tested on the George E. Brown Jr. Network for Earthquake Engineering Simulation Large Outdoor High-Performance Shake Table at the University of California, San Diego. The building was tested in two phases. This paper discusses the main test results obtained during Phase I of the experimental program. In this phase, the building had a rectangular load-bearing wall acting as the main lateral force–resisting element. The building was subjected to four historical California input ground motions, including the strong-intensity near-fault Sylmar record, which induced significant nonlinear response. The test addressed the dynamic response of the building, including the interaction between the walls, the slabs, and the gravity system as well as four issues relevant to construction optimization: (1) reduction in the longitudinal reinforcement; (2) use of a single curtain of reinforcement to transfer shear; (3) constrain of plasticity in the first level of the wall using capacity design; and (4) use of resistance-welded reinforcement in the boundary elements of the first level of the walls. The building responded very satisfactorily to the ground motions reproduced by the shake table and met all performance objectives. The effects of kinematic system overstrength and higher modes of response in the experimental response were important; this verified to a large extent the displacement-based method of analysis presented in the companion paper.
•Yielding of serially arranged ductile connections does not occur systematically.•Steel commonly used in timber connections shows unfavourable characteristics.•Using steel with favourable ...post-elastic characteristics enables serial yielding.•Steel with favourable post-elastic characteristics also increases the resistance.•Optimized steel quality could lead to a reassessment of some design principles.
In the seismic design of structures according to the dissipative structural behaviour, the connection ductility is crucial in order to ensure the desired level of energy dissipation of the overall structure. Therefore, in case of ductile zones composed of dowel-type fasteners arranged in series, it is important to ensure that all the fasteners can fully develop their energy dissipation capacity by plastic deformations. However, when different types of connections made of two symmetrical and serially arranged assemblies of dowel-type fasteners are tested, it often appears that only few fasteners fully work in the plastic region while most of the remaining ones exhibit very low yielding.
Looking at the causes of this dysfunction, a possible explanation is due to the fact that the rules for the seismic design of dissipative zones in timber structures given in international codes and used in common practice often make reference only to the steel quality of the dowel-type fasteners specifying a minimum tensile strength or sometime, like is the case of the current version of Eurocode 8, only to maximum values of the dowel-type fastener diameter and of the thickness of the connected timber or wood-based members. Also, the research conducted so far about the ductile behaviour of serially arranged connections was not focused on the post-elastic properties of steel. However, for the seismic design of ductile zones of other materials, such as for example is the case of reinforced concrete walls, post-elastic characteristics of steel are required for the reinforcing bars, in order to achieve the desired dissipative behaviour.
Inspired by this fact, timber connections composed of serially arranged dowels made of steel grades with different hardening ratio and elongation at maximum tensile stress were fabricated and tested. The purpose of this work is to understand if the use of steel with significant post-elastic properties may help to solve the problem of limited yielding in serially arranged dowel-type connections.
The tested specimens were composed of two symmetrical timber members made of Glulam and LVL connected to two 6 mm thick slotted-in steel plates by means of 9 steel dowels with a diameter of 6.0 mm, which were subjected to monotonic and cyclic tests carried out by implementing dowels made of steel with favourable post-elastic properties.
The results showed that the simultaneous yielding of two serially arranged dowelled assemblies is possible, although not fully. Moreover, assuming as reference the steel grade with the lowest post-elastic properties, the connection ductility and strength measured through monotonic and cyclic tests increased by about 30% for the steel grades with the highest hardening ratio and elongation at maximum tensile stress, whereas the displacement at maximum strength was about five times higher.
In addition, it was found that confinement of the timber members and shaping of holes were crucial in order to avoid undesired and premature brittle failures and to increase the connection strength and ductility.
The results obtained may be useful in order to bring a reassessment of the code requirements regarding the steel properties of ductile connections as well as of certain principles of dimensioning and detailing.
In recent years, the distributed photovoltaic battery (PVB) system is developing rapidly. To fully utilize photovoltaic production and increase the penetration of renewable energy, battery storage in ...distributed photovoltaic systems becomes essential. Despite plenty of studies dedicated to the capacity design and system control strategies under different work conditions, few research pay attention to the sophisticated battery storage aging problem and its effect on the system performance. This paper develops a five-parameter photovoltaic model and the electrochemical lithium battery model for the PVB system considering the residential load uncertainty in the distributed photovoltaic system. The battery and system performance under different capacity design and operation strategies are discussed. The results show that the oversize of the battery capacity design contributes to the capacity loss, leading to the increasement of levelized cost of storage, and the capacity design of 6, 8, 10 kWh under 100 %, 80 %, 70 % state of charge (SOC) charging limit is recommended in this case. Under the 100 % SOC limit, the battery capacity declines by 22 %–28 % annually, which is much higher than the limit of 80 % and 70 %. Meanwhile, the battery lifetime based on recommended capacity design can be improved further by 8.6 %, 4.0 % and 2.0 % with controlling the battery charge rate. Besides, a comparison between the electrochemical and traditional battery models is conducted, demonstrating that both models present a high consistency in system energy flow, while the traditional battery model lacks the internal electrochemical aging mechanism. The electrochemical battery model gives out a more precise battery aging result and reveals the different performances under varied control strategies.
•A precise PVB system model, including the 5p PV model and the electrochemical lithium battery model, is established in this research.•The effect of the different battery control strategies on the performance of the PVB system and battery is investigated.•The recommended capacity design in this case under different control strategy is proposed.•A comparison between traditional battery model and electrochemical battery model is conducted.
Whilst there has been research about reduced web section beams; RWS, their seismic behaviour when they are overlaid by slabs is not well understood. This study addresses this by assessing a ...high-definition finite element representation of non-seismically detailed RWS connections with slabs. The composite action is investigated, focusing on effects of the size and location of the web openings. These connections can reach a 4% interstorey drift, thus comprising special moment frames in accordance with AISC 341. Moreover, beam, column, and joint tearing were avoided entirely, and at the most, brittle failure of bolts in the end plate was observed.
•The static capacity was predicted by the CCD method with a modified embedment depth.•The predominant failure mode in tension is concrete cone breakout.•Increased loading rate results in increased ...anchor capacity in tension .•DIF of 1.1 is recommended for the 6.4-mm, 9.5-mm and 12.7-mm diameter anchors in tension.•DIF of 1.2 is recommended for the 9.5-mm and 12.7-mm diameter anchors in shear.•The use of the 6.4-mm diameter anchors is discouraged under impact loading conditions.
The results of a study initiated to investigate the effects of impulse-type loads on mechanical screw anchors, Titen HD® manufactured by Simpson® Strong Tie Inc is presented in this paper. Three anchor diameters (6.4, 9.5 and 12.7 mm) installed at the manufacturer specified embedment depths were tested under static and impulse-type loading in shear and tension. The static test results showed that anchorage failure was by combined pullout and concrete breakout in tension and steel fracture failure in shear. The failure loads were consistent and predictable by the concrete capacity design (CCD) method under both tension and shear loading. The impact test results on the other hand showed that the anchorage systems achieved higher capacities under the high-strain rate loading conditions, yielding dynamic increase factors (DIF) greater than 1.0. DIF of 1.1 has been recommended for all diameter of anchors tested under the impulse-type tension load. The DIF recommended for the anchors under impulse-type shear loading is 1.2 for the 9.5-mm, and 12.7-mm diameter anchors while the 6.4-mm diameter anchors are not recommended for impulse-type loading because of lower capacities achieved under shear loading.
The three‐segment steel panel damper (TSPD) is a type of shear panel damper (SPD) used for dissipating seismic energy. TSPDs consist of an inelastic core (IC) and two outer elastic joints (EJs), with ...the IC having a weaker shear strength than the EJs. Buckling restraining stiffeners delay shear buckling, and end stiffeners stabilize the IC to facilitate force transfer. However, the fabrication of TSPDs may be costly due to the use of built‐up shapes. This prompted the investigation of a more cost‐effective option, namely the WT‐shapes stiffened steel panel damper (WSPD). The WSPD can be built from a single hot rolled wide flange steel shape with four WT‐shapes cut from it. A practical procedure for seismic design using this method is developed in this study. The design procedure for IC web stiffeners is also considered. We propose elastic stiffness calculation methods for WSPDs, which match the analytical results of the proposed model using commercial software. Two full‐scale 2.6 m tall WSPD specimens were fabricated and tested. Different target IC buckling shear deformations of 0.08 and 0.12 radians resulted in two different stiffener designs for specimen WSPD‐0L2T and WSPD‐1L2T, respectively. The specimens had excellent energy dissipation performance. WSPD‐0L2T IC web buckled later than predicted, while WSPD‐1L2T IC web buckled slightly earlier than expected. The elastic lateral stiffness and maximum shear strength computed from the proposed procedures agree with the experimental results within 5%. The experimental responses of the two specimens can also be accurately simulated using Abaqus finite element model analysis.
Stud connectors are commonly used in steel-concrete composite structures. As high strength concrete (HSC) will be applied in the construction of a composite structure, it is needed to study the ...performance of stud connectors in HSC. In this study, tension (pull-out) tests were conducted on the studs with different combinations of diameters-d(13, 16, and 19 mm) and effective embedment depths-h
ef
(40, 60, and 80 mm) in HSC with a 28-day compressive strength of 88 MPa. Based on the experimental results, the concrete breakout failure mode dominates and only the scenario with the smallest diameter and largest h
ef
is controlled by steel failure mode. Because of high strength, the steel failure occurs at smaller h
ef
/d in HSC than normal concrete. In the concrete breakout failure mode, brittle load–displacement behaviors are presented and the angle of the breakout cone ranges from 30∼35°, which is close to the concrete capacity design (CCD) method. Also, the ultimate tensile strength (N
u
), stiffness, and pre-peak ductility are dependent on h
ef
and diameter. The existing prediction models (CCD method and variable angle cone method) both overestimate the N
u
in HSC, which is due to its lower ratio tensile/compressive strength than normal concrete. Considering the mechanism of how the breakout cone is formed, a modified reduced_CCD method is proposed for predicting N
u
of studs in HSC.
In this paper, application of a structural steel frame system called Knee-element Connections Frame (KCF) is investigated as a seismic-force-resisting system. In this structural system, all ...beam-to-column and knee-element to beam and column connections are simple. This configuration creates a zonular rigid connection instead of concentrated rigid one in moment-resisting frame (MRF). It provides more flexibility in architectural design compared with laterally braced frames and reduces the costs and problems associated with the construction of rigid connections with complete-joint-penetration groove weld in MRFs. Moreover, KCF systems can be retrofitted with low cost, because the knee-elements can be easily repaired or replaced. In this study, two types of yield mechanisms (A and B) are introduced for the seismic design of the KCF system based on the capacity design concept. Then, its detailed seismic design procedure is developed based on mechanism A. For performance evaluation of the system according to FEMA P695 methodology, four sample KCF and special moment-resisting frames (SMRF) are designed and compared in terms of failure mechanism, collapse probability and seismic design parameters (Ω0, R and Cd). The results indicate that although the failure mechanism of KCF and SMRF is similar, collapse probability of KCF is less than SMRF. Moreover, the required ductility for both structural systems is provided properly. Consequently, KCF structural system can be classified in the category of MRFs, also seismic design parameters of SMRF can be used for KCF.
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