High Energy Dissipation Capacity Research Articles

Cyclic behaviour of UHPC columns with hybrid CFRP/Steel reinforcement bars

A new type of reinforced concrete column with ultra-high-performance concrete (UHPC) and hybrid carbon fibre-reinforced polymer (CFRP) and steel bars is proposed in this paper. The CFRP bars with an excellent linear elastic property are used in the columns to enable the expected self-centring capacity. Steel bars with good plastic properties and high ductility UHPC were used to maintain the high energy-dissipation capacity of the columns. Four UHPC columns were tested under reversed cyclic lateral loading; the behaviour of the UHPC columns with hybrid CFRP/steel reinforcement bars was analysed numerically using OpenSees, and the influences of the CFRP bars and axial-load ratio on the seismic behaviour of the columns were analysed. The results indicate that the strain in the longitudinal bars at the ultimate state is a crucial criterion for determining the effectiveness of the CFRP bars. The UHPC columns with the hybrid CFRP/steel reinforcement exhibit both excellent self-centring capacity and good energy dissipation when the design axial-load ratio is less than 0.7. The replacement ratio of the CFRP bars is suggested to be 1/3–2/3 so that the self-centring and energy-dissipation capacity of the UHPC columns with hybrid CFRP/steel reinforcement bars can be balanced.

A model for predicting load-displacement hysteretic behavior of PVC-CFRP confined concrete column-ring beam interior joints under low cyclic loading

To investigate the seismic behaviors of the column-beam connection, ten PVC-CFRP confined concrete column-ring beam interior joints (PCCC-RBIJs) and one PVC confined concrete column-ring beam interior joint (control interior joint) are designed and five experimental parameters including the CFRP strips spacing, the ring beam reinforcement ratio, the frame beam reinforcement ratio, the ring beam width and the axial compression ratio are considered. Test results show that the PCCC-RBIJs are damaged by shear deformation while the CFRP strips and PVC tubes are not broken. The hysteretic curves of the PCCC-RBIJs are relatively full, indicating that the specimens have high energy dissipation capacity. The peak load and displacement of the PCCC-RBIJs increase as the ring beam reinforcement ratio, the frame beam reinforcement ratio, the ring beam width or the axial compression ratio increases. The descendent segment gradient of the skeleton curves declines with the increase of the ring beam width or the ring beam reinforcement ratio while it enhances with the increase of the frame beam reinforcement ratio or the axial compression ratio. On the basis of experimental research, a simplified skeleton curve calculation formula is proposed by determining the characteristic points of the skeleton curves, and the hysteretic rule of the PCCC-RBIJs is revealed based on the degenerated three fold line load–displacement (P-Δ) hysteretic model. Subsequently, a model for predicting the P-Δ hysteretic behavior of the PCCC-RBIJs is proposed.

Most suitable types of seismic isolation for use in old mosques in Syria

The article discusses the most suitable base
 isolation bearings from the author's point of view for use in the buildings of
 old mosques in Syria, which are designed to protect such buildings from the
 effects of earthquakes that can occur at any time. Especially since many of
 such buildings have an architectural and cultural value, and are included in
 the world heritage list of UNESCO. Elastomeric
 bearings with high energy dissipation capacity (HDRB), elastomeric bearings
 with lead cores (LDRB), single friction pendulum, double friction pendulum and
 triple friction pendulum sliding (FPS) bearings are considered. What they
 consist of, their characteristics. Three, mosques in Syria that are of a great
 value from the point of view of architecture and cultural heritage are listed
 and described, and conclusions are drawn.

Experimental and numerical study on developed elastomeric layers based on natural and butyl matrix rubbers for viscoelastic dampers

Elastomeric layers, that serve as the base of a viscoelastic (VE) damping system in structures, dissipate energy through shear deformation and transform vibration energy into heat by internal friction between polymer chains. In this study, two compounds, based on natural rubber (NR) matrix and butyl rubber (IIR) matrix, were designed and manufactured. Then, the mechanical and dynamic properties of elastomeric layers were investigated. Dynamic loading tests were conducted on the elastomeric layers using a frequency range of 0.1–1.5 Hz and a shear strain range of 10–150% under harmonic loading in order to analyze their hysteretic behavior. The output of the experiments shows that the both of elastomeric layers have a large deformation capability with a high damping performance, but the IIR damper can provide high energy dissipation capacity compared with the NR damper that has a large restoring force. The results also show an increase in storage modulus and loss factor of VE dampers with increasing frequency and their decrease with increasing strain. However, the dependency of VE damper on strain and strain rate based on NR is more remarkable than that of VE damper based on IIR. The experimental data were also used for validation and calibration of numerical simulation by ABAQUS software. The results proved to be satisfactory.

Green Synthesis of Waterborne Polyurethane for High Damping Capacity

AbstractDamping materials have application prospects in shock absorption and noise reduction due to their ability to convert vibration into other forms of energy dissipation. Although there have been tremendous attempts to prepare materials with high damping performance, it is still a challenge to fabricate materials with excellent mechanical properties and stability while maintaining a high energy dissipation capacity. Herein, damping materials of reinforced waterborne polyurethane by adjusting the ratio of soft and hard segments is reported. As the content of hard segments increases, the content of hydrogen bonds interaction between segments increases and the phase boundaries on the microscopic morphology form which obviously enhances the damping capacity. The ultimate samples exhibit a damping capacity of more than 90% and a toughness of 14.8 MJ m–3, maintaining good toughness while exceeding the damping capacity of the most reported materials. The damping mechanisms are summarized into three aspects, the frication among soft segments, the destruction of hydrogen bonds, and the interface friction between soft and hard domains. This work paves an avenue for the application of waterborne polyurethane materials in kinetic energy buffering and impact reduction.

Design of Flat Vaults with Topological Interlocking Solids

This paper investigates the principles that regulate complex stereotomic constructions as a starting point for the design of a new two-dimensional floor structure based on the principles of TIM (Topological Interlocking Materials). These interlocking systems use an assembly of identical Platonic solids which, due to the mutual bearing between adjacent units and the presence of a global peripheral constraint, lock together to form pure geometric shapes. This type of structure offers several advantages such as a high energy dissipation capacity and tolerance towards localised failure, which has made it a popular research topic over the last 30 years. The current research project includes a case study of an assembly of interlocking cubes to create a “flat vault”. The resulting vault design features a striking appearance and its geometry may be manipulated to achieve different two-dimensional solutions, provided certain geometric conditions necessary for the stability of the system are followed.

Seismic performance of a novel prefabricated beam-to-column steel joint considering buckling behaviour of dampers

A novel prefabricated beam-to-column steel joint (PSJ) for precast concrete structures was proposed in this study. The joint had the advantages of easier to fabricate and more environmentally friendly than existing monolithic joint (MJ) cast on site. Low-yield-point steel 100 was used to fabricate the dampers of the joint to provide a high energy dissipation capacity. In addition, the plastic hinge location of the beam can be controlled in the dampers by the buckling energy-dissipation segments (BEDS) of the dampers. Cyclic loading experiments were conducted on three PSJs and an MJ to investigate their seismic performance. The effects of the BEDS’ slenderness ratio on the seismic behaviour of the joints were studied. According to the test results, the PSJs exhibited higher ductility and energy dissipation capacity than the MJ. The BEDS used in the proposed joint were beneficial for concentrating the plastic deformation in the damper, thus preventing the damage to the concrete beams. The decreased slenderness ratio of the BEDS increased the strength of the PSJ. An analytical model that considering the buckling effect was proposed to evaluate the bending moment capacity of the PSJ.

Evaluation of Structural Behavior of Hysteretic Steel Dampers under Cyclic Loading

This study proposes a relatively simple steel damper with high energy dissipation capacity. Three types of steel dampers were evaluated for structural performance. The first damper with U-shape had two vertical members and a semicircular connecting member for energy dissipation. The second damper with an angled U-shape replaced the connecting member with a horizontal steel member. The last damper with D-shape had a horizontal member added to the U-shaped damper. All the dampers were designed with steel plates on both sides that transmitted external shear force to the energy-dissipating members. To evaluate the structural performance of the dampers, an in-plane cyclic shear force was applied to the specimens. The D-shaped damper showed ductile behavior with excellent energy dissipation capacity after yielding without decreasing in strength during cyclic load. In other words, the D-shaped specimen showed excellent performance, with about 3.5 times the strength of the U-shaped specimen and about 3.8 times the energy dissipation capacity due to the additional horizontal member. Furthermore, the efficient energy dissipation of the proposed D-shaped steel damper was confirmed from the finite element (FE) analytical and experimental results.

Seismic performance evaluation of assembled GCFST column-section steel beam frames with geopolymer concrete walls

A new type of assembled lightweight geopolymer concrete filled steel tube (GCFST) columns frame with controllable deformation connected geopolymer concrete walls (GCW) structure has been proposed in this paper. In order to study the seismic performance of the proposed frame, three full size assembled lightweight GCFST column-section steel beam frame with GCW specimens with different connection forms (GSTFW-2, GSTFW-3 and GSTFW-4) were designed based on an assembled lightweight GCFST column-section steel beam frame specimen with number GSTFW-1. The GSTFW-2 is an assembled lightweight frame with strongly connected geopolymer concrete wall. The GSTFW-3 is an assembled lightweight frame with all around controllable deformation connected geopolymer concrete wall. The GSTFW-4 is an assembled lightweight frame-geopolymer concrete wall with upper and bottom controllable deformation connection. Low-cycle reversed loading experiments of the four specimens are carried out. Based on the experiments, the damage process and failure modes of each specimen are analyzed. The load-bearing capacity, displacement, hysteretic performance, energy dissipation and ductility of each specimen were studied. The results show that the proposed controllable deformation connection has great impact on the seismic performance of the proposed frame. The assembly parts of the assembled lightweight frame are connected reliably with good integrity of the frame, strong elastic-plastic deformation capacity, high energy dissipation capacity and good aseismic performance. The assembly parts have light weight and the construction is simple. It is convenient for popularization and application in rural areas with low degree of mechanization.

Effect of Stiffener Characteristics on the Seismic Behavior and Fracture Tendency of Steel Shear Walls

The steel plate shear walls (SPSW) are currently being considered as a lateral load resisting system. A numerical method was proposed to have a comprehensive comparison of seismic behaviors of the plane wall (PW) and stiffened plane wall (SPW) with different stiffener characteristics, having the same weight, by using finite element modeling (FEM). The model was validated by using previously published experimental works. The material and geometric nonlinearity were taken into consideration. In this paper, the effect of using stiffeners with different cross-section shapes and directions will be studied, and key issues, such as load-carrying capacity, stiffness, and energy dissipation capacity, were discussed in depth. It was found that the proposed SPW with horizontal L, T, and U stiffeners could effectively improve load-carrying capacity by about 4, 20, and 23%, respectively. Diagonally and horizontally, SPWs with U stiffeners have higher energy-dissipation capacity than PW by about 57, 50%, respectively. This method provides a combination of high-performance stiffeners form and material for improving the seismic behavior of SPW.

Experimental Investigation of Axial Load and Detailing Effects on the Inelastic Response of Reinforced-Concrete Masonry Structural Walls with Boundary Elements

In typical wall load-bearing reinforced-masonry (RM) buildings, the lateral and vertical forces are resisted by rectangular shear walls. Thus, the walls are subjected to high vertical forces from gravity loads that are expected to limit the displacement and energy dissipation capacities. Moreover, the rectangular RM shear walls have limited lateral stability because of the single vertical reinforcement layer. The intent of this study is to investigate the inelastic cyclic response of RM structural walls subjected to axial compressive stress that results in precompression ratios, P/Agfm′, higher than 10%. The main objective is to propose practical component-level seismic detailing recommendations to enhance the overall structural performance. In this respect, three half-scale, fully grouted RM shear walls were tested under constant axial load, in-plane fully reversed cyclic loading, and top moment. The tested specimens are flexural dominant to simulate the response of mid and high-rise RM shear walls under strong seismic actions. The walls were designed to have enlarged boundary elements built using C-shaped blocks to evaluate the ability of end zone detailing and confinement to alleviate the impact of the high axial load. The test results demonstrated an overall enhanced structural performance for the three walls. The three specimens attained high ductility levels, high energy dissipation capacity, and failure in the ductile flexural mode. The presence of the well-detailed and confined boundary elements was effective in mitigating the impact of the high axial compression load. Thus, utilizing this type of masonry shear wall increases the competitiveness of masonry buildings as an alternative construction method.

Evaluation of approximate methods for estimating residual drift demands in BRBFs

Nowadays, Buckling Restrained Braced Frame (BRBF) system is extensively used for the seismic design of new buildings. This system is composed of Buckling Restrained Braces (BRBs) that do not buckle under compression forces, and have high energy-dissipation capacity. However, low post-yield stiffness of the brace core in BRBs may cause large residual drifts after the occurrence of an earthquake. In this study, four approximate methods for estimating residual drift demands in BRBFs are evaluated. These methods include the FEMA P-58 method, the method proposed in this study, the method proposed by Erochko et al. and the coefficients method introduced by Ruiz-García and Chora, calibrated in this study for BRBFs. To evaluate the estimated residual drifts of BRBFs according to these approximate methods, 2-, 4-, 6-, 8-, 10- and 12-story BRBFs are designed. Nonlinear dynamic analyses are performed on the BRBFs using 78 ground motion records scaled to different ground motion intensity levels. The results show that the proposed method is more accurate than the FEMA P-58 and Erochko et al. methods that are conservative for estimating the median and mean residual drifts of BRBFs, respectively. Moreover, the coefficients method, which estimates the median of maximum residual drifts, is the most accurate method among the four methods considered. However, it does not provide information about the height-wise distribution of residual drifts.

Optimum energy based seismic design of friction dampers in RC structures

Friction-based dampers are considered as one of the most efficient Energy Dissipation Devices (EDDs) due to their advantages such as adjustability and high energy dissipation capacity. However, their efficiency is strongly associated with the design slip load values along the structure. Conventional design methods using uniform slip load distributions may result in concentrating and localizing damage in certain storey levels. In this study, a practical energy-based optimization methodology is developed for seismic design of RC frame buildings with friction-based EDDs. The proposed method aims at improving the seismic performance of the structure by redistributing the slip loads of friction dampers to obtain a more uniform height-wise distribution of energy dissipation capacity. This leads to a design solution with maximum energy dissipation, and therefore minimum structural damage under a design earthquake. The low computational cost and efficiency of the proposed method is demonstrated through the optimum design of 3, 5, 10, 15 and 20-storey RC frames equipped with wall-type friction dampers under a set of synthetic spectrum-compatible earthquakes. The results show that after only a few steps the optimum design frames exhibit up to 31% and 70% less maximum inter-storey drift and global damage, respectively, compared to their conventionally designed counterparts.

Experimental study of hysteretic behavior of semi-rigid frame with a corrugated plate

Corrugated steel plate shear wall (CSPSW) is one of the new structural systems used to resist earthquakes and that has better a hysteretic behavior than a flat plate shear wall. In this paper, three full-scale, single-story, single-bay specimens, consisting of one semi-rigid frame without infill panels and two semi-rigid frames with unstiffened and stiffened doubly trapezoidal corrugated plates, were subjected to cyclic loading. The hysteretic behavior and energy dissipation capacity of the three specimens were compared. The experimental results revealed that the corrugated plate greatly enhanced the stiffness and lateral load-carrying capacity of the semi-rigid frames. Therefore, the frames with the corrugated plates had higher energy dissipation capacity than the frame without infill panels. Moreover, the strength, stiffness and energy dissipation capacity of the stiffened corrugated specimen were greater than those of the unstiffened corrugated specimen, although the ductility of the stiffened corrugated specimen was lower. A method of calculating the lateral capacity of CSPSWs was proposed based on the superposition principle. This method could accurately predict the lateral capacity of the corrugated specimens.

Tensile behavior of strain-hardening geopolymer composites (SHGC) under impact loading

Strain-hardening geopolymer composites (SHGC) exhibit remarkable ductility, crack control and high energy dissipation capacity when subject to quasi-static tensile loading. However, their mechanical performance under dynamic loading has not yet been explored. A comprehensive assessment of possible rate effects is required to facilitate a targeted material design for various practical applications. The article presents the results of an experimental investigation on the mechanical behavior of two types of SHGC under both quasi-static and impact tensile loading. The composites were reinforced with 2% of either short polyvinyl alcohol (PVA) fiber or ultra-high molecular-weight polyethylene (UHMWPE) fiber. The experiments were performed both at the composite scale and at the fiber level. The impact tests on the plain geopolymer matrix and SHGC were performed in a gravity-driven split-Hopkinson tension bar (SHTB) at strain rates of up to 300 s−1. The tests were accompanied by optical measurements to assess specimen deformation and multiple cracking by means of Digital Image Correlation (DIC). The dynamic fiber-matrix bond properties were investigated in a miniature split Hopkinson bar. Both under quasi-static tensile loading and impact tensile loading, the SHGC made with UHMWPE fibers exhibited superior mechanical performance compared to the composite made with PVA fibers. When comparing the impact tensile performance of SHGC with normal-strength SHCC from previous studies, SHGC demonstrated higher dynamic tensile strength and energy dissipation capacity, making SHGC promising for strengthening/prospective applications against highly dynamic actions.

Prior and post peaks compressive behavior of concrete-filled double-skin tubular columns with BFRP-punched-in outer steel and BFRP-circular inner steel

Fiber-reinforced polymer composites have been widely used to design fiber-reinforced polymer–based confined concrete columns with potential benefits. However, it is critical to design a column with sufficient post-peak performance that can prevent its collapse at the rupture of the fiber-reinforced polymer tube. This article presents the experimental results on the prior and post peaks behavior of concrete-filled double-skin tubular columns with basalt fiber-reinforced polymer (BFRP)–punched-in outer steel and BFRP-circular inner steel (BFST-DSTCs). Twenty-two specimens were tested under axial compression to investigate the effects of design parameters on the behavior of the BFST-DSTC. The outcomes reveal that the BFST-DSTC exhibits the best performance in terms of load capacity, confinement ratio, failure and damage mechanisms, and ductility in prior and post peaks. The inner fiber-reinforced polymer jacket delays the buckling of the inner tube. The punched-in patterns of the outer steel improve the confinement effectiveness of the fiber-reinforced polymer jacket. The BFST-DSTC displays a good post-peak performance with high-energy dissipation capacity that prevents the concerned structure from collapse after the fiber-reinforced polymer jacket rupture. Finally, a new confinement model is proposed to predict the ultimate point of the confined concrete.

Seismic performance of fire exposed steel welded WUF-W and RBS connections

Strength properties of structural steel are reduced when exposed to fire above temperature 600°C. A widely used general rule is that if the steel members in the building frame are reasonably straight with no visible distortion after a fire event, it can be reused. If these members are accepted for reuse with minor or no repairs, then the performance of steel members with a high-temperature fire exposure under a future earthquake event should be known. This study investigated the cyclic response of fire exposed steel Welded Unreinforced Flange Web (WUF-W) and Reduced Beam Section (RBS) welded connections. The results showed that fire exposed steel connections are vulnerable to earthquake loading if they are reused with minor or no repairs. When the performance of connections was compared, it was understood that the usage of RBS connection provides high safety, whereas WUF-W connection has the high moment capacity and energy dissipation capacity.

Finite element analyses on energy dissipation capacity of upper flange welded-lower flange bolted beam-column connection with slotted holes

ABSTRACT In steel structures, the greater energy dissipation capacity of a beam-column connection means greater seismic performance. Increasing energy dissipation of the slip of cantilever beam splices is an effective method of improving the energy dissipation capacity of beam-column connections. This paper provides a study of an “upper flange welded-lower flange bolted” (UWLB) beam-column connection with slotted holes. The UWLB connection is a new type of the beam-column connection, whose upper flanges and lower flanges of the splicing area have different splicing methods, the upper flanges welded while the lower flanges bolted. Six finite element models were established to analyze the effects of the different slotted hole dimensions on energy dissipation capacity. The results show that the energy dissipation of the splicing area increases with the increase of slotted hole dimensions, and the connections have greater rotational capacity. The energy dissipation ratio of the splicing area is more than 37.7%, the ratio increases with the increase of the slotted holes dimensions. The UWLB connections with slotted holes achieved 0.06 rad rotation under the cyclic loading. The UWLB connection with slotted holes has greater rotational capacity and higher energy dissipation capacity of the splicing area than the normal UWLB connection.

Application of slit link beam in eccentrically braced frames

Slit dampers are a specific type of metallic yielding dampers, for which many studies have been conducted in recent years, to investigate their behavior and possible applications in structures. In this paper, by considering the behavior of this type of dampers, the use of slit link beam in eccentrically braced frames is proposed. A slit link beam is a link beam in which the beam web is divided into a number of vertical links using slits/openings. The geometry of the links is designed to ensure uniform distribution of normal stress along them. Analytical equations are developed to predict the behavior of the slit link beam and the eccentrically braced frame. The behavior of the proposed system is studied using verified numerical analyses in Abaqus software. The “Ductile Damage” model is used to predict the failure in the numerical models. After verifying the numerical analysis, parametric studies are conducted on the eccentrically braced frames with slit link beams. In this regard, various geometric parameters of these frames are considered and their effects on the behavior of the proposed system are determined. Based on the results of this study, the proposed system has a high energy dissipation capacity, when the limitations of this study for the slit link beam geometry and the braced frame are observed. Consequently, a well-designed eccentrically braced frame with slit link beam can be used as an efficient lateral load resisting system and it can have advantages over the conventional link beam, when the link beam is long.

Theoretical and experimental behaviour of a hybrid semi-rigid glulam beam-to-column connection with top and seat angles

This article proposes to use the bolted top and seat angles to provide excellent moment resistance and high energy dissipation capacity for glulam beam-to-column connection. Angles are anchored on the glulam beam using the glued-in steel plate technology and connected to the column by anchorage bolts. A theoretical model is presented in this article to evaluate the moment-resistant properties of the connection based on the component method. To validate the accuracy of the theoretical model, several hybrid connections are tested under monotonic and reversed cyclic load. The test results showed that the proposed hybrid connection has a high rotational stiffness and excellent moment resistance. The theoretical results are also consistent with those of the experimental model.