Search

In this paper, a new type of structure was introduced. The spatial steel grid structure was composed of the top layer, lower layer H-shaped steel ribs and square steel tubes. The shear key is the key part of the structure.Based on the real dimensions of a practical prototype,two sets of full-scale shear key specimens were made, one of which has vertical stiffening ribs. The loading tests of two groups of specimens were carried out to simulate cases under pure shears and the experimental results were compared with the simulations from the finite element analysis. The effects of vertical stiffeners on failure modes, ultimate loads, strength-yield ratio and ductility of shear key were studied through experiments. By parametric analyses in the present article, relations of the stiffening plates width and thickness was recommended.

This manuscript investigates the amplification factors for the design of nonstructural components for the near-fault pulse-like ground motions. The amplification factors are computed for the primary structure of three hysteretic models and 81 near-fault pulse-like ground motions. The effects of earthquake magnitude, rupture distance, peak ground velocity (PGV), maximum incremental velocity (MIV), structural degrading behavior, ultimate ductility factor, μ u, and damping of nonstructural components, ξ c, are evaluated and discussed statistically. The results indicate that the near-fault pulse-like ground motions can significantly increase the amplification factors of nonstructural components with primary structure period. Ground motions with larger earthquake magnitude tend to induce greater amplification factors. The effect of PGV and MIV on amplification factors increase with the increase of primary structure damage. The near-fault pulse-like ground motions are more dangerous to components mounted on structures with strength and stiffness degrading behavior than ordinary ground motions. The damping of nonstructural components influences the amplification factors significantly in the short and fundamental period regions. A new simplified formulation is proposed for the application of the amplification factors for the design of nonstructural components for the near-fault pulse-like ground motions.

The last few decades have witnessed an increasing emphasis on the development of strain-based approach for predicting the creep life or damage of components operating at elevated temperatures. Creep ductility, as a key parameter in this approach, may vary with a number of factors including strain rate, state of stress, operating temperature, material microstructure, etc. The present paper, however, is focused on reviewing the state-of-the-art understanding of the effects of stress level and stress state on the creep ductility. Mechanisms involving the void growth and coalescence are presented to describe the role of stress level in the variation of uniaxial creep ductility. The prediction capacity of existing empirical ductility models is also assessed in light of uniaxial test data. On the other hand, a vast body of multiaxial creep test data, collected from open literature, is utilized to examine the influence of the state of stress on the creep ductility. Then, a variety of multiaxial ductility factor models are introduced and evaluated with the available experimental data. Finally, a brief discussion on the dependence of creep ductility on the stress triaxiality and Lode parameter, predicted by numerical methods, is provided.

The soft story located in the basement of tall buildings for parking or shopping lot. Considering the limitation in architecture, these structures may be retrofitted by implementing earthquake energy dissipation such as viscous damper devices in soft story level. Nevertheless, an extensive review of related literature indicates that the effect of viscous damper on response modification factor is not considered. Therefore, this study proposed the response modification factors for steel structures furnished with viscous damper devices in soft story level and investigated the effect of implementing such devices on the response modification factor. In this research, steel structures with numerous stories were considered to evaluate the response modification factor, which was formulated based on three aspects, namely, strength, ductility, and redundancy factors. Quasi-static nonlinear analysis was performed using finite element software based on structural models equipped with damper devices installed in different locations of the parking level. No open bay is available in other floors to install the damper devices. Meanwhile, the overstrength, ductility, and response modification factors were established by conducting pushover analysis. Results of the study revealed that the response modification factors for structures equipped with damper devices are higher than those of structures without damper devices. Moreover, the value of response modification factor was affected by the number of stories and number of dampers. Considering the analytical results for different cases, the equation for determining the response modification factor for steel structures furnished by viscous damper devices in soft story level was proposed.

The response modification factor (R) in IS1893 [5] is a significant parameter in the analysis of seismic design of structure by means of non-linear response of a structure. This paper enumerates on determining the actual values of R factor for RC special moment resisting frame by performing detailed non-linear static pushover analysis for various 2D framed structures of special moment resisting frames. A parametric study has been carried out by varying the time period up to 4 of the structure and zone factor and the corresponding R values are obtained, which primarily depends on three other factors. From the detailed analysis, a relationship between response reduction factor, Time period, Zone (Rμ-T-Z) has been proposed. The results show that the values of R, given in the codes are pessimistic and hence, an optimistic value shall be adopted based on the analytical results. As an application, the values arrived from the proposed relationship is then compared with the values obtained from the structures analyzed.

Joints are critical parts of structural members. In order to study the mechanical properties of beam-column joints improved by using UHPC after fire exposure, a series of tests have been conducted on reinforced concrete beam-column joints, with both conventional concrete and UHPC in the joint. Fire exposure tests were carried out on the specimens in the light of the designated heating curve, then followed by quasi-static loading tests. Measurements were respectively made on the temperature and load-displacement of the joints. Several significant parameters were analysed from the results of the loading tests, such as pinching width ratio, displacement ductility factor, energy dissipation, stiffness degradation and equivalent hysteretic damping ratio. The results show that high temperatures have a significant effect on the ultimate strength and initial stiffness of concrete beam-column joint specimens. The application of UHPC significantly improves the mechanical behaviour of beam-column joints. In addition, the energy-consuming capacity is enhanced. After fire exposure, the loading capacity of UHPC specimens is reduced correspondingly.

The behavior factor is used to reduce the elastic spectrum ordinate or the forces obtained from a linear analysis in order to take into account the non-linear structural properties. The more accurate this parameter is estimated, the more exact responses of the structures will be obtained. Recently, coupled walls with steel coupling beams are extensively utilized as an efficient system against lateral forces in high-rise buildings. But, there is not enough information about the behavior of these walls during earthquake, and design codes have not suggested any behavior factor for this structural system. Consequently, this paper is devoted to find the behavior factor of this structural system. To achieve this goal, six-, twelve- and twenty-story buildings are assessed. Except for the number of stories, all characteristicsof these buildings are completely similar. Buidlings’ height, the length of the coupling beams and the coupling ratio are key parameters which influence the behavior factor of the aforesaid structural system. In this work, the effect of these parameters on this factor are studied.

Present investigation consists in casting and testing six seismically detailed beam column reinforced concrete joints. All specimens were subjected to quasi-static monotonic loading. These damaged specimens were refurbished with two different configurations of carbon fiber-reinforced polymer laminates. Repaired specimens were again subjected to quasi-static monotonic loading. Results of investigation revealed that ultimate strength of configurations 1 and 2 was increased by 8.6, 6.7 % and ultimate deflection was increased by 54.6, 51.2 %, respectively. However, ductility factor, stiffness and ductility of repaired specimens were decreased by 24.8, 25.6; 60.6, 51.7; 49, 48 %, respectively.

In the moment frame subjected to earthquake loads, beam-column joint is structurally important for ductile behavior of a system. ACI Committee 352 proposed guidelines for designing beam-column joint details. The guidelines, however, need to be updated because of the lack of data regarding several factors that may improve the performance of joints. The purpose of this study is to investigate the seismic performance of reinforced concrete exterior joints with high-strength materials and unbonded tendons. Three specimens with different joint shear demand-to-strength ratios were constructed and tested, where headed bars were used to anchor the beam bars into the joint. All specimens showed satisfactory seismic behavior including moment strength of 1.3 times the nominal moment, ductile performance (ductility factor = at least 2.4), and sufficiently large dissipated energy.

A new type of compliant polymer concrete for runway repair is introduced in this paper. To enhance the compliance of epoxy-based polymer concrete, some epoxy resin was replaced with liquid-type silicone rubber or tire waste powder. To estimate the temperature dependency of the mechanical behavior of the compliant polymer concretes, mechanical tests were also carried out. It was found that tire waste powder was more efficient than the silicone rubber in terms of mechanical performance. The experimental work revealed the 72:20:08(T) specimen provided the highest ductility factor while keeping the compressive strength above the minimum required value (30 MPa).

The response modification factor is one of the seismic design parameters that determine the nonlinear performance of building structures during strong earthquakes. Most seismic design codes lead to reduced loads. Nevertheless, an extensive review of related literature indicates that the effect of viscous dampers on the response modification factor is no longer considered. In this study, the effect of implementing viscous damper devices in reinforced concrete structures on the response modification factor was investigated. Reinforced concrete structures with different stories were considered to evaluate the values of the response modification factors. A nonlinear statistic analysis was performed with finite element software. The values of the response modification factors were evaluated and formulated on the basis of three factors: strength, ductility, and redundancy. Results revealed that the response modification factors for reinforced concrete structures equipped with viscous damper devices are higher than those for structures without viscous damper devices. The number of damper devices and the height of buildings have significant effects on response modification factors. In view of the analytical results across different cases, we proposed an equation according to the values of damping coefficients to determine the response modification factors for reinforced concrete structures furnished with viscous damper devices.

The seismic behavior factor R (noted q in the european seismic design code, the Eurocode 8) of reinforced concrete frame structures is evaluated based on comparative analysis between non-linear static pushover and non-linear incremental dynamic analyses. For this purpose, three-, six-, and nine-storey reinforced concrete frame structures, considered as low-, medium-, and high-rise frame, respectively, were designed according to reinforced concrete code BAEL 91 and Algerian seismic code RPA 99/Version 2003. Non-linear static pushover analysis using inverted triangular loading pattern and incremental dynamic analysis using a set of seven time-history earthquake records were carried out to compute the R factor components, such as ductility and overstrength factors, with the consideration of failure criteria at both member and structural levels. The results obtained by non-linear static pushover and incremental dynamic analyses are compared. According to the analysis results, it is observed that in the case of non-linear static pushover analysis, the value of the seismic behavior factor decreases as the number of stories increases, whereas in the case of non-linear incremental dynamic analysis, the trend observed is not the same: the value of the seismic behavior factor increases as the number of stories increases. This result shows that the value of the seismic behavior factor depends, among others parameters, on the height of a structure, which parameter is not taken into account by the seismic design codes. In the light of the information obtained from incremental dynamic analyses, it is observed that the value of the seismic behavior factor adopted by the seismic design code RPA 99/Version 2003 is overestimated, especially for low-rise frame structure. This paper also provides conclusions and the limitations of this study.

According to current engineering practice, Confined Masonry (CM) buildings are weak in earthquake resistance and difficult in post-quake restoration. A new form of structure, i.e. Hybrid Masonry – Reinforced Concrete Structure (HMRCS), is investigated. By slightly increasing the sizes and reinforcement ratios of the RC members, i.e. beams and columns, which normally only act as confinement in a CM structure, now play an essential role in resisting the gravity load in HMRCS, while the masonry wall mainly resists the lateral earthquake load. To investigate the seismic-resistant behavior, pseudo-static tests on two full-scale HMRCS specimens were conducted, and the measured hysteretic curves were analyzed. Finite Element (FE) simulation was performed to verify the working mechanism and seismic response of the HMRCS specimens. The lateral displacement ductility factor obtained from the experimental results can fully satisfy the seismic requirement of structures. Therefore, HMRCS is reliable if its RC frame members and masonry walls are designed properly. Furthermore, the feasibility of using FE software to study the proposed HMRCS has been validated by comparing the experimental and simulation results.

Most current seismic design includes the nonlinear response of a structure through a response reduction factor (R). This allows the designer to use a linear elastic force-based approach while accounting for nonlinear behavior and deformation limits. In fact, the response reduction factor is used in modern seismic codes to scale down the elastic response of a structure. This study focuses on estimating the actual ‘R’ value for engineered design/construction of reinforced concrete (RC) buildings in Kathmandu valley. The ductility and overstrength of representative RC buildings in Kathmandu are investigated. Nonlinear pushover analysis was performed on structural models in order to evaluate the seismic performance of buildings. Twelve representative engineered irregular buildings with a variety of characteristics located in the Kathmandu valley were selected and studied. Furthermore, the effects of overstrength on the ductility factor, beam column capacity ratio on the building ductility, and load path on the response reduction factor, are examined. Finally, the results are further analyzed and compared with different structural parameters of the buildings.

This article presents a concise multiaxial creep-damage model for creep crack growth considering the cavity growth and microcrack interaction. Special emphasis is put on developing and validating the multiaxial creep ductility factor (MCDF) based on power-law creep controlled cavity growth theory. Good agreements with the theoretical and experimental data prove the effectiveness of the proposed MCDF. The application of the proposed creep-damage model through finite element simulation of the creep deformation and crack growth in C-Shaped Tension and Compact Tension specimens of 316H tested at 550 °C confirms the predictive capability of the proposed model.

This manuscript investigates the constant damage inelastic displacement ratios for the near-fault pulse-like ground motions. The inelastic displacement ratios are computed for three hysteretic models and 81 near-fault pulse-like ground motions. The effects of near-fault pulse-like ground motions, period normalization, earthquake magnitude, rupture distance, peak ground velocity (PGV), maximum incremental velocity (MIV), structural degrading behavior and ultimate ductility factor μu are evaluated and discussed statistically. The results indicate that the near-fault pulse-like ground motions can significantly increase the displacement demand of structures with medium period. The period normalization can clearly reduce the dispersion of inelastic displacement ratio. The effect of MIV on inelastic displacement ratios is more obvious than PGV. The near-fault pulse-like ground motions are more dangerous for structures with strength degrading behavior than ordinary ground motions. A predictive model is proposed for the application of constant damage inelastic displacement ratios for near-fault pulse-like ground motions.

Deem test results from the low reversed cyclic loading quasi-static test with 2 RC columns as the basic information of secant stiffness damage of the reference column and take use of the TMS instrument in the test to artificially make the damage percentage of secant stiffness of the RC column as 33%, 50% and 66%, 6 damaged columns in total; reinforce the 6 damaged columns and 2 undamaged ones under the same conditions with AFL, through quasi-static contrast test. Test results show that it is able to effectively boost horizontal ultimate bearing capacity and ductility deformability of the RC columns with AFL for reinforcement; besides, there is a linear function relationship between horizontal ultimate bearing capacity, target ductility factor, and damage percentage of secant stiffness.

The objective of this study is to introduce a procedure for determining the hysteretic energy demand for self-centering single-degree-of-freedom (SDOF) systems with typical flag-shaped hysteretic models considering the influences of the structural characteristics. Based on nonlinear dynamic time history analyses using a series of representative earthquake records that have been carefully selected, the relationship between the hysteretic energy demand and structural parameters is investigated. Subsequently, the spectra of the ratio of the hysteretic energy EH to the input energy EI, denoted as the EH/EI spectra, are proposed. The results indicate that ground motion types have little influence on the EH/EI spectra. However, both structural features, including energy ratio, damping ratio, and ductility factor, and the initial period of systems, play a significant role in the determination of the EH/EI spectra. The proposed approach can be used to predict the hysteretic energy demand for self-centering SDOF systems.

In highly elevated piers and long span beams, a hollow section is often used to reduce the self-weight and increase the flexural rigidity of members. Numerical analysis was conducted to obtain the moment-curvature curves and curvature ductility factor for the RC hollow section beams under a range of hollow portion sizes and reinforcement conditions in the upper flange and web. The curvature ductility factor was constantly maintained until the hollow portion size(bi/bo/ hi/ho) was less than or equal to 0.5. The curvature ductility factor decreased sharply if (bi/bo/ hi/ho) was 0.7 or more. The curvature ductility factor of the beam decreased if reinforcement was provided in the web of the RC hollow section beam. To obtain the same level of the ductility factor as the singly reinforced section, the reinforcement should be provided in the upper flange as much as the web reinforcement.

The characteristic strength properties of structural glulam connections assembled with self-tapping screws were examined following the ASTM testing procedure in the study. Four screw types with various numbers were designated at each connection of the beam–girder structure with different nailing schedules. The results indicated that the maximum load capacity and dissipated energy of a connection fastened with 10-mm self-tapping screws were higher than those with 8-mm screws. And, the screws with both double-threaded sections and fully threaded shanks were higher than those of single-threaded screws. An improvement on the initial stiffness of a connection was found when the number of self-tapping screws increased. The connections assembled with the toe-nailing approach from the beam’s bottom surface provided higher maximum loading capacity, medium initial stiffness, and a larger ductility factor, resulting in higher dissipated energy with less fragile failure. The derived allowable loading values for a beam–girder connection fastened with self-tapping screws using the face-nailing approach were close to the code values for bolted and pinned connections. And, a toe-nailing approach provided higher allowable loads for connections than using a face-nail approach.

This paper mainly studies small hollow concrete block wall sets a certain level of reinforcement, vertical bar, core column and high aspect ratio, vertical and horizontal load, changes in load point height wall by shear form and bending failure pattern changes and shear capacity and flexural capacity. Nonlinear analysis simulation using ANSYS finite element analysis software of the specimen, mainly analysis and predict the failure modes of the different loading conditions wall. Obtained by calculating the failure pattern of the specimen, the load-displacement curve, the various stages of the load-displacement values and calculated the relative deformation and ductility factor of the wall under various loading height. Comparative analysis of the load-displacement curve variation of the shear failure and bending failure form, draw the conclusion that bending failure energy consumption better performance.

Standard metal ductility factors are elongation and necking. These factors are defined as conditional ones in contrast to true (logarithmic) ductility factors. In addition, elongation and necking do not appear in an explicit form in the design formulas for the determination of static, cyclic or dynamic strength values.At the same time, exact values of ductility factors should be integrated into com-bined workability criteria for steels and alloys together with strength factors due to the unity of the processes of deformation and resistance to deformation. This combination of ductility factors and strength factors appears in a well-known formula describing dependence between the ultimate breaking strength and hardness.Here, the proportionality factor is equal to 0.3–0.6, and it is not characterized by the corresponding values of elongation or necking. Hence, the intention is to express the above-mentioned proportionality factor in a different form in respect of ductility characteristics, and, as a result, new ductility factors are proposed.Dependencies between ductility factors and yield limits, identified by the co-authors, may be applied to identify the synergetic criteria of metal materials to be used in the process of design, production and operation of welded metal structures. Moreover, the findings of the co-authors may be used in the process of design, production and operation of working elements of construction machines and equipment.Стандартными показателями пластичности металлов являются относительное удлинение δ и относительное поперечное сужение Ψ. Эти величины по определению считаются условными в отличие от истинных (логарифмических) характеристик пластичности. Кроме того, относительные удлинение и сужение не входят в явном виде в расчетные формулы по определению статической, циклической или динамической прочности. Вместе с тем, именно показатели пластичности должны присутствовать в комплексных критериях работоспособности сталей и сплавов на- ряду с показателями прочности, в силу двуединства процесса деформирования и сопротивления его протеканию. Такое сочетание показателей пластичности и прочности усматривается в широко известной зависимости временного сопротивления разрыву от твердости. Коэффициент пропорциональности этой взаимосвязи, принимающий значения 0,3…0,6, не характеризуется соответствующими значениями δ или Ψ. Отсюда возникает намерение выражать указанный коэффициент пропорциональности в иной форме характеристик пластичности. Предлагаются коэффициенты пластичности вида K = (1 – δ) и K = (1 – Ψ) , взаимосвязанные выражением K = K /(1 + K ). При известном временном сопротивлении σ посредством коэффициентов удлинения K и сужения K определяются истинное сопротивлениеразрыву S = σ / K предел выносливости σ = K S и предел текучести. Для стальных поковок категорий прочности КП175—КП315 можно принять зависимость σ = σ K , для категорий прочности КП345—КП440 σ = σ / (1+ K ) , для КП490—Т КП785 σ = σ /(1+ K ).

This paper summarizes the comprehensive statistical results of constant damage inelastic displacement ratios which allow the evaluation of maximum inelastic displacement demand for structures with constant damage performance. The inelastic displacement ratios are calculated with modified Park-Ang damage index and inelastic single-degree-of-freedom systems subjected to 573 ground motions. The influences of period of vibration, levels of damage, site conditions, earthquake magnitude, rupture distance, post-yield stiffness, stiffness degradation, strength deterioration, parameter β and ultimate ductility factor μ u in damage index model are evaluated and discussed statistically. It is found that the effect of site conditions is not very significant. Specifically, coefficients of variation are approximately period-independent and site-independent. The degrading systems with short period of vibration would experience larger inelastic displacement than non-degrading systems. The effects of parameter β and ultimate ductility factor μ u are moderate in short period region. A simplified expression is proposed for the application of constant damage inelastic displacement ratios.

This paper presents the influence of incident angles of earthquakes on inelastic dynamic responses of asymmetry single story buildings under seismic ground motions. The dynamic responses such as internal forces and rotational ductility factor are used to evaluate the importance of the incident angles of ground motions in the inelastic range of structural behavior. The base shear and torque (BST) response histories of the resisting elements and of the building are used to prove that the shape of the BST surface of the building can be a practical tool to represent those of all resisting elements. This paper also shows that the different global forces which produce the maximum demands in the resisting elements tend to converge toward a single distribution in a definable intensity range, and this single distribution is related to the resistance distribution of the building.

Characteristics of creep deformation for austenitic stainless steel foils are examined using the modified Monkman–Grant equation. A series of creep tests are conducted on AISI 347 steel foils at 700 °C and different stress levels ranging from 54 to 221 MPa. Results showed that at lower stress levels below 110 MPa, the creep life parameters e min , e r , t r can be expressed using the modified Monkman–Grant equation with exponent m′= 0.513. This indicates significant deviation of the creep behavior from the first order reaction kinetics theory for creep (m′ = 1.0). The true tertiary creep damage in AISI 347 steel foil begins after 65.9% of the creep life of the foil has elapsed at stress levels above 150 MPa. At this high stress levels, Monkman–Grant ductility factor λ ′ saturates to a value of 1.3 with dislocation-controlled deformation mechanisms operating. At low stress levels, λ ′ increases drastically ( λ ′ = 190 at 54 MPa) when slow diffusion-controlled creep is dominant.

Response modification factor is one of the seismic design parameters to consider nonlinear performance of building structures during strong earthquake. Relying on this, many seismic design codes led to reduce loads. The present paper tries to evaluate the response modification factors of buckling restrained braced frames (BRBFs) utilized for rehabilitation of steel frames. Since, the response modification factor depends on ductility and overstrength, the static nonlinear analysis has been performed on building models including single and double bracing bays, multi-floors and different brace configurations (chevron V, invert V). The BRBFs values for factors such as ductility, overstrength, force reduction due to ductility and response modification have been assessed for all the buildings. The results showed that the response modification factors for BRBFs have high values. It was found that the number of bracing bays and height of buildings have had greater effect on the response modification factors.

12 RC columns were made, including nine RC columns wrapped with BFRP, three RC columns without any reinforcement, to conduct the comparative study of axial compression. The result shows that the bearing capacity of the RC columns reinforced with the fibers increases obviously.The displacement ductility factor increases, but its increase rate becomes slow with increasing layers of fiber cloth, so the most economical layer number is 3. Based on the confinement mechanism of FRP cloth and the calculation formula of the bearing capacity for common RC column, the formula of the bearing capacity for reinforced RC column with BFRP cloth is proposed. The result of calculation basically tallies with the number in experiment.

The current paper tries to evaluate overstrength, ductility and response modification factors in special moment resisting frames with TADAS (triangular-plate added damping and stiffness) devices. For that matter, multi-story buildings were considered during the course of study. Further, OpenSees Software was applied to perform the static pushover analysis, the nonlinear incremental dynamic analysis as well as the linear dynamic analysis. In this research, seismic response modification factor for special moment resisting frames (SMRFs) with TADAS devices (T-SMRFs) and without them has been determined separately. The results showed that the response modification factors for T-SMRFs were higher than the SMRFs ones. It was also found that the number of stories of buildings has had greater effect on the response modification factors.

Through orthogonal test, the main influencing factors to the ultimate bearing capacity, ductility and energy consuming ability of L-shaped concrete-filled rectangular composite steel tubular columns are studied. Research results show as follows: the most important factor in deciding the ultimate bearing capacity is the steel tube wall thickness; the most important factor in deciding the ductility factor is the steel tube wall thickness; the most important factor in deciding the equivalent viscous damping coefficient is the strength classes of concrete. At the same time the best level combination of these factors are got.

SUMMARY In this paper, the seismic behavior of dual structural systems in forms of steel moment-resisting frames accompanied with reinforced concrete shear walls and steel moment-resisting frames accompanied with concentrically braced frames, have been studied. The nonlinear behavior of the mentioned structural systems has been evaluated as, in earthquakes, structures usually enter into an inelastic behavior stage and, hence, the applied energy to the structures will be dissipated. As a result, some parameters such as ductility factor of structure (μ), over-strength factor (Rs) and response modification factor (R) for the mentioned structures have been under assessment. To achieve these objectives, 30-story buildings containing such structural systems were used to perform the pushover analyses having different load patterns. Analytical results show that the steel moment-resisting frames accompanied with reinforced concrete shear walls system has higher ductility and response modification factor than the other one, and so, it is observed to achieve suitable seismic performance; using the first system can have more advantages than the second one. Copyright © 2011 John Wiley & Sons, Ltd.

Nonlinear static analysis procedures are key tools in evaluating the performance of existing buildings and verifying the design of seismic retrofits in seismically active regions. In this procedure, nonlinear force-displacement or moment-curvature (M-φ) behavior needs to be defined. In the ATC-40 document, values of M-φ have been proposed to model elements in a nonlinear procedure. However, these values need to be investigated to determine if they are representative of actual values. In this paper, an attempt has been made to numerically derive M-φ curves to simulate actual performance. Then, these curves are compared with the ATC-40 recommended curves with respect to various parameters. The study indicated that ATC-40 suggested values are conservative in nature in most situations.

2008 Wenchuan earthquake has showed that failure of masonry walls is one of the major causes of material damage and loss of human life due to seismic events. Therefore, study of masonry walls seismic behavior and development of effective and practical retrofitting schemes is an urgent need. So this work presents an experimental program that investigates in-plane seismic behavior of common types of shale masonry walls before and after retrofitting using epoxy resin injection technique. In this experimental study, the primary objective was to evaluate the efficiency of this retrofitting method on masonry walls. The results of this study shows that using epoxy resin injection technique increased the in-plane maximum strength, the ductility, the initial stiffness value, the stiffness, and the energy dissipated during all the loading stages, and decreased the ductility factor.

：Twenty-one RC columns were made, including nine RC columns wrapped with BFRP, nine RC columns wrapped with CFRP, three RC columns without any reinforcement, to conduct the comparative study of axial compression. The result shows that the bearing capacity of the RC columns reinforced with the fibers increases obviously. The bearing capacity of the RC columns with CFRP is higher than that with BFRP, but the difference is not obvious. The displacement ductility factor increases, but its increase rate becomes slow with increasing layers of fiber cloth, so the most economical layer number is 3. Based on the confinement mechanism of FRP cloth and the calculation formula of the bearing capacity for common RC column, the formula of the bearing capacity for reinforced RC column with BFRP cloth is proposed. The result of calculation basically tallies with the number in experiment.

To better solve the problems of local buckling and stability of thin-walled concrete-filled steel tubular short columns and improve the ability of specimens’ overall deformation, long or short binding rebars were set up and anchored on the inner surfaces of the steel tubes; meanwhile the static load test was performed. The results show that the main factors affecting the bearing capacity are steel pipe wall thickness, concrete strength, binding rebars in turn and the ductility is concrete strength, binding rebars, wall thickness. Long or short rebars also significantly improve the deformation properties of specimens. Taking the common specimens’ average ductility factor of 2.30 as a benchmark, the average factor of specimens configured with short rebars is 2.85, increased by 24% and configured with the long is 3.34, increased by 45%. Deformation properties of the specimens substantially increase and security of the structure enhances after setting up rebars.

This paper investigates the applicability of global ductility in the conventional design procedure of structure–foundation systems under earthquake excitation. For a bilinear elastoplastic model, an equivalent ductility factor for the combined structure and foundation is derived, which can be used in conjunction with the enlarged period and increased damping due to soil–structure interaction (SSI) to determine the design strength. A geometric transformation rule for predicting the ductility demand developed in the structure alone from that experienced by the interacting system is also derived, without the need of computing the rigid-body motion of the foundation. To validate this practical approach for assessing both inelastic strengths as well as ductility demands, a number of numerical results for different system parameters and earthquake excitations are provided. The effects of principal parameters involved are also examined.

For resolving the practical problem about bridge structures, according to the seismic damage regularity and the structural characteristics, the capacity design method of bridge structure was introduced. In order to account synthetically for the influence factors and convert the inelastic seismic design method into the pseudo-static method, which is easily accepted by engineers, the strength reduction factor was commonly used in seismic design of structures. Based on the principles of the inelastic spectrum established by using the relationship between the strength reduction factor R and ductility factor μ, the seismic demand spectra were obtained from the design spectrum of the Highway Engineering Seismic Design Code (JTJ 004-89). This will be beneficial to the earthquake-resistant capacity design in practical bridge structures.

This article (Part-II) continues the work of a previous article (Part-I). It undertakes a theoretical analysis of the curvature ductility factor (CDF) of a singly reinforced CRC (crumb rubber concrete) beam and demonstrates how CRC’s material ductility is transformed into structural ductility of a reinforced CRC beam. The result shows that CDF for a reinforced CRC beam is much higher than that for a conventional concrete reinforced beam.

Seismic performance of corner joints without seismic details was analyzed by software ABAQUS, the results indicated that the reinforcement ration of the girders has great effects on the failure process and seismic behavior of corner joints. Beam Haunch Method was used to strengthen these joints, and then finite element analysis was conducted for the joints with unidirectional haunched beam (UHB)and bidirectional haunched beams(BHB). It was found that the bearing capacity of joints was significantly improved but the ultimate displacement and ductility factor were slightly affected by the haunch strengthening. The strengthening effect of bidirectional haunch was obviously superior to that of unidirectional haunch.

This study evaluated the effect of vibration, level of lateral yielding strength, site conditions, ductility factor, strain-hardening ratio, and post-capping ratio of the strength limited bilinear SDF systems on the inelastic displacement ratio. The nonlinear response history analysis was conducted using 240 ground motions which were collected at the sites classified as site classes B, C, and D according to the NEHRP. To account for the P- effects, this study considered negative stiffness ratios ranging from -0.1 to -0.5 of elastic stiffness. Four different damping ratios are used: 2, 5, 10, and 20%. From this study, an equation of inelastic displacement ratio was proposed using nonlinear regression analysis.

A methodology for assessing the seismic capacity of existing frames in terms of energy is proposed. It estimates the global amount of input energy—in form of a factor AE IU —and hysteretic energy that the overall structure can dissipate until collapse under earthquake-type loadings. The method requires static pushover analyses to determine the ductility factor and energy shape of an equivalent single-degree-of-freedom system for the first—two or more—modes. The procedure accounts for the relation between the frequency content of the earthquake expected at the site and the dynamic properties of the existing structure. It can be useful for evaluating the possible deficit on energy dissipation capacity of existing structures, and for designing seismic retrofit solutions. Finally, the methodology is applied to reinforced concrete frames with wide beam-column connections representative of existing post-1970 buildings located in the earthquake-prone southern part of Spain.

The present study aims at investigating the cyclic flexural behavior of reinforced concrete beams with varying depths. Five reinforced concrete beams with beam depth ranging from 250 mm to 750 mm were tested under reversed cyclic loading and the influence of beam depth on the flexural strength and ductility of reinforced concrete beams was investigated. In addition, OpenSees was used to model the test specimens and the analytical results were compared with the experimental reuslts. It is shown that there is no apparent size effect on the normalized ultimate flexural strength of the tested beams, while for the displacement ductility factor, a significant size effect is observed. Load-deflection hysteric curves of test specimens obtained by the fiber-based element of OpenSees with Concrete03 and Hysteric models are in good agreement with those from experimental tests.