High-strength Concrete Frame Research Articles

Assessing potential damage and energy dissipation in low-rise high-strength concrete frames with strong infill walls using applied element method

Assessing potential damage and energy dissipation in low-rise high-strength concrete frames with strong infill walls using applied element method

Numerical modeling of weak infills with a central opening in high-strength concrete frames under pseudo-static loading using applied element method

Numerical modeling of weak infills with a central opening in high-strength concrete frames under pseudo-static loading using applied element method

Seismic behavior of precast 100 MPa grade HSC frames under reversed cyclic loading

This paper concerns characterizing the seismic behavior of precast high-strength concrete (HSC) frames. A half-scale, two-story, and two-bay precast HSC frame and a corresponding cast-in-place (CIP) frame were designed, constructed, and tested under reversed cyclic loading according to a prescribed history. The precast HSC frame consisted of precast column, composite beam, and CIP beam-column connection. HSC used had a nominal compressive strength of 100 MPa. Results demonstrate that both frames failed by crushing of concrete at the column bases, exhibiting a mixed sidesway failure mechanism. The hysteresis curves of both frames are arch-shaped without an evident pinching effect, and the energy dissipation capacity of two test frames is close. Also, the precast HSC frame and CIP frame show similar load-carrying capacity, with a difference of less than 1%. Global displacement ductility of the precast HSC frame is 3.75, which increases by 20.9% than that of the CIP frame. Moreover, a degenerated four-linear restoring forcing model for CIP and precast 100 MPa grade HSC frames is proposed.

Cyclic behavior of damage-controllable steel fiber reinforced high-strength concrete reduced-scale frame structures

To obtain desirable damage-controllable frame structures, three 1/3-scale, 2-bay, 2-story steel fiber reinforced high-strength concrete frames with high-strength steel rebars were fabricated and tested under combined axial load and cyclic lateral load. Under the principle of equal strength design, three types of columns with different arrangements of longitudinal rebars were designed (i.e., the first only reinforced with HRB 600 MPa high-strength steel rebars, the second reinforced with hybrid HRB 600 MPa high-strength and 1200 MPa ultra-high-strength (UHS) steel rebars, and the third only reinforced with UHS steel rebars), while the beams were generally reinforced with HRB 600 MPa steel bars. The test results reveal that all frames exhibited comparative seismic performance and represented acceptable residual deformation before a lateral drift of 3%, which can be a promising alternative to traditional frames. Incorporating UHS rebars in frame columns could make the inter-story displacement distribution relatively uniform, which would avoid the damage concentration in the bottom floor and the collapse of the structure. Compared to the frame merely with HRB 600 MPa rebars in the column, the frames with UHS rebars showed a positive lateral stiffness in a considerable deformation range after the formation of the plastic hinge in the beam, and the residual displacement and residual crack width were effectively controlled. The proposed ideal load-deformation behavior of the damage-controllable frame can clearly reflect the failure mechanism of the structure, and the secondary stiffness ratios of different stages can be obtained to accurately evaluate the damage control performance of the structure at different stages.

Seismic Damage Model of High-Strength Reinforced Concrete Frame Columns

In this paper, several existing seismic damage models as well as their characteristics were discussed first of all. And then it was figured out that variational history of incremental dissipated hysteretic energy of tentative frame columns under different loading cycle levels; the influence of axial compression ratio, type of stirrups, stirrup ratio, reinforcement ratio, strength grade of concrete and shear span ration on the incremental dissipated hysteretic energy was discussed and analysed. The damage index of tentative frame columns was compared and analysed according to the existing seismic damage models, and the seismic damage models adapt to high-strength concrete columns and ordinary-strength concrete columns were offered. The influence of shear span ration, axial compression ratio and stirrup ratio on the damage was discussed and analysed according to the variational history of the damage index under different loading cycle levels. Lastly through analysing all sorts of seismic damage models comparatively, the seismic damage model of high strength concrete frame columns is put forward, which offers good basement for further damage analysis.

Seismic response assessment of high-strength concrete frames strengthened with carbon fiber reinforced polymers

In recent years, the use of new materials and technologies with the aim of developing high-performing and costeffective structures has greatly increased. Application of high-strength concrete (HSC) has been found effective in reducing the dimensions of frame members; nonetheless, such reduction in dimensions of structural elements in the most cases may result in the lack of accountability in the tolerable drift capacity. On this basis, strengthening of frame members using fiber reinforced polymers (FRPs) may be deemed as an appropriate remedy to address this issue, which albeit requires comprehensive and systematic investigations. In this paper, the performance of properly-designed, two-dimensional frames made of high-strength concrete and strengthened with Carbon Fiber Reinforced Polymers (CFRPs) is investigated through detailed numerical simulation. To this end, nonlinear dynamic time history analyses have been performed using the Seismosoft software through application of five scaled earthquake ground motion records. Unstrengthened (bare) and strengthened frames have been analyzed under seismic loading for performance assessment and comparison purposes. The results and findings of this study show that use of CFRP can be quite effective in seismic response improvement of high-strength-concrete structures.

Dynamic analysis of high-strength concrete frame buildings for progressive collapse

The issue of progressive collapse of two real-scale frame buildings examples (three and six stories) constructed from High-Strength Concrete (HSC with fc` =75 MPa) and Normal-Strength Concrete (NSC with fc` =32 MPa) under central column removal have been studied using numerical analysis. Initially, a finite element linear static analysis was carried out. Next, linear dynamic and non-linear dynamic analyses were conducted to account for the extreme dynamic effects that arise during central column removal. The values of Demand-Capacity Ratios are considered in each analysis. The results showed that, the analysis of progressive collapse under central column removal of three and six stories frame buildings constructed from HSC is approximately similar to that of the same structures constructed with NSC. The three stories building constructed from NSC and HSC would not be susceptible to collapse for linear statically central column removal, while the situation is reversed for both NSC and HSC six stories buildings. NSC and HSC three and six stories buildings would be susceptible to progressive collapse for linear and nonlinear dynamic central column removal. The ratio between the maximum nonlinear dynamic displacement and the maximum linear dynamic displacement for NSC and HSC three stories buildings at the column removal are 1.17 and 1.18, respectively, whereas these ratios become 1.89 and 1.86 for NSC and HSC six stories building, respectively. The internal forces at the most critical sections for NSC and HSC three story building in the case of linear dynamic analysis are larger than that of linear static analysis by about 58% and 39%, respectively, while for six story building these ratios become 82% and 80%, respectively. For the case of nonlinear dynamic analysis, these ratios for NSC and HSC three story building are larger than that of linear dynamic analysis by about 9% and 7%, respectively, while for six story building these ratios become 11 % and 8%, respectively due to activation of plastic hinges.

Research on seismic behavior and shear strength of SRHC frame columns

The seismic behavior of steel reinforced high strength and high performance concrete (SRHC) frame columns was investigated through pseudo-static experiments of 16 frame columns with various shear span ratios, axial compression ratios, concrete strengths, steel ratios and stirrup ratios. Three kinds of failure mechanisms are presented and the characteristics of experimental hysteretic curves and skeleton curves with different design parameters are discussed. The columns’ ductility and energy dissipation were quantitatively evaluated based on seismic resistance. The research results indicate that SRHC frame columns can withstand extreme bearing capacity, but the abilities of ductility and energy dissipation are inferior because of SRHC’s natural brittleness. As a result, the axial load ratio should be restricted and some construction measures adopted, such as increasing the stirrup ratio. This research established effect factors on the bearing capacity of SPHC columns. Finally, an algorithm for obtaining ultimate bearing capacity using the flexural failure mode is established based on a modified plane-section assumption. The authors also established equations to determine shearing baroclinic failure and shear bond failure based on the accumulation of the axial load force distribution ratio. The calculated results of shear bearing capacity for different failure modes were in good agreement with the experimental results.

Detection and prediction of seismic damage to a high-strength concrete moment resisting frame structure

This paper describes a unique research program on the behavior, damage prediction and detection of a full-size, two-storey, high-performance concrete building subjected to a series of earthquake excitations. Repeated pseudo-dynamic tests were carried out on the structure during which increasing seismic forces were applied, with resulting greater levels of permanent damage to the structure. In order to monitor the level of damage, forced-vibration tests were carried out after each pseudo-dynamic test and were used to track changes in the building’s key dynamic properties. This combination of tests is applied for the first time on a full-size, high-strength concrete frame structure with recent seismic detailing. The paper presents the design of the test structure, the series of forced vibration and pseudo-dynamic tests, and the evaluation of building damage. To validate the procedure, identified stiffness reductions are related to quantities measured during pseudo-dynamic tests and to observed damage. A novel model updating procedure, including regularization, is applied to the structure and is shown to accurately predict the location of the increasing damage in the building.

Damage Analysis and Evaluation of High Strength Concrete Frame Based on Deformation-Energy Damage Model

A new method of characterizing the damage of high strength concrete structures is presented, which is based on the deformation energy double parameters damage model and incorporates both of the main forms of damage by earthquakes: first time damage beyond destruction and energy consumption. Firstly, test data of high strength reinforced concrete (RC) columns were evaluated. Then, the relationship between stiffness degradation, strength degradation, and ductility performance was obtained. And an expression for damage in terms of model parameters was determined, as well as the critical input data for the restoring force model to be used in analytical damage evaluation. Experimentally, the unloading stiffness was found to be related to the cycle number. Then, a correction for this changing was applied to better describe the unloading phenomenon and compensate for the shortcomings of structure elastic-plastic time history analysis. The above algorithm was embedded into an IDARC program. Finally, a case study of high strength RC multistory frames was presented. Under various seismic wave inputs, the structural damages were predicted. The damage model and correction algorithm of stiffness unloading were proved to be suitable and applicable in engineering design and damage evaluation of a high strength concrete structure.

The Strain Change Rules of Full-Scale High Strength Concrete Frame Columns with High Axial Compression Rations

Based on experimental study of 9 full-scale high-strength concrete(HSC) rectangular frame columns with high axial compression ratios, high-strength longitudinal reinforcements and transverse reinforcements and rectangular interlocking ties, their strain change rules of longitudinal reinforcement, stirrups and concrete were discussed and analyzed. The main results indicate as follows. The maximum tensile strain of longitudinal reinforcement decrease and the tensile strain of concrete increase quickly as the axial compression ratios and the strength grades of concrete are higher; the strains of outer stirrups are all the time greater than those of inner stirrups; the single brace stirrups have the same action with the closed stirrups.

Study on Resilience Model of High-Strength Concrete Frame Columns

Based on the horizontaldisplacements and loads of column at top end deduced according to sectionalbalanceable conditions at yield of high-strength frame columns, the lateralmaximum loads of column at top end calculated according to the Chinese currentconcrete code and involved regressive formulas, the resilience model ofhigh-strength concrete frame columns were established. The main results show:the resilience models of high-strength concrete frame columns proposed in thispaper consider influenced multi-facts and conveniently applied to engineering.

Behavior and ductility of high strength reinforced concrete frames

This paper presents an experimental study for the behavior and ductility of H.S.R.C frames. The experimental program was conducted on five specimens (frames). F1 is a control specimen consisting of beam with cross section 12×20cm and length 1.85m and two columns with cross section 12×20cm and height 1.5m. In the second specimen (F2) the depth of beam is changed from 20cm to 30cm but in the third specimen (F3) the dimensions of columns are changed to 12×30cm while in the fourth specimen (F4) the aspect ratio h/L (height to length of panel) of frame is changed from 0.81 to 0.625. The fifth specimen (F5) has different details of connections between columns and beam. The stirrups are arranged in half spacing distance at connection with respect to the regular distance of all columns and beams. The dimension of frames is selected to represent half scale frames and tested under cyclic loading. All specimens of the experimental program are tested in the reinforced concrete testing laboratory at Housing and Building National Research Center in Cairo.The results of the tests and the analysis of the obtained results are represented in different ways. The ductility factor (R) of high strength concrete frames for frames F1, F2, F3, F4 and F5 is 8.96, 7.48, 5.59, 6.24 and 8.87 respectively.

超環境オフィスビルの外観を形成する高強度コンクリート躯体─清水建設（株）新本社の概要─

2012年5月に竣工した清水建設（株）新本社は，省エネと快適性の両立，非常時の事業継続性（BCP）に注力した「超環境オフィス」である。本建物の外観を形成するのは，アルミキャストで覆われたPCフレームと本実（ほんざね）型枠を用いた打放し仕様の門形柱であり，いずれも新たなものづくりを追求した高強度コンクリート躯体である。これらの独創的な躯体は，意匠，構造から施工までの設計・技術者の有機的な連携と様々な性能検証によって実現した。

The Seismic Behavior of High-Strength Concrete Frame Joints

By studying the two high-strength concrete frame joints by means of experimental investigate and finite element analysis with the low cycle reversed loading method, it discussed the influence of the steel fiber on the seismic behavior of the high-strength frame joints. The result shows that, mixed with steel fiber can enhance the constraint of the concrete at the joint core area, improve the seismic behavior. Amount of steel fiber can replace part of the stirrup.

Shear Capacity Analysis of SRHSC Frame Joints

Based on the tests of 5 steel reinforced high strength concrete (SRHSC) frame interior joint specimens, this paper discusses the mechanism of load transference in the joints. Shear effect of each part of the joints including concrete, steel web, band, flange frame and stirrup is analyzed. And then, the shear capacity equation of SRHSC frame joints is presented. Comparing the calculation results with the test results, it is indicated that the shear capacity equation proposed can correctly evaluate the ultimate shear strength for SRHSC joints.

Experimental Study and Finite Element Analysis of the Seismic Behaviors for Steel Fiber Reinforced High-Strength Concrete Frame Exterior Joints

Based on the experimental results of three steel fiber reinforced high-strength concrete frame exterior joint under the low cycle loading, the numerical simulation by nonlinear finite element method was adopted to analyze their behaviors and to explore the influence of axial compressive ratio on seismic capacity of the joint. The results indicate that the increase of the axial compressive ratio enhances the restriction role to the joint core area concrete, slows down the degeneration degree of shearing-resistance capacity and stiffness, enhances the shearing-resistance capacity of the core area, the joint ductility and the energy dissipation capacity. The finite element analysis coincides well with the experimental results. In finite element analysis, steel fiber was equated with micro-reinforcement, and then put evenly into the concrete unit. Compared with the test results, the method of taking the steel fiber and concrete as a holistic model was thus validated.

Study on seismic damage of SRHSC frame columns

The damage evolution in steel reinforced high strength concrete (SRHSC) frame columns was studied based on the test results of cyclic reversed loading experiment of 12 frame column specimens with various axial compression rations, stirrups ratios, steel rations and loading histories. The variation law of the ultimate bearing capacity, ultimate deformation and ultimate hysteretic energy dissipation of specimens under different loading protocols was obtained. The seismic damage characteristics, as well as strength and stiffness degradation, of SRHSC frame columns were analyzed. Based on the analysis of the nonlinear double parameters combination of deformation and energy, a damage model that can well reflect the mechanical characteristics of members subjected to a horizontal earthquake action was established by considering the effects of the number of the loading cycles on the ultimate resistance capacity (ultimate deformation and ultimate energy dissipation capacity) of members, and the loading history on damage, etc. According to the test results, the related parameters of the damage model were proposed. Finally, the damage model proposed was validated by the test results. Results indicated that the proposed damage model is theoretically more reasonable and can accurately describe the seismic damage evolution of the SRHSC frame columns. The results also can be used as a new theoretic reference for the establishment of damage-based earthquake-resistant design method of SRHSC members.

Pseudo-dynamic test and numerical simulation of high-strength concrete frame structure reinforced with high-strength rebars

This paper describes an investigation of a high-strength concrete frame reinforced with high-strength rebars that was tested in the structure engineering laboratory at Shenyang Jianzhu University. The frame specimen was pseudodynamically loaded to indicate three earthquake ground motions of different hazard levels, after which the test specimen was subjected to a pseudo-static loading. This paper focuses on the design, construction and experiment of the test frame and validation of the simulation models. Research shows that a high-strength concrete frame reinforced with high-strength rebars is more efficient and economical than a traditional reinforced concrete frame structure. In addition to the economies achieved by effective use of materials, research shows that the frame can provide enough strength to exceed conventional reinforced concrete frames and provide acceptable ductility. The test study provides evidence to validate the performance of a high-strength concrete frame designed according to current seismic code provisions. Based on previous test research, a nonlinear FEM analysis is completed by using OpenSees software. The dynamic responses of the frame structure are numerically analyzed. The results of the numerical simulation show that the model can calculate the seismic responses of the frame by OpenSees. At the same time, the test provides additional opportunities to validate the performance of the simulation models.

Seismic Damage Law of Steel Reinforced High Strength and High Performance Concrete Frame Columns

In this paper, the damage performance of 13 SRHSHPC frame columns are tested and analyzed under low cycle loading. The effect of concrete strength, axial compression ratio and shear span ratio on the damage of SRHSHPC frame columns is discussed, and then the experimental result is quantified with damage index. Based on existing seismic damage models, a new seismic damage model is put forward for SRHSHPC frame columns by a nonlinear combination of deformation and accumulative dissipation.