Performance Of RC Frame Structures Research Articles

Seismic performance of RC frame structures with infill CLT shear walls

This paper focuses on the newly proposed RC-CLT hybrid wall systems used in residential buildings. Cyclic loading tests were conducted using 2-storey specimens, to confirm the seismic performance and behavior of the hybrid system and also to investigate the behavior of the RC beams in mid-level and the transmission of shear stress by the CLT wall from upper to lower level. The experimental results showed that CLT could potentially be more superior than RC wall infill in terms of ductility, due to CLT exhibiting higher inter-story drift during shear failure. Furthermore, this study proposes numerical models to simulate the experimental results of the hybrid systems. The RC structural members were modeled using linear elements with MS model inserted at the ends to consider for the N-M interactions. As for the CLT wall, it was modeled using several braced models. The numerical results generally show good agreements with the experimental results. As a result, the numerical model proposed in this study can contribute to better predict the structural behavior of CLT shear wall infilled RC frame with concealed steel plate and drift pin connections.

Seismic performance of RC frame structure across the earth fissure based on pushover analysis

This study aims to investigate the seismic performance and failure mechanism of reinforced concrete frame structures across the earth fissure. A five-story reinforced concrete frame structure across the earth fissure was tested by shaking table and the test equivalent finite element model was established by simulation software, the seismic performance of the reinforced concrete frame structure across the earth fissure was carried out and analyzed by these two methods. The results showed that the earth fissure has an amplification effect on the structure displacement response, the damage indexes and internal forces of the structure across the earth fissure were always larger than the structure on the ordinary site. The maximum damage index deviation increases from 6.1% to 11.4% under 0.2 g and 0.4 g seismic waves, and the maximum axial and shear forces deviation of column increases from 29% to 50% and 11.7% to 15.2% during 0.2 g to 0.6 g Cape Mendocino waves, respectively. With the increase of seismic intensity, the deviation of damage indexes and internal forces increased. The damage to the structure of the hanging wall were earlier and more seriously, and the first floor was the most vulnerable floor. The research in this paper has practical significance for seismic performance evaluation and provides reference for reinforced concrete frame structure across the earth fissure seismic design.

CLT壁をRC架構に内蔵する合成耐震壁の静的繰り返し載荷実験

In this study, static loading tests were performed to investigate the structural performance of RC frames with CLT walls. The experimental investigation revealed that the presence of CLT infill significantly increased the initial stiffness and strength of RC frame regardless the RC frame-CLT infill connections. The post-peak strength of the RC frame with CLT infill did not drop below 80% of the maximum strength even in a large drift of 10%. These results clarified that the presence of CLT infill within RC frame has a beneficial effect on the seismic performance of RC frame structure.

Shaking table test study on seismic performance of RC frame structure with NES

A new type of nonlinear vibration absorber NES (Nonlinear Energy Sink) studied in this paper belongs to the structural passive control technology, which consists of a horizontal track and an additional mass block. Acting as a damper absorb and dissipate energy, the NES completes the target energy transfer by generating a horizontal nonlinear restoring force and reduces the response of the main structure. In this paper theoretical analysis of the new NES was analyzed by the expression of the restoring force of the NES and the equation of motion of the additional NES system are deduced. Shaking table test was carried out on the 1:4 scale RC frame structure model installed with the new NES shock absorber, focusing on the research on the energy dissipation and shock absorption effect of the NES shock absorber, and whether it can improve the seismic performance of the RC frame structure damaged in the earthquake. The results show that the NES installed in the RC frame structure has sufficient nonlinear displacement and energy dissipation capacity under the moderate and strong earthquakes, showing a very good energy dissipation and shock absorption effect. The NES can reduce the top story displacement and acceleration response of the main structure under the action of earthquake; the top story displacement and absolute acceleration response are related to the natural frequency of the frame and the spectral characteristics of seismic waves, so that the vibration control effect is affected by the frequency spectrum of seismic waves. In the frequency domain analysis of the frame dynamic response, the nonlinear energy well exhibits the characteristics of broadband control. This type of NES significantly reduces the seismic response of damaged structures, improves the seismic performance of damaged structures under moderate to strong earthquakes, and decreases the risk of potential collapse and construction costs during earthquake aftershocks.

The Effects of Infilled Walls on Seismic Performance of RC Frame Structures with Eccentrically Placed Open Corridor

In this paper, an RC frame model with infilled walls was built and tested, including by a modal test, percussion test and shaking table test, the prototype of which was a collapsed teaching building with an eccentrically placed open corridor during the Wenchuan Earthquake in Xuankou Middle School. The natural frequency of the model was obtained by microseism testing, and the contribution of the infilled walls with different openings to the lateral stiffness of the model was discussed. In addition, the damping ratio, strain responses and internal force distribution of the columns were analysed by knocking the roof of the RC frame model, and then a shaking table test was conducted to study the seismic performance of the model. The results show that the value of longitudinal fundamental frequency increased from 1.88 Hz to 6.65 Hz, and the transverse one increased from 1.90 Hz to 13.40 Hz. The torsion frequency was increased by 6.65 times compared with that when the wall was not built. Furthermore, the damping ratio of the model was significantly increased after the infilled walls were built. When the floor moves longitudinally, the strain at the end of the columns restrained by semi-high continuous infilled walls is 2–4 times that in the unconstrained columns, and the shear force in the restrained columns is 4–8 times that in the unstrained columns. As a result, plastic hinges would form in the constrained columns; then, the columns would lose their vertical load capacity.

Assessment of seismic performance of RC frame structure with masonry infill panels partially uncoupled from the surrounding frame members

The present study numerically analyses the influence of physical and mechanical properties of the materials used for masonry infill panels upon the seismic response of low rise reinforced concrete frame structure. A four-storey residential building (benchmark), located in Timisoara, a moderate seismic area, has been designed according to the current Romanian design codes. Then, infill panels considered uncoupled from the frame members along their lateral and upper edges, have been added to the structure. Infill panels have been investigated in four variants, by using 2 types of masonry units (hollowed ceramic blocks and AAC), alternatively built with mortars specific for regular bed joints (G) and thin bed joints (T), for which a comparative modal response spectrum analysis has been carried out. The seismic behaviour of buildings in all these cases has been analysed in terms of peak inter-storey drifts under two limit states and of the out-of-plane strength of infill panels. The results show that the peak inter-storey drifts reductions compared to the benchmark structure are up to 59% at SLS, and 61% at ULS. Regarding the out-of-plane behaviour of the infill panels it was noted that safety verification is fulfilled only for one of the abovementioned cases. As a final remark, the results obtained in this study highlight the importance of physical and mechanical properties of the masonry infill panels in the assessments of seismic response of frame structure buildings.

Experimental and Numerical Assessment of Masonry Infill on Seismic Performance of RC Frame Structure

Experimental and Numerical Assessment of Masonry Infill on Seismic Performance of RC Frame Structure

Self-centering cable brace with friction devices for enhancing seismic performance of RC frame structures

A novel self-centering cable brace (SCCB) with friction devices is developed to improve the seismic performance of existing RC frame structures. This paper presents the structural configuration and the theoretical load-displacement relationship of the SCCB. Cyclic loading tests are conducted to show the effectiveness of the SCCB, and a numerical model is established and validated based on the test results. A parametric analysis is made to investigate the influence of tendon stiffness and friction on hysteretic performance of the SCCB. Nonlinear dynamic analyses are further carried out on a nine-story RC frame, which is seismically deficient and enhanced with buckling restrained braces (BRBs) and SCCBs respectively for comparison. Inter-story and residual inter-story drifts, base shear forces, load-axial elongation relationships and self-centering indexes of the bare and strengthened frames are obtained and compared. It is found that both the SCCBs and BRBs increase the seismic capacity, while the SCCBs can reduce the maximum story drifts more significantly and have much less residual story drifts than BRBs.

Effect of infill walls on cumulative plastic deformation energy of RC frame structures

PurposeA large number of earthquake damages showed that infill walls have obvious influence on the seismic damage performance of RC frame structures. The purpose of this paper is to study the effect of infill walls on the cumulative plastic deformation energy of RC frame structures, for which four RC frame structures are build and the time-history response analysis under unidirectional seismic action is presented.Design/methodology/approachThe time-history response analysis under unidirectional seismic action is presented. Then the effect of periodic reduction coefficient on the cumulative plastic deformation energy of the structures, the beams and the columns is investigated.FindingsFinally, the quantitative calculation formulas are provided. The results show that the periodic reduction coefficient has an obvious effect on the distribution of the accumulated plastic deformation energy, and the influence rules are presented here.Originality/valueThe effect of infill walls on the cumulative plastic deformation energy of RC frame structures is quantitatively analyzed here.

Seismic performance analysis of multi-story RC frames strengthened with RC infill wall

Seismic performance of RC frame structures was investigated by creating 3-D models of the frame with additional solid RC infill wall along the height of Honolulu Building prescribed in FEMA design examples. Layered-shell element (LSE) was used to model the infill wall and gap element was introduced at the interface between the wall and the bounding frames. The modelling technique was validated against test results reported in the literature prior to its application on the 12 story building. The push over curves of all models were compared to obtain the most efficient model that conform to the strength and stiffness requirement of the seismic codes of Indonesia. The results showed that the non-linear behaviour of RC frame with RC infill wall can be modelled accurately using LSE and gap element. The RC wall addition improved the strength, stiffness and performance of the frame significantly. The most efficient model was that with infill wall up to the first 4 story levels in which, the performance of the structure improved from collapse prevention to immediate occupancy.

Analysis of the Effect of Column-to-Beam Strength Ratio on Seismic Performance of RC Frame Structure

Strong column-weak beam is one of the important concepts in seismic design of RC frame structure. The experience of earthquake damage shows that the structure designed according to the existing codes cannot achieve the expected failure mode of strong column-weak beam due to the effects of factors such as axial compression ratio, slab and so on. In this paper, the RC frame structures are designed with column-to-beam strength ratio of 1.2, 1.4, 1.6, 1.8 and 2.0, and the structural responses are obtained using Push-over analysis. The effect of column-to-beam strength ratio on failure modes of RC frame structure is studied. The results show that the existence of slab affects the yield mechanism of steel bars in beams and columns, and further affects the possible failure modes of structures. In case of considering slab, increasing column-to-beam strength ratio can effectively enhance structural seismic capacity. The failure mode of strong column and weak beam can be achieved when the column-to-beam strength ratio is 1.8.

Seismic Damage and Collapse Assessment of Reinforced Concrete Frame Structures Using a Component‐Classification Weighted Algorithm

The seismic performance of reinforced concrete members under earthquake excitation is different from that of whole structures; collapse mechanism may occur because of severe damage to individual members, even if the structural damage is not significant. Therefore, the potential seismic damage of each member should be investigated specifically apart from that of overall structure. In this study, a global damage model based on component classification is proposed to analyze the structural damage evolution rule and failure mechanism; then, the computed damage is compared with the experimental phenomena of three 1/3‐scale models of three‐storey, three‐bay reinforced concrete frame structures under low‐reversed cyclic loading. In addition, a probabilistic approach is finally adopted to quantify the seismic performance of RC frame structures based on the proposed global damage model. Results indicate that the structures with lower vertical axial force and beam‐to‐column linear stiffness ratio still maintain a certain load‐bearing capacity even when the interstorey drift angle exceeds the elastoplastic limit value and the cumulative damage of structures is mainly concentrated on the beam ends and column bottoms of the first floor at final collapse. Moreover, the structural failure probability at different performance levels would increase significantly if reinforced concrete frame structures suffer ground motions higher than the design fortification intensity, even up to eight times.

Multifactor Influence Analysis of Seismic Performance of RC Frame Structure with Cast-in-site Slabs

Abstract Pushover and nonlinear dynamic analysis method are applied to analyze the seismic performance of RC frame structure with or without slabs under the action of multiple factors in this thesis. Meanwhile, the structural response exerted by oblique seismic action is summarized from the theoretical formula derivation. By analyzing and comparing two kinds of established models, the results demonstrate that with various axial compression ratio and moment magnifying factors of columns, the seismic performance of the structure will be degraded when the influence of the floor is taken into account. And the increment of the values of axial compression ratio μ and moment magnifying factor of column η c with the floor exceeds that without the floor. Moreover, Earthquakes input along the principal axis can realize the “strong column weak beam” of the structure. Considering the influence of floor, when the value of axial compression ratio is higher than 0.56 or moment magnifying factors with the floor increases above 2.0, frame structure under oblique seismic action can form “strong column weak beam” yield mechanism.

Uncertainty and Sensitivity Analysis of Reinforced Concrete Frame Structures Subjected to Column Loss

AbstractIn this study, the variability inherent in the performance of RC frame structures to bridge over a column loss was investigated, considering the uncertainties existing in gravity loads, material properties, and construction geometries. Uncertainty and sensitivity analysis were conducted in tandem to provide the influence and significance of the uncertain parameters on RC frames to resist progressive collapse. Quasi-static pushdown analysis was used to assess the residual load-resisting capacity of structures with an initialized damage. A set of structural models were generated for uncertainty analysis by using the correlation-reduced Latin hypercube sampling method. Sensitivity analysis was performed by independently varying parameters with one standard deviation away from their means. Two typical RC frame structures with different span aspect ratios were taken as the study cases. The macromodeling technique, which was validated by the test results, was used for analysis. The study results indicat...

Seismic behavior of SMA–FRP reinforced concrete frames under sequential seismic hazard

Accumulation of plastic deformation under excessive loads, is one of the most critical drawbacks in steel reinforced concrete structures. Permanent plastic deformation of steel rebars is among the main reasons for the disruption of the functionality of RC structures after major seismic events. It can also pose life threatening risks in case of strong aftershock occurrence. In an attempt to address the problem of excessive permanent deformations and their impact on the post-earthquake functionality of concrete moment resisting frame (MRF) structures, this paper studies analytically a new type of reinforcing bars made of fiber reinforced polymer (FRP) with embedded superelastic shape memory alloy (SMA) fibers. SMA–FRP reinforcement is characterized with both ductility and pseudo-elasticity which are two important characteristics that are sough in this study to enhance the ability of RC moment frames to withstand strong sequential ground motions (i.e. main shock followed by one or more aftershocks). In this study, experimentally validated SMA–FRP material models are used in structural level models to assess the performance of RC frame structures under seismic loading. Three-story, one-bay prototype RC MRFs, reinforced with steel and SMA–FRP composite reinforcements are first designed using performance based criteria and then subjected to incremental dynamic analysis under sequential ground motions. Comparison is drawn between steel and SMA–FRP reinforced frames based on accumulation of damage and residual drifts. Numerical results show superior performance of SMA–FRP composite reinforced MRF in terms of dissipation of energy and accumulation of lower residual drifts. Increased demands from the effects of aftershock causes accumulation of residual drifts in steel reinforced frames which is mitigated in SMA–FRP reinforced frame through re-centering capability.

SEISMIC EVALUATION OF RC SPACE FRAME WITH RECTANGULAR AND EQUIVALENT SQUARE COLUMN BY PUSHOVER ANALYSIS

The present study is carried out to compare the seismic performance of RC frame structures of G+15 storey which consisting of rectangular shaped column as against equivalent square shaped column. The building is having 4.5m x 4.5m panels in both directions forming an overall plan dimension of 31.5m x 13.5m. All the beams are considered as 300 mm x 600 mm in size and columns with of 3 m height in each floor. In the above model all the rectangular shaped columns are oriented with longer side in global Y direction and shorter side parallel to global X direction. The M25 grade of concrete and Fe 415 grade of steel is considered for design. Pushover analysis is carried out, using commercially available software ETABS and behavior of RC frames is studied. One more factor which is studied in the current models is the material consumption variation for keeping the building in Immediate Occupancy stage. Also the comparison of normal RC frame and immediate occupancy level RC frame for both shaped columns is carried out. Quantity of concrete and quantity of steel is calculated for all the models and the overall structural cost is evaluated. Comparison for all the models in terms of quantity of materials and structural cost is also reported. It is concluded that the square cross section of columns perform better as compared to rectangular cross section of columns.

Analysis of the Seismic Performance of RC Frame Structures with Different Types of Bracings

Finite element models of frames with steel-bracings and with concrete filled steel tube struts are built in ETABS. Seismic performance of these models is analyzed with base-shear method, superposition of modal responses method and time history method respectively. The results show that the steel-bracings or concrete filled steel tube struts are efficient to increase the story-stiffness, and the top displacement of the frame structure decreases significantly.

Nonlinear Analysis of a RC Frame Structure with Semi-Interlayers Damaged during Wenchuan Earthquake

Under the excitation of large earthquake, structures enter into high nonlinear stage. Currently, Opensees, Perform-3d and Canny are used as the most popular nonlinear analysis procedures. The fiber model will be introduced firstly and the nonlinear analysis models in Canny are explained in detail. Then Canny2007 is used to conduct nonlinear time history analysis on a heavily damaged frame structure with interlayer in Dujiangyan during Wenchuan Earthquake. Analysis shows that the maximum inter-story drift appears between the interlayer and its upper layer, and the heavy damage agrees well with the results of damage investigation. By comparing the damage extent of frame structures with or without interlayer, it reveals that the seismic performance of RC frame structures without interlayer is obviously better than that of ones with interlayer.