Shear Resistant Behavior of RC Columns Subjected to Axial Pulse-Like Ground Motions

2013 ◽  
Vol 639-640 ◽  
pp. 832-835
Author(s):  
Wei Feng Zhao ◽  
Xiao Quan Hu ◽  
Qin Chen
Keyword(s):  
Axial Velocity ◽  
Ground Motions ◽  
Time History ◽  
Load Ratio ◽  
Spectral Ratio ◽  
Shear Capacity ◽  
Velocity Pulse ◽  
Rc Columns ◽  
Shear Span ◽  
Earthquake Records

The shear-resistant behavior of reinforced concrete (RC) columns subjected to axial velocity pulse-like ground motions was studied. Single RC columns with the constant vertical and horizontal fundamental period were used to investigate the influences of fault-distance of earthquake records, vertical to horizontal acceleration spectral ratio of earthquake records, initial axial load ratio and shear span ratio of RC column, on the shear-resistant behavior of RC columns. a suite of 18 strong ground motion records from Chi-chi earthquake divided into three fault-distance groups were taken as excitations to execute nonlinear dynamic time history analysis. The results demonstrated that axial velocity pulse-like earthquake action (fault-distance) had significant influences on the shear resistant-resistant of RC columns. Shear-resistant behavior (shear capacity/shear demand) increases with the increasing of fault-distance. Fault-distance and shear span ratio had a certain coupling influences on the shear-resistant behavior of RC columns.

scholarly journals Experimental Inspection on Shear Capacity in RCC Beams with Partial Replacement of Recycled Coarse Aggregates

2020 ◽  
Vol 9 (2) ◽  
pp. 321-326
Keyword(s):  
Compressive Strength ◽  
Load Ratio ◽  
Shear Capacity ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Age Group ◽  
Shear Span ◽  
Coarse Aggregates ◽  
The Relationship

Demolition waste increasing day by day. The old damaged building materials can be used in present buildings or other construction works. Especially the recycled aggregates are useful to the concrete structures. The experimental studies on the use of recycled coarse aggregate has been going on for many countries. This publication focuses on the relationship between the shear capacity and the flexural cracking load of reinforced recycled concrete beams with stirrups, this experimental Inspection with partial replacement of natural coarse aggregates (NAC) with recycled coarse aggregates (RAC) at different ages as 10, 20 and 30 years in various proportions as 20 per cent, 30 per cent, 40 per cent. For this, M30 grade of concrete is consider. Curing of specimens were done for 7 day and 28 days to conclude the maximum strengths. The obtained results of concrete with partial replacement of recycled aggregates of 10,20and 30 years age group conclude maximum compressive strength of 35.84 N/mm2 at 40% replacement of NCA with RCA of age group (10 years) and 34.12 N/mm2 at 30% replacement of NCA whit RCA of (20 years) age group and 36.14 N/mm2 20% replacement of NCA with RCA of age group (30 years). After the compressive strength, beam specimens were casted for 7day and 28 days. Based on test results of 8 beams, the relationship between the cracking load that causes a beam to crack in the middle of the shear span and the beam's shear capacity is confident. All beams are reinforced in the longitudinal direction only and only tested under two-point loading conditions. The average analytical cracking load ratio is 0.60.the mid-shear span at cracking load (Vcr-a/2) in comparison with the observed shear capacity (Vexp). The analytical cracking load ratio. The analytical cracking’s load was used in this exploration as it is more reliable than the observed cracking load. At mid-span, the shear capacity of most of the beams was shown to be 50%. The average shear capacity ratio to the related test crack load in the center of the shear span 0.43. The analysis showed that cracking loads are strongly related to the shear capacity of the members. This relationship can be used to develop recycled reinforced beam members ' shear design process.

Seismic Performance of Base-Isolation Building Subjected to Near-Fault Ground Motion with Velocity Pulse

2014 ◽  
Vol 580-583 ◽  
pp. 1700-1703
Author(s):  
Qiu Mei He ◽  
Ya Qi Li ◽  
Ya Min Zhao ◽  
Yu Yang
Keyword(s):  
Seismic Response ◽  
Seismic Performance ◽  
Base Isolation ◽  
Ground Motions ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Seismic Structure ◽  
Velocity Pulse ◽  
Near Fault ◽  
Rubber Bearings

The seismic response of the base-isolated structure can be reduced significantly in the far-field region compared to the conventional seismic structure. However, near-fault ground motions with velocity pulse may cause the adverse influence on the seismic performance of the base-isolation building, which needs to be investigated deeply. In this paper 6 ground motions with velocity pulse are selected as the input, and the seismic response of a 9 layers conventional seismic RC frame building and comparative base-isolation building with lead-core rubber bearings are obtained by nonlinear time history analysis. The result indicates that base-isolation building with lead-core rubber bearings are of good aseismic performance under the near-fault ground motions with velocity pulse.

Review on Seismic Behavior of RC Columns

2013 ◽  
Vol 353-356 ◽  
pp. 2092-2096
Author(s):  
Yong Ping Xie ◽  
Lei Jia ◽  
Gang Sun
Keyword(s):  
Axial Load ◽  
Seismic Behavior ◽  
Large Scale ◽  
Load Ratio ◽  
Concrete Columns ◽  
Shear Capacity ◽  
Economic Damage ◽  
Rc Columns ◽  
Axial Load Ratio ◽  
Mode Of Failure

Column is the key member of the seismic structures, after the earthquake destroyed, not only cause column serious economic damage, and will cause a large number of casualties. For studying the seismic behavior and size effect of full-scale reinforced concrete columns. A comprehensive summary of the experimental results is undertaken to evaluate the seismic behavior of RC concrete columns, including test equipment and load method and mode of failure and Seismic behavior. It is concluded that the ductility and shear capacity of RC mainly depends on shear span ratio, axial load ratio and stirrup ratio. But the seismic behavior of large scale RC columns has no systematic studied.

Shear response of steel fiber reinforced recycled concrete-filled steel tube columns

2021 ◽  
pp. 136943322110093
Author(s):  
Zhenzhen Liu ◽  
Yiyan Lu ◽  
Shan Li ◽  
Jiancong Liao
Keyword(s):  
Axial Compression ◽  
Steel Fiber ◽  
Steel Tube ◽  
Shear Capacity ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Superposition Method ◽  
Fiber Reinforced ◽  
Concrete Filled Steel Tube ◽  
Shear Span

A comprehensive study of the shear characteristics of steel fiber reinforced recycled concrete-filled steel tube (SRCFST) columns is conducted. 50 CFST stub columns are tested with the variables of steel tube diameter-thickness ratio ( D/t), shear span-to-depth ratio (λ), axial compression ratio ( n), and concrete mix. Two types of cements, three recycled aggregate percentages, three water-cement ratios, and three steel fiber contents are considered in design of concrete mixes. The experimental results show that SRCFST columns present the coincident shear behavior of the ordinary CFST columns. As λ is increased, shear resistance shows a downtrend, while the flexural strength presents an increasing trend. Imposing axial compression or thickening steel tube contributes to an adequate safety margin in plastic period. Based on the contributions superposition method, a predicted model of the shear capacity of SRCFST columns is proposed in consideration of shear-span ratio, axial compression, and self-stress.

Seismic response analysis of steel–concrete hybrid wind turbine tower

2021 ◽  
pp. 107754632110075
Author(s):  
Junling Chen ◽  
Jinwei Li ◽  
Dawei Wang ◽  
Youquan Feng
Keyword(s):  
Wind Turbine ◽  
Response Spectrum ◽  
Ground Motions ◽  
Time History ◽  
Seismic Action ◽  
Response Spectrum Method ◽  
Spectrum Method ◽  
Wind Turbine Tower ◽  
Ground Types ◽  
Nonlinear Time History

The steel–concrete hybrid wind turbine tower is characterized by the concrete tubular segment at the lower part and the traditional steel tubular segment at the upper part. Because of the great change of mass and stiffness along the height of the tower at the connection of steel segment and concrete segment, its dynamic responses under seismic ground motions are significantly different from those of the traditional steel tubular wind turbine tower. Two detailed finite element models of a full steel tubular tower and a steel–concrete hybrid tower for 2.0 MW wind turbine built in the same wind farm are, respectively, developed by using the finite element software ABAQUS. The response spectrum method is applied to analyze the seismic action effects of these two towers under three different ground types. Three groups of ground motions corresponding to three ground types are used to analyze the dynamic response of the steel–concrete hybrid tower by the nonlinear time history method. The numerical results show that the seismic action effect by the response spectrum method is lower than those by the nonlinear time history method. And then it can be concluded that the response spectrum method is not suitable for calculating the seismic action effects of the steel–concrete hybrid tower directly and the time history analyses should be a necessary supplement for its seismic design. The first three modes have obvious contributions on the dynamic response of the steel–concrete hybrid tower.

scholarly journals Influence of Patching on the Shear Failure of Reinforced Concrete Beam without Stirrup

2021 ◽  
Vol 6 (7) ◽  
pp. 97
Author(s):  
Stefanus Adi Kristiawan ◽  
Halwan Alfisa Saifullah ◽  
Agus Supriyadi
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Numerical Study ◽  
Unsaturated Polyester ◽  
Reinforced Concrete Beam ◽  
Concrete Cover ◽  
Shear Capacity ◽  
Rc Beam ◽  
Shear Span ◽  
Shear Cracking

Deteriorated concrete cover, e.g., spalling or delamination, especially when it occurs at the web of a reinforced concrete (RC) beam within the shear span, can reduce the shear capacity of the beam. Patching of this deteriorated area may be the best option to recover the shear capacity of the beam affected. For this purpose, unsaturated polyester resin mortar (UPR mortar) has been formulated. This research aims to investigate the efficacy of UPR mortar in limiting the shear cracking and so restoring the shear capacity of the deteriorated RC beam. The investigation is carried out by an experimental and numerical study. Two types of beams with a size of 150 × 250 × 1000 mm were prepared. The first type of beams was assigned as a normal beam. The other was a beam with a cut off in the non-stirrup shear span, which was eventually patched with UPR mortar. Two reinforcement ratios were assigned for each type of beams. The results show that UPR mortar is effective to hamper the propagation of diagonal cracks leading to increase the shear failure load by 15–20% compared to the reference (normal) beam. The increase of shear strength with the use of UPR mortar is consistently confirmed at various reinforcement ratios.

Characteristics of long-period microtremors and their applicability in exploration of deep sedimentary layers

1994 ◽  
Vol 84 (6) ◽  
pp. 1831-1841 ◽  
Author(s):  
Hiroaki Yamanaka ◽  
Masayuki Takemura ◽  
Hiroshi Ishida ◽  
Masanori Niwa
Keyword(s):  
Rayleigh Waves ◽  
Ground Motions ◽  
Spectral Ratio ◽  
Northwestern Part ◽  
Trial And Error ◽  
Sediment Thickness ◽  
Short Term ◽  
Subsurface Structures ◽  
Long Period ◽  
Good Agreement

Abstract Applicability of long-period microtremors in inferring subsurface structure is examined using measurements of microtremors in the northwestern part of the Kanto Plain in Japan. Short-term continuous measurements of long-period microtremors at both sediment and basement sites were taken. A spectral peak at a period of 4 to 5 sec is stable with time, while peaks at periods less than 2 sec are time variant, suggesting a variation of microtremor sources. However, it was found that the spectral ratio between vertical and horizontal microtremors (ellipticity) at each site is stable with time. Good agreement was found between ellipticities of microtremors at the sediment site and those computed for Rayleigh waves in which the structure of the sediments beneath the site was taken into account. We also found that the ellipticities of Rayleigh waves in earthquake ground motions were consistent with those of the microtremors. These comparisons provide strong evidence that long-period microtremors in the area studied consist mainly of Rayleigh waves. The ellipticity of microtremors was investigated by observing microtremors at temporary observation sites in the Kanto Plain where the sediment thickness varied from 0 to 1 km. The subsurface structures were deduced by trial-and-error fitting of observed ellipticities with theoretical ellipticities that were calculated assuming Rayleigh waves. These results show that ellipticity of long-period microtremors is effective for deducing structure from microtremor data at a single site.

A statistical study on artificially generated earthquake records

1976 ◽  
Vol 3 (1) ◽  
pp. 11-19
Author(s):  
W. K. Tso ◽  
B. P. Guru
Keyword(s):  
Statistical Study ◽  
Spectral Response ◽  
Flexible Structures ◽  
Time History ◽  
Maximum Response ◽  
Response Analysis ◽  
Seismic Region ◽  
Natural Period ◽  
Earthquake Records ◽  
Time History Response

A statistical study has been done to investigate (i) the variation of spectral responses of structures due to artificially generated earthquake records with identical statistical properties, (ii) the effect of duration of strong shaking phase of artificial earthquakes on the response of structures, and (iii) the number of earthquake records needed for time-history response analysis of a structure in a seismic region. The results indicate that the flexible structures are more sensitive to the inherent statistical variations among statistically identical earthquake records. Consequently several records must be used for time-history response analysis. A sample of eight or more records appear to provide a good estimate of mean maximum response. The duration of strong shaking can significantly affect the maximum response. Based on the results, it is suggested that for the purpose of estimating peak response, the strong shaking duration of the input earthquake motion should be at least four times the natural period of the structure. The maximum responses due to statistically identical ground motion records are observed to fit approximately the type 1 extreme value distribution. Thus, it is rationally possible to choose a design value based on the mean, standard deviation of the spectral response values and tolerable probability of exceedance.

scholarly journals Evaluation of Modified Fish-Bone Model for Estimating Seismic Demands of Irregular MRF Structures

2018 ◽  
Author(s):  
Amin Haghighat ◽  
Ashkan Sharifi
Keyword(s):  
Ground Motions ◽  
Fish Bone ◽  
Seismic Demands ◽  
Error Measure ◽  
Ductility Demand ◽  
Earthquake Records ◽  
Moment Resisting Frame ◽  
Different Types ◽  
Story Drift ◽  
Moment Resisting

This paper evaluates the accuracy of the Modified Fish-Bone (MFB) model for estimating the maximum inter-story drift ratio of irregular moment resisting frame (MRF) structures. To make this model applicable to irregular MRF structures, some modifications are made to the MFB formula. In order to evaluate the accuracy of the MFB model, several irregular frames with different types of irregularities are considered when subjected to different ground motions with different intensities. A local and a global error measure are defined and they are calculated for different frame models subjected to different earthquake records. The effects of different irregularities, ductility demand and frame height on the accuracy of the MFB model are investigated. Based on the results obtained from this evaluation, two simple and effective approaches are suggested to improve the MFB models.

A Seismic Effective Method for Double-Layer Reticulated Shell Using Buckling-Restrained Braces

2010 ◽  
Vol 163-167 ◽  
pp. 2852-2856
Author(s):  
Chang Wu ◽  
Xiu Li Wang
Keyword(s):  
Double Layer ◽  
Seismic Performance ◽  
Linear Time ◽  
Ground Motions ◽  
Equations Of Motion ◽  
Time History ◽  
Original Structure ◽  
Loading Test ◽  
Strong Earthquakes ◽  
Buckling Restrained Braces

In this study a kind of buckling-restrained braces (BRBs) as energy dissipation dampers is attempted for seismic performance of large span double-layer reticulated shell and the effectiveness of BRBs to protect structures against strong earthquakes is numerically studied. The hysteretic curve of such members is obtained through the simulation of the cyclic-loading test, and the equations of motion of the system under earthquake excitations are established. BRBs are then placed at certain locations on the example reticulated shell to replace some normal members, and the damping effect of the two installation schemes of BRBs is investigated by non-linear time-history analyses under various ground motions representing major earthquake events. Compared with the seismic behavior of the original structure without BRBs, satisfactory seismic performance is seen in the upgraded models, which clarifies the BRBs can reduce the vibration response of spatial reticulated structure effectively and the new system has wide space to develop double layer reticulated shell.

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