Pub Date : 2017-12-31DOI: 10.5459/BNZSEE.50.4.517-526
T. Kabeyasawa, Toshikazu Kabeyasawa, H. Fukuyama
The effects of floor slabs on the flexural strength of beams in reinforced concrete buildings under seismic action were verified through tests of frame assembly specimens. A series of experimental and analytical investigations were conducted from 2010 to 2014 in order to further validate the current design practices in Japan. Loading methods in the past beam component tests were reviewed with probable effects of floor slabs. A special loading set-up was used for the frame assembly specimens consisting of four columns and four beams with lengths of one span and two half spans in two directions. The four columns were loaded laterally and independently at mid-height of the upper storey and supported at mid-height of the lower storey with pinfixed and pin-roller so that axial elongation of the beams and slab would not be constrained by the lateral forces. It has been found from these new loading tests that the tensile stresses in the floor slab reinforcing bars are generally uniform at the beam critical sections and up to the full slab width for the flexural strength when the slab is subjected to tension bending around one percent storey drift, which is much wider than assumed in the current design evaluation.
{"title":"Effects of floor slabs on the flexural strength of beams in reinforced concrete buildings","authors":"T. Kabeyasawa, Toshikazu Kabeyasawa, H. Fukuyama","doi":"10.5459/BNZSEE.50.4.517-526","DOIUrl":"https://doi.org/10.5459/BNZSEE.50.4.517-526","url":null,"abstract":"The effects of floor slabs on the flexural strength of beams in reinforced concrete buildings under seismic action were verified through tests of frame assembly specimens. A series of experimental and analytical investigations were conducted from 2010 to 2014 in order to further validate the current design practices in Japan. Loading methods in the past beam component tests were reviewed with probable effects of floor slabs. A special loading set-up was used for the frame assembly specimens consisting of four columns and four beams with lengths of one span and two half spans in two directions. The four columns were loaded laterally and independently at mid-height of the upper storey and supported at mid-height of the lower storey with pinfixed and pin-roller so that axial elongation of the beams and slab would not be constrained by the lateral forces. It has been found from these new loading tests that the tensile stresses in the floor slab reinforcing bars are generally uniform at the beam critical sections and up to the full slab width for the flexural strength when the slab is subjected to tension bending around one percent storey drift, which is much wider than assumed in the current design evaluation.","PeriodicalId":343472,"journal":{"name":"Bulletin of the New Zealand National Society for Earthquake Engineering","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127733970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-31DOI: 10.5459/BNZSEE.50.4.537-546
K. Kusunoki, Chikashi Nishikura, A. Tasai
Recently, earthquake damage to non-structural walls has become one of the important issues in Japan. Some buildings were demolished after the 2011 Tohoku Earthquake due to damage of non-structural walls without any significant damage in structural members. After that, several projects were launched to develop a new method to take into account the effect of non-structural walls (hanging, standing, and wing walls). In this paper, experimental test results for beam-column joints with non-structural walls are presented. The objectives of the tests were to investigate the equivalent length and hinge location of beams with hanging and standing walls. The results showed that the yield hinge located at the surface of the wing walls and beam-column joint should be modelled as rigid to estimate the deformation of the beams, regardless of the thickness and height of the wall. A tri-linear modelling method for beams with hanging and standing walls was also proposed, and its applicability was confirmed with the test results.
{"title":"Experimental study on the seismic behaviour of RC beams with standing and hanging walls","authors":"K. Kusunoki, Chikashi Nishikura, A. Tasai","doi":"10.5459/BNZSEE.50.4.537-546","DOIUrl":"https://doi.org/10.5459/BNZSEE.50.4.537-546","url":null,"abstract":"Recently, earthquake damage to non-structural walls has become one of the important issues in Japan. Some buildings were demolished after the 2011 Tohoku Earthquake due to damage of non-structural walls without any significant damage in structural members. After that, several projects were launched to develop a new method to take into account the effect of non-structural walls (hanging, standing, and wing walls). In this paper, experimental test results for beam-column joints with non-structural walls are presented. The objectives of the tests were to investigate the equivalent length and hinge location of beams with hanging and standing walls. The results showed that the yield hinge located at the surface of the wing walls and beam-column joint should be modelled as rigid to estimate the deformation of the beams, regardless of the thickness and height of the wall. A tri-linear modelling method for beams with hanging and standing walls was also proposed, and its applicability was confirmed with the test results.","PeriodicalId":343472,"journal":{"name":"Bulletin of the New Zealand National Society for Earthquake Engineering","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122053212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-31DOI: 10.5459/BNZSEE.50.4.595-607
J. Watkins, S. Sritharan, T. Nagae, R. Henry
Prior research into low-damage wall systems has predominately focused on the walls behaviour in isolation from other building components. Although the response of these isolated walls has been shown to perform well when subjected to both cyclic and dynamic loading, uncertainty exists when considering the effect of interactions between walls and other structural and non-structural components on the seismic response and performance of entire buildings. To help address this uncertainty a computational model was developed to simulate the response of a full-scale four-storey building with post-tensioned precast concrete walls that was subjected to tri-axial earthquake demands on the E-Defence shake table. The model accurately captured the buildings measured response by incorporating the in-plane and out-of-plane non-linear behaviour of both the wall and floor elements. The model was able to simulate the deformation demands imposed on the floor due to compatibility with the post-tensioned walls, closely matching the behaviour and damage observed during the test. Dynamic loading and wall-to-floor interaction were shown to significantly increase the over-strength actions that developed when compared to the wall system considered in isolation.
{"title":"Computational Modelling of a Four Storey Post-Tensioned Concrete Building Subjected to Shake Table Testing","authors":"J. Watkins, S. Sritharan, T. Nagae, R. Henry","doi":"10.5459/BNZSEE.50.4.595-607","DOIUrl":"https://doi.org/10.5459/BNZSEE.50.4.595-607","url":null,"abstract":"Prior research into low-damage wall systems has predominately focused on the walls behaviour in isolation from other building components. Although the response of these isolated walls has been shown to perform well when subjected to both cyclic and dynamic loading, uncertainty exists when considering the effect of interactions between walls and other structural and non-structural components on the seismic response and performance of entire buildings. To help address this uncertainty a computational model was developed to simulate the response of a full-scale four-storey building with post-tensioned precast concrete walls that was subjected to tri-axial earthquake demands on the E-Defence shake table. The model accurately captured the buildings measured response by incorporating the in-plane and out-of-plane non-linear behaviour of both the wall and floor elements. The model was able to simulate the deformation demands imposed on the floor due to compatibility with the post-tensioned walls, closely matching the behaviour and damage observed during the test. Dynamic loading and wall-to-floor interaction were shown to significantly increase the over-strength actions that developed when compared to the wall system considered in isolation.","PeriodicalId":343472,"journal":{"name":"Bulletin of the New Zealand National Society for Earthquake Engineering","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126533109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-31DOI: 10.5459/BNZSEE.50.4.565-573
T. Mukai, Toshikazu Kabeyasawa, M. Tani, H. Suwada, H. Fukuyama
In order to use a damaged building continuously after earthquake, owners and/or stakeholders need to understand residual seismic capacity of the building. In Japan, a method to evaluate residual seismic capacity for damaged buildings had been developed. In order to evaluate residual seismic capacity of damaged building, the damage level of structural elements should be evaluated properly. This paper presents the results of damage analysis based on experimental data obtained from a full-scale static loading test [1] on a five-story reinforced concrete building tested at Building Research Institute. The damage rating for the specimens evaluated by the residual seismic capacity concept [3] was ”Moderate” or ”Heavy” at 0.5% and 1% building drift angle despite the structure maintaining horizontal load carrying capacity. This implies that the applied method gives a conservative result for ductile buildings, such as relatively new moment resisting frames designed after 1981. In order to apply the method used in this paper to new buildings, the damage evaluation method for structural elements should be advanced more in the future. INTRODUCTION When severe earthquake occurs, some buildings have several damages and the original seismic performance deteriorates. After earthquake, owners and/or users need to understand damage level of their damaged buildings to determine whether they can continuously use the building. In Japan, an existing standard describes a method to evaluate damage level of RC buildings using residual seismic capacity ratio which is defined as the ratio of the seismic capacity of the damaged building under earthquake to the original seismic capacity [1]. The evaluation method was developed based on the residual seismic capacity obtained from the damage data of actual damaged buildings due to past severe earthquake. However, investigations on residual seismic capacity of full-scale ductile RC frame specimens have never been carried out. This paper shows the results from damage rating of an entire building structure evaluated by the residual seismic capacity concept based on the standard in Japan and the validity of the method is discussed. LOADING TEST A static loading test on a full-scale reinforced concrete building was carried out as described in the past paper [2]. The specimen is a full-scale five story reinforced concrete building with 2 bays in the loading direction and one bay in the transverse direction, and was constructed in a laboratory of Building Research Institute at Tsukuba. The elevation of the specimen is shown in Fig.1. The story height is 3.5 m and the total height of the specimen is 17.5 m (Fig.1). The span length is 6.0 m in both directions. There are two types of openings (2.0m×1.8m and 1.0m×1.8m) symmetrically positioned on the walls along the loading direction. There are structural gaps provided at the end of the openings as shown in Fig.2 (a). The vertical walls between openings are completely separated from the
{"title":"Residual seismic capacity of ductile RC frame with wing walls based on full-scale loading test","authors":"T. Mukai, Toshikazu Kabeyasawa, M. Tani, H. Suwada, H. Fukuyama","doi":"10.5459/BNZSEE.50.4.565-573","DOIUrl":"https://doi.org/10.5459/BNZSEE.50.4.565-573","url":null,"abstract":"In order to use a damaged building continuously after earthquake, owners and/or stakeholders need to understand residual seismic capacity of the building. In Japan, a method to evaluate residual seismic capacity for damaged buildings had been developed. In order to evaluate residual seismic capacity of damaged building, the damage level of structural elements should be evaluated properly. This paper presents the results of damage analysis based on experimental data obtained from a full-scale static loading test [1] on a five-story reinforced concrete building tested at Building Research Institute. The damage rating for the specimens evaluated by the residual seismic capacity concept [3] was ”Moderate” or ”Heavy” at 0.5% and 1% building drift angle despite the structure maintaining horizontal load carrying capacity. This implies that the applied method gives a conservative result for ductile buildings, such as relatively new moment resisting frames designed after 1981. In order to apply the method used in this paper to new buildings, the damage evaluation method for structural elements should be advanced more in the future. INTRODUCTION When severe earthquake occurs, some buildings have several damages and the original seismic performance deteriorates. After earthquake, owners and/or users need to understand damage level of their damaged buildings to determine whether they can continuously use the building. In Japan, an existing standard describes a method to evaluate damage level of RC buildings using residual seismic capacity ratio which is defined as the ratio of the seismic capacity of the damaged building under earthquake to the original seismic capacity [1]. The evaluation method was developed based on the residual seismic capacity obtained from the damage data of actual damaged buildings due to past severe earthquake. However, investigations on residual seismic capacity of full-scale ductile RC frame specimens have never been carried out. This paper shows the results from damage rating of an entire building structure evaluated by the residual seismic capacity concept based on the standard in Japan and the validity of the method is discussed. LOADING TEST A static loading test on a full-scale reinforced concrete building was carried out as described in the past paper [2]. The specimen is a full-scale five story reinforced concrete building with 2 bays in the loading direction and one bay in the transverse direction, and was constructed in a laboratory of Building Research Institute at Tsukuba. The elevation of the specimen is shown in Fig.1. The story height is 3.5 m and the total height of the specimen is 17.5 m (Fig.1). The span length is 6.0 m in both directions. There are two types of openings (2.0m×1.8m and 1.0m×1.8m) symmetrically positioned on the walls along the loading direction. There are structural gaps provided at the end of the openings as shown in Fig.2 (a). The vertical walls between openings are completely separated from the ","PeriodicalId":343472,"journal":{"name":"Bulletin of the New Zealand National Society for Earthquake Engineering","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114432058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-31DOI: 10.5459/BNZSEE.50.4.504-516
F. Dashti, R. Dhakal, S. Pampanin
This paper presents an experimental study conducted to investigate the seismic performance and out-of-plane response of three rectangular doubly reinforced ductile wall specimens subjected to an in-plane cyclic quasi-static loading. The specimens were half-scale, representing the first story of four story prototype walls designed according to NZS3101:2006. The experimental program including details of the specimens, material properties, test setup, loading protocol and instrumentation is described. Also, the test observations, with focus on the significant stages of wall response as well as the failure patterns of the specimens, are reported considering the correlation between seismic damage and lateral drift. Two of the specimens failed at 2% drift, and their failure modes comprised of bar fracture, bar buckling, concrete crushing and out-of-plane instability. The failure pattern of the third specimen was pure out-of-plane instability which proved to have the potential to cause sudden collapse of slender ductile walls that are designed to resist other failure modes. In light of the test results, the efficacy of wall design provisions in the New Zealand concrete design standard (NZS3101) associated with the observed failure modes is scrutinised.
{"title":"Tests on slender ductile structural walls designed according to New Zealand Standard","authors":"F. Dashti, R. Dhakal, S. Pampanin","doi":"10.5459/BNZSEE.50.4.504-516","DOIUrl":"https://doi.org/10.5459/BNZSEE.50.4.504-516","url":null,"abstract":"This paper presents an experimental study conducted to investigate the seismic performance and out-of-plane response of three rectangular doubly reinforced ductile wall specimens subjected to an in-plane cyclic quasi-static loading. The specimens were half-scale, representing the first story of four story prototype walls designed according to NZS3101:2006. The experimental program including details of the specimens, material properties, test setup, loading protocol and instrumentation is described. Also, the test observations, with focus on the significant stages of wall response as well as the failure patterns of the specimens, are reported considering the correlation between seismic damage and lateral drift. Two of the specimens failed at 2% drift, and their failure modes comprised of bar fracture, bar buckling, concrete crushing and out-of-plane instability. The failure pattern of the third specimen was pure out-of-plane instability which proved to have the potential to cause sudden collapse of slender ductile walls that are designed to resist other failure modes. In light of the test results, the efficacy of wall design provisions in the New Zealand concrete design standard (NZS3101) associated with the observed failure modes is scrutinised.","PeriodicalId":343472,"journal":{"name":"Bulletin of the New Zealand National Society for Earthquake Engineering","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116032479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-31DOI: 10.5459/BNZSEE.50.4.482-493
C. Netrattana, R. Taleb, Hidekazu Watanabe, S. Kono, D. Mukai, M. Tani, M. Sakashita
The latest version of the Standard for Structural Calculation of Reinforced Concrete Structures, published by the Architectural Institute of Japan in 2010 [1], allows the design of shear walls with rectangular cross sections in addition to shear walls with boundary columns at the end regions (referred to here as “barbell shape”). In recent earthquakes, several reinforced concrete (RC) shear walls were damaged by flexural failures through concrete compression crushing accompanied with buckling of longitudinal reinforcement in the boundary areas. Damage levels have clearly been shown to be related to drift in structures; this is why drift limits are in place for structural design criteria. A crucial step in designing a structure to accommodate these drift limits is to model the ultimate drift capacity. Thus, in order to reduce damage from this failure mode, the ultimate drift capacity of RC shear walls needs to be estimated accurately. In this paper, a parametric study of the seismic behaviour of RC shear walls was conducted using a fibre-based model to investigate the influence of basic design parameters including concrete strength, volumetric ratio of transverse reinforcement in the confined area, axial load ratio and boundary column dimensions. This study focused on ultimate drift capacity for both shear walls with rectangular sections and shear walls with boundary columns. The fibre-based model was calibrated with experimental results of twenty eight tests on shear walls with confinement in the boundary regions. It was found that ultimate drift capacity is most sensitive to axial load ratio; increase of axial load deteriorated ultimate drift capacity dramatically. Two other secondary factors were: increased concrete strength slightly reduced ultimate drift capacity while increased shear reinforcement ratio and boundary column width improved ultimate drift capacity.
{"title":"Assessment of ultimate drift capacity of RC shear walls by key design parameters","authors":"C. Netrattana, R. Taleb, Hidekazu Watanabe, S. Kono, D. Mukai, M. Tani, M. Sakashita","doi":"10.5459/BNZSEE.50.4.482-493","DOIUrl":"https://doi.org/10.5459/BNZSEE.50.4.482-493","url":null,"abstract":"The latest version of the Standard for Structural Calculation of Reinforced Concrete Structures, published by the Architectural Institute of Japan in 2010 [1], allows the design of shear walls with rectangular cross sections in addition to shear walls with boundary columns at the end regions (referred to here as “barbell shape”). In recent earthquakes, several reinforced concrete (RC) shear walls were damaged by flexural failures through concrete compression crushing accompanied with buckling of longitudinal reinforcement in the boundary areas. Damage levels have clearly been shown to be related to drift in structures; this is why drift limits are in place for structural design criteria. A crucial step in designing a structure to accommodate these drift limits is to model the ultimate drift capacity. Thus, in order to reduce damage from this failure mode, the ultimate drift capacity of RC shear walls needs to be estimated accurately. In this paper, a parametric study of the seismic behaviour of RC shear walls was conducted using a fibre-based model to investigate the influence of basic design parameters including concrete strength, volumetric ratio of transverse reinforcement in the confined area, axial load ratio and boundary column dimensions. This study focused on ultimate drift capacity for both shear walls with rectangular sections and shear walls with boundary columns. The fibre-based model was calibrated with experimental results of twenty eight tests on shear walls with confinement in the boundary regions. It was found that ultimate drift capacity is most sensitive to axial load ratio; increase of axial load deteriorated ultimate drift capacity dramatically. Two other secondary factors were: increased concrete strength slightly reduced ultimate drift capacity while increased shear reinforcement ratio and boundary column width improved ultimate drift capacity.","PeriodicalId":343472,"journal":{"name":"Bulletin of the New Zealand National Society for Earthquake Engineering","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115254528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Kevin Spring (June 1933 – November 2016)","authors":"D. Brunsdon, Peter Clark","doi":"10.5459/BNZSEE.50.4.II","DOIUrl":"https://doi.org/10.5459/BNZSEE.50.4.II","url":null,"abstract":"","PeriodicalId":343472,"journal":{"name":"Bulletin of the New Zealand National Society for Earthquake Engineering","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130319944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-31DOI: 10.5459/BNZSEE.50.4.471-481
Yiqiu Lu, R. Henry
Recent earthquakes and research have shown that the minimum vertical reinforcement requirements in current concrete standards are insufficient to ensure well distributed cracking occurs in ductile reinforced concrete (RC) walls. To address the deficiencies of existing requirements, new theory was proposed to calculate the minimum distributed and end zone vertical reinforcement required for RC walls to meet current performance expectations. The distributed vertical reinforcement requirement was intended to prevent non-ductile behaviour for walls with low ductility demands, and was derived based on the requirement that nominal flexural strength must exceed the cracking moment capacity. The vertical reinforcement required in the ends of the wall was intended to ensure that well distributed secondary cracks form in the plastic hinge region of walls with high ductility demands, and was derived to ensure that the concrete tensile strength could be overcome by the tensile demands imposed when the vertical reinforcement in the ends of the wall yields. The proposed requirements considered the key parameters that influence the behaviour of walls with minimum vertical reinforcement. In addition, the proposed formulas were compared with current minimum vertical reinforcement limits from different concrete design standards by considering the margin of safety between cracking and nominal flexural strength and the secondary cracking behaviour. The deficiencies of the existing requirements were demonstrated and the proposed requirements were proved to be superior for walls with both low and high ductility demands.
{"title":"Minimum vertical reinforcement in RC walls","authors":"Yiqiu Lu, R. Henry","doi":"10.5459/BNZSEE.50.4.471-481","DOIUrl":"https://doi.org/10.5459/BNZSEE.50.4.471-481","url":null,"abstract":"Recent earthquakes and research have shown that the minimum vertical reinforcement requirements in current concrete standards are insufficient to ensure well distributed cracking occurs in ductile reinforced concrete (RC) walls. To address the deficiencies of existing requirements, new theory was proposed to calculate the minimum distributed and end zone vertical reinforcement required for RC walls to meet current performance expectations. The distributed vertical reinforcement requirement was intended to prevent non-ductile behaviour for walls with low ductility demands, and was derived based on the requirement that nominal flexural strength must exceed the cracking moment capacity. The vertical reinforcement required in the ends of the wall was intended to ensure that well distributed secondary cracks form in the plastic hinge region of walls with high ductility demands, and was derived to ensure that the concrete tensile strength could be overcome by the tensile demands imposed when the vertical reinforcement in the ends of the wall yields. The proposed requirements considered the key parameters that influence the behaviour of walls with minimum vertical reinforcement. In addition, the proposed formulas were compared with current minimum vertical reinforcement limits from different concrete design standards by considering the margin of safety between cracking and nominal flexural strength and the secondary cracking behaviour. The deficiencies of the existing requirements were demonstrated and the proposed requirements were proved to be superior for walls with both low and high ductility demands.","PeriodicalId":343472,"journal":{"name":"Bulletin of the New Zealand National Society for Earthquake Engineering","volume":"605 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116457844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-31DOI: 10.5459/BNZSEE.50.4.527-536
K. Kitayama, H. Katae
The seismic performance of a corner beam-column joint in reinforced concrete frames was studied by testing two three-dimensional corner beam-column subassemblage specimens without slabs under constant column axial load and bi-directional lateral cyclic load reversals. The column-to-beam flexural strength ratio was varied from 1.4 to 2.3 by changing the magnitude of column axial load. Although a sufficient margin to prevent shear failure was provided to a corner beam-column joint in the test, the subassemblage specimens failed in joint hinging after beam and column longitudinal bars and joint hoops yielded. The ultimate joint hinging capacity of a corner joint under bi-directional lateral loading was enhanced by an increase in column compressive axial load, and can be estimated based on the new mechanism proposed by Kusuhara and Shiohara. INTRODUCTION A new mechanism of joint hinging was proposed by Shiohara [1], a professor at the University of Tokyo, Japan, for a beamcolumn joint in reinforced concrete (RC) moment-resisting frames. The joint hinging mechanism is observed in laboratory tests when an ultimate flexural capacity of a column section is close to that of a beam section in an RC unit frame. A joint hinging model proposed by Kusuhara and Shiohara [2] is shown in Figure 1 for a plane exterior beam-column joint. An exterior beam-column subassemblage is divided into three elements; an upper column, a lower column and a beam. Each element rotates like a rigid body as shown in Figure 1, forming a principal diagonal crack along a diagonal compression strut in a joint and a short diagonal crack developing from a reentrant corner in a tesion side. Recent experimental studies to verify the joint hinging mechanism have been conducted using 2D plane interior [3] and exterior [4] beam-column subassemblage specimens. There are, however, few tests which use 3D beam-columnjoint subassemblages with orthogonal beams to each other which frame into a column such as a corner beam-column joint [5]. The previous study [5] dealt with not joint hinging failure, but beam flexural yielding. For corner columns in RC buildings, a loss of capacity to sustain column axial load resulting from severe damage to a corner joint has resulted in partial story collapse of the buildings in past earthquakes as illustrated in Figure 2 for the 1993 Guam Island Earthquake. The ultimate flexural capacity of a corner column frequently decreases during an earthquake because the axial load on the corner column cyclically increases and decreases by change of direction of lateral loads induced by earthquake excitations. Therefore, it is of great importance to investigate earthquake resistant performance of a corner beam-column joint subjected to tri-directional earthquake loading. Therefore the seismic performance of a corner beam-column joint in RC frames was studied, focusing on joint hinging mechanism, by testing two three-dimensional beam-column subassemblage specimens without slab
{"title":"Earthquake resistance of reinforced concrete corner beam-column joints with different column axial loads under bi-directional lateral loading","authors":"K. Kitayama, H. Katae","doi":"10.5459/BNZSEE.50.4.527-536","DOIUrl":"https://doi.org/10.5459/BNZSEE.50.4.527-536","url":null,"abstract":"The seismic performance of a corner beam-column joint in reinforced concrete frames was studied by testing two three-dimensional corner beam-column subassemblage specimens without slabs under constant column axial load and bi-directional lateral cyclic load reversals. The column-to-beam flexural strength ratio was varied from 1.4 to 2.3 by changing the magnitude of column axial load. Although a sufficient margin to prevent shear failure was provided to a corner beam-column joint in the test, the subassemblage specimens failed in joint hinging after beam and column longitudinal bars and joint hoops yielded. The ultimate joint hinging capacity of a corner joint under bi-directional lateral loading was enhanced by an increase in column compressive axial load, and can be estimated based on the new mechanism proposed by Kusuhara and Shiohara. INTRODUCTION A new mechanism of joint hinging was proposed by Shiohara [1], a professor at the University of Tokyo, Japan, for a beamcolumn joint in reinforced concrete (RC) moment-resisting frames. The joint hinging mechanism is observed in laboratory tests when an ultimate flexural capacity of a column section is close to that of a beam section in an RC unit frame. A joint hinging model proposed by Kusuhara and Shiohara [2] is shown in Figure 1 for a plane exterior beam-column joint. An exterior beam-column subassemblage is divided into three elements; an upper column, a lower column and a beam. Each element rotates like a rigid body as shown in Figure 1, forming a principal diagonal crack along a diagonal compression strut in a joint and a short diagonal crack developing from a reentrant corner in a tesion side. Recent experimental studies to verify the joint hinging mechanism have been conducted using 2D plane interior [3] and exterior [4] beam-column subassemblage specimens. There are, however, few tests which use 3D beam-columnjoint subassemblages with orthogonal beams to each other which frame into a column such as a corner beam-column joint [5]. The previous study [5] dealt with not joint hinging failure, but beam flexural yielding. For corner columns in RC buildings, a loss of capacity to sustain column axial load resulting from severe damage to a corner joint has resulted in partial story collapse of the buildings in past earthquakes as illustrated in Figure 2 for the 1993 Guam Island Earthquake. The ultimate flexural capacity of a corner column frequently decreases during an earthquake because the axial load on the corner column cyclically increases and decreases by change of direction of lateral loads induced by earthquake excitations. Therefore, it is of great importance to investigate earthquake resistant performance of a corner beam-column joint subjected to tri-directional earthquake loading. Therefore the seismic performance of a corner beam-column joint in RC frames was studied, focusing on joint hinging mechanism, by testing two three-dimensional beam-column subassemblage specimens without slab","PeriodicalId":343472,"journal":{"name":"Bulletin of the New Zealand National Society for Earthquake Engineering","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128141905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-12-31DOI: 10.5459/bnzsee.50.4.586-594
Toshikazu Kabeyasawa, T. Mukai, H. Fukuyama, H. Suwada, Hiroto Kato
Static loading tests on two full-scale reinforced concrete buildings were conducted at Building Research Institute in 2014 and 2015 to verify the effectiveness of damage control design utilizing walls. The tested buildings were five-storeys high with two bays in the direction of loading. The 2014 specimen was a moment resisting frame consisting of beams and columns with wing walls. The 2015 specimen contained wing walls, spandrels and hanging walls attached to the columns and beams. The measured strengths were much higher than the calculated strength of the bare frame without these walls. The hysteretic curves showed ductile behaviour in the 2014 specimen until ultimate drift, while strength deterioration was observed in the 2015 specimen. From the cracking pattern and the storey drift distributions within the specimens, the first specimen formed a beam sway mechanism, and the second specimen formed a mixed mechanism with column yielding between the 1 to 3 storeys. The residual cracks of the specimens were generally wider due to the concentration of the plastic hinge region, although the damage was evaluated as slight at 0.33% drift and as minor at 0.75% based on the residual energy capacity. Damage grades evaluated from the residual energy capacity were obviously smaller than the damage grades evaluated from the residual crack widths in accordance with the damage evaluation guidelines.
{"title":"Full-scale testing of reinforced concrete frame buildings with attached walls considering damage control design","authors":"Toshikazu Kabeyasawa, T. Mukai, H. Fukuyama, H. Suwada, Hiroto Kato","doi":"10.5459/bnzsee.50.4.586-594","DOIUrl":"https://doi.org/10.5459/bnzsee.50.4.586-594","url":null,"abstract":"Static loading tests on two full-scale reinforced concrete buildings were conducted at Building Research Institute in 2014 and 2015 to verify the effectiveness of damage control design utilizing walls. The tested buildings were five-storeys high with two bays in the direction of loading. The 2014 specimen was a moment resisting frame consisting of beams and columns with wing walls. The 2015 specimen contained wing walls, spandrels and hanging walls attached to the columns and beams. The measured strengths were much higher than the calculated strength of the bare frame without these walls. The hysteretic curves showed ductile behaviour in the 2014 specimen until ultimate drift, while strength deterioration was observed in the 2015 specimen. From the cracking pattern and the storey drift distributions within the specimens, the first specimen formed a beam sway mechanism, and the second specimen formed a mixed mechanism with column yielding between the 1 to 3 storeys. The residual cracks of the specimens were generally wider due to the concentration of the plastic hinge region, although the damage was evaluated as slight at 0.33% drift and as minor at 0.75% based on the residual energy capacity. Damage grades evaluated from the residual energy capacity were obviously smaller than the damage grades evaluated from the residual crack widths in accordance with the damage evaluation guidelines.","PeriodicalId":343472,"journal":{"name":"Bulletin of the New Zealand National Society for Earthquake Engineering","volume":"193 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125490301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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