• Steel and Composite Structures
• /
• 제19권2호
• /
• pp.277-292
• /
• 2015

Previous research has shown that steel plate shear walls (SPSWs) are efficient lateral force-resisting systems against both wind and seismic loads. A properly designed SPSW can have high initial stiffness, strength, and energy absorption capacity as well as superior ductility. SPSWs have been commonly designed with unstiffened and stiffened infill plates based on economical and performance considerations. Recent introduction and application of corrugated plates with advantageous structural features has motivated the researchers to consider the employment of such elements in stiffened SPSWs with the aim of lowering the high construction cost of such high-performing systems. On this basis, this paper presents results from a numerical investigation of the hysteretic performance of SPSWs with trapezoidally corrugated infill plates. Finite element cyclic analyses are conducted on a series of flat- and corrugated-web SPSWs to examine the effects of web-plate thickness, corrugation angle, and number of corrugation half-waves on the hysteretic performance of such structural systems. Results of the parametric studies are indicative of effectiveness of increasing of the three aforementioned web-plate geometrical and corrugation parameters in improving the cyclic response and energy absorption capacity of SPSWs with trapezoidally corrugated infill plates. Increasing of the web-plate thickness and number of corrugation half-waves are found to be the most and the least effective in adjusting the hysteretic performance of such promising lateral force-resisting systems, respectively. Findings of this study also show that optimal selection of the web-plate thickness, corrugation angle, and number of corrugation half-waves along with proper design of the boundary frame members can result in high stiffness, strength, and cyclic performances of such corrugated-web SPSWs.

• Earthquakes and Structures
• /
• 제22권2호
• /
• pp.121-135
• /
• 2022

Many public buildings such as schools, hospitals, etc., where partial infill walls are present in reinforced concrete (RC) structures, have undergone undesirable damage/failure attributed to captive column effect during a moderate to severe earthquake shaking. Often, the situation gets worsened when these RC frames are non-ductile in nature, thus reducing the deformable capability of the frame. Also, in many parts of the Indian subcontinent, it is mandatory to use fly-ash bricks for construction so as to reduce the burden on the disposal of fly-ash produced at thermal power plants. In some scenario, when the non-ductile RC frame, partially infilled by fly-ash bricks, suffers major structural damage, the challenge remains on how to retrofit and restore it. Thus, in this study, two full-scale one-bay, one-story non-ductile RC frame models, namely, bare frame and RC partially infilled frame with fly-ash bricks in 50% of its opening area are considered. In the previous experiments, these models were subjected to slow-cyclic displacement-controlled loading to replicate damage due to a moderate earthquake. Now, in this study these damaged frames were retrofitted and an experimental investigation was performed on the retrofitted specimens to examine the effectiveness of the proposed retrofitting scheme. A hybrid retrofitting technique combining epoxy injection grouting with an innovative and easy-to-implement steel jacketing technique was proposed. This proposed retrofitting method has ensured proper confinement of damaged concrete. The retrofitted models were subjected to the same slow cyclic displacement-controlled loading which was used to damage the frames. The experimental study concluded that the hybrid retrofitting technique was quite effective in enhancing and regaining various seismic performance parameters such as, lateral strength and lateral stiffness of partially fly-ash brick infilled RC frame. Thus, the steel jacketing retrofitting scheme along with the epoxy injection grouting can be relied on for possible repair of the structural members which are damaged due to the captive column effect during the seismic shaking.

• 한국농촌건축학회논문집
• /
• 제16권2호
• /
• pp.1-8
• /
• 2014

In the past, Korea was classified as a region not affected by earthquakes. However, recent increase of earthquakes has forced to strengthen standards of earthquake resistant designs of structures to minimize seismic damage. In addition, it was thought that masonry infill walls in buildings are only acting as partitions, so these walls are not considered in analyzing building structures. But it was found that when seismic loads are applied to a structure with masonry infill walls, the walls affect the structure. Accordingly, this study conducted nonlinear static analyses for a structure constructed before applying earthquake resistant designs in two cases: when considering masonry walls and when not. The result showed that the seismic performance of the structure is insufficient. Thus, the structural resistance of the structure was also studied in two cases: when reinforcing with steel plate braces and when using carbon fiber braces. In the two cases reinforcing two different stiffeners, it was appeared that the behaviors of the structure were similar, though the cross-section area of a carbon fiber brace used to reinforcing the structure is only 12.6% of a steel plate brace, and its weight is only 2.8%. Thus, the reinforcing effect of the thin, light-weighted carbon fiber brace is much larger than that of the steel plate brace, when considering usability and constructability of both materials.

• 한국주거학회:학술대회논문집
• /
• 한국주거학회 2008년 추계학술발표대회 논문집
• /
• pp.479-482
• /
• 2008

The purpose of this study is a proposal about the flexibility of the performance category to revitalize the "Housing Performance Grading Indication System". This system consists of 5 main performance parts, 14 performance categories and 20 detailed performance lists. 5 main performance parts are Noise and Acoustics(Light-weight impact sound control, heavy-weight impact sound control, sound control of toilet, sound control of party wall), Long-life(flexibility, remodeling & maintenance, durability), Landscape & Indoor Environment(landscape, formaldehyde control& ventilation, daylighting, thermal environment), Welfare & Barrier-free(playground and community center, welfare space, barrier-free design), Fire Safety(fire safety, safe place, fire-resisting quality). The flexibility of the performance category is conformed to Long-life housing related grading and can realize the Long-life housing in response to resident needs about the space rearrangement. Now, The flexibility of the performance category is limited to the evaluation of the private space, that is, the Skeleton evaluation. This study would suggest alternatives to improve uppermost limits through analyzing 60 examples from January 9th 2009 to October 30th 2008. The flexibility of the performance category is possible to estimate not only the Skeleton evaluation but also the Infill evaluation in response to social changes.

• Coupled systems mechanics
• /
• 제5권2호
• /
• pp.127-144
• /
• 2016

Two dimensional numerical investigations were carried out to study the influence of interface thickness and their pattern on the behavior of reinforced concrete frames subjected to in-plane lateral loads using commercial finite element tool SAP 2000. The linear elastic analysis was carried out on one and two bay structural systems as well as the influence of number of stories was studied by varying the number of stories as single, three and five. The cement mortar was used as interface material and their effect was studied by varying thicknesses as 6, 8, 10, 14 and 20 mm. The interface was recognized as one sided, two sided, three sided and four sided and their effect was studied by removing the interface material between the reinforced concrete frame and masonry infill. The effect of lateral loads on infill masonry wall was also studied by varying assumed loads as 10, 20, 30, 40, 50 and 60 kN. The behavior of infilled frames studied has revealed that there is a maximum influence of interface thickness and interface pattern corresponding to 10 mm thickness. In general, the lateral displacement of frame is increased linearly with increase in lateral loads.

• Earthquakes and Structures
• /
• 제9권5호
• /
• pp.999-1028
• /
• 2015

Despite the fact that the fundamental period appears to be one of the most critical parameters for the seismic design of structures according to the modal superposition method, the so far available in the literature proposals for its estimation are often conflicting with each other making their use uncertain. Furthermore, the majority of these proposals do not take into account the presence of infills walls into the structure despite the fact that infill walls increase the stiffness and mass of structure leading to significant changes in the fundamental period numerical value. Toward this end, this paper presents a detailed and indepth analytical investigation on the parameters that affect the fundamental period of reinforce concrete structure. The calculated values of the fundamental period are compared against those obtained from the seismic code and equations proposed by various researchers in the literature. From the analysis of the results it has been found that the number of storeys, the span length, the stiffness of the infill wall panels, the location of the soft storeys and the soil type are crucial parameters that influence the fundamental period of RC buildings.

• Earthquakes and Structures
• /
• 제9권2호
• /
• pp.281-303
• /
• 2015

The effects of infill panels on the response of r.c. frames subjected to seismic action are widely recognized. Numerous experimental investigations were effected and several analytical models were developed on this subject. This work, which is part of a larger project dealing with specific materials and structures commonly used in Italy, discusses experimental tests on masonry and samples of bare and infilled portals. The experimental activity includes tests on elemental materials, and 12 wall samples. Finally, three one-bay one-story reinforced concrete frames, designed according to the outdated Italian technical code D.M. 1996 without seismic details, were tested (bare and infilled) under constant vertical and cyclic lateral load. The first cracks observed on the framed walls occurred at a drift of about 0.3%, reaching its maximum capacity at a drift of 0.5% while retaining its capacity up to a drift of 0.6%. Infill contributed to both the stiffness and strength of the bare reinforced concrete frame at small drifts thus improving overall system behavior. In addition to the experimental activities, previously mentioned, the recalibration of a model proposed by Comberscue (1996) was evaluated. The accuracy of an OpenSees non linear fiber based model of the prototype tested, including a strut element was verified through a comparison with the final experimental results. This work has been partially supported by research grant DPC-ReLUIS 2014.

• Steel and Composite Structures
• /
• 제42권1호
• /
• pp.123-137
• /
• 2022

The fundamental period (FP) is one of the most critical parameters for the seismic design of structures. In the reinforced concrete (RC) infilled frame, the infill walls significantly affect the FP because they change the stiffness and mass of the structure. Although several formulas have been proposed for estimating the FP of the RC infilled frame, they are often associated with high bias and variance. In this study, an efficient soft computing model, namely the group method of data handling (GMDH), is proposed to predict the FP of regular RC infilled frames. For this purpose, 4026 data sets are obtained from the open literature, and the quality of the database is examined and evaluated in detail. Based on the cleaning database, several GMDH models are constructed and the best prediction model, which considers the height of the building, the span length, the opening percentage, and the infill wall stiffness as the input variables for predicting the FP of regular RC infilled frames, is chosen. The performance of the proposed GMDH model is further underscored through comparison of its FP predictions with those of existing design codes and empirical models. The accuracy of the proposed GMDH model is proven to be superior to others. Finally, explicit formulas and a graphical user-friendly interface (GUI) tool are developed to apply the GMDH model for practical use. They can provide a rapid prediction and design for the FP of regular RC infilled frames.

• Steel and Composite Structures
• /
• 제33권1호
• /
• pp.19-36
• /
• 2019

Cyclic behaviour of composite (steel-concrete) plate shear walls (CPSW) with variable column flexural stiffness is experimentally and numerically investigated. The investigation included design, fabrication and testing of three pairs of one-bay one-storey CPSW specimens. The reference specimen pair was designed in way that its column flexural stiffness corresponds to the value required by the design codes, while within the other two specimen pairs column flexural stiffness was reduced by 18% and 36%, respectively. Specimens were subjected to quasi-static cyclic tests. Obtained results indicate that column flexural stiffness reduction in CPSW does not have negative impact on the overall behaviour allowing for satisfactory performance for up to 4% storey drift ratio while also enabling inelastic buckling of the infill steel plate. Additionally, in comparison to similar steel plate shear wall (SPSW) specimens, column "pull-in" deformations are less pronounced within CPSW specimens. Therefore, the results indicate that prescribed minimal column flexural stiffness value used for CPSW might be conservative, and can additionally be reduced when compared to the prescribed value for SPSWs. Furthermore, finite element (FE) pushover simulations were conducted using shell and solid elements. Such FE models can adequately simulate cyclic behaviour of CPSW and as such could be further used for numerical parametric analyses. It is necessary to mention that the implemented pushover FE models were not able to adequately reproduce column "pull-in" deformation and that further development of FE simulations is required where cyclic loading of the shear walls needs to be simulated.

• 국제강구조저널
• /
• 제18권4호
• /
• pp.1210-1218
• /
• 2018

A new type of earthquake-resisting element that consists of a steel plate shear wall with slits is introduced. The infill steel plate is divided into a series of vertical flexural links with vertical links. The steel plate shear walls absorb energy by means of in-plane bending deformation of the flexural links and the energy dissipation capacity of the plastic hinges formed at both ends of the flexural links when under lateral loads. In this paper, finite element analysis and experimental studies at low cyclic loadings were conducted on specimens with steel plate shear walls with multilayer slits. The effects caused by varied slit pattern in terms of slit design parameters on lateral stiffness, ultimate bearing capacity and hysteretic behavior of the shear walls were analyzed. Results showed that the failure mode of steel plate shear walls with a single-layer slit was more likely to be out-of-plane buckling of the flexural links. As a result, the lateral stiffness and the ultimate bearing capacity were relatively lower when the precondition of the total height of the vertical slits remained the same. Differently, the failure mode of steel plate shear walls with multilayer slits was prone to global buckling of the infill steel plates; more obvious tensile fields provided evidence to the fact of higher lateral stiffness and excellent ultimate bearing capacity. It was also concluded that multilayer specimens exhibited better energy dissipation capacity compared with single-layer plate shear walls.