• Steel and Composite Structures
• /
• v.51 no.5
• /
• pp.487-498
• /
• 2024

Steel moment resisting frames (MRFs) typically have inter-story drift concentrations at lower stories during earthquakes as found from previous research. Hinged walls (HWs) can be used as structural strengthening components to force the MRFs deform uniformly along the building height. However, large moment demands are often observed on HWs and make the design of HWs non-economical. This paper proposes a method to reduce the moment demand on HWs using a ductile connection system between the MRFs and the HWs. The ductile connection system is designed with a yield strength and energy dissipation capacity, for the purpose of limiting the seismic forces transferred to the HWs and dissipating seismic energy. Nonlinear time history analyses were performed using 10 far-filed earthquakes at maximum considered earthquake level. The analysis results show that the proposed ductile connection system can reduce: (1) seismic moment demands in the HWs; (2) floor accelerations; (3) the connection force between HWs and MRFs.

• Proceedings of the KSR Conference
• /
• 1998.11a
• /
• pp.47-53
• /
• 1998

Many kinds of methods have been developed to carry out transverse analysis of prestressed concrete(PSC) box girder bridges. However, most bridge engineers only use the simple frame model to analyze PSC box girder in transverse direction because of its simplicity and easy usage. But, this frame model has many problems such that it can't consider warping, distortion and longitudinal load distribution. In this study, the results from simple frame model and 3-dimensional shell model with UIC load are compared to show its validity. The results from frame model are slightly larger than those of shell model in symmetric loading case. But, positive bending moment of top slab is larger in shell model than frame model in case subject to anti-symmetric loading. It shows that simple frame model can't always give conservative results, so a practical tool whose treatment is easy and whose product is reliable shall be developed as soon as possible.

• Journal of Korean Society of Steel Construction
• /
• v.11 no.1 s.38
• /
• pp.69-78
• /
• 1999

When the lateral forces are applied to a frame, columns in the frame are usually accompanied with sidesway. If this sidesway is large, the frame is subjected to buckling and an early yielding of members which reduces the overall frame stiffness. In this study, numerical analysis of frames were conducted to evaluate the ultimate lateral strength of steel moment resisting frames permitted to sidesway under axial and lateral forces, and develope the procedure for determining the limits of column slenderness ratios. In the numerical analysis, the effects of the relative stiffness ratio between beam and column, deterioration of overall frame stiffness, slenderness ratio and loading conditions were considered. The elasto-plastic analysis method in which the $P-{\Delta}$effect is implemented, presented by the author previously, was adopted in the analysis. Incremental lateral forces were applied to the frame under constant axial loads and the generalized inverse is employed for the post-ultimate behavior.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.41 no.4
• /
• pp.113-120
• /
• 2004

In this paper, we propose an efficient feature extraction and image retrieval algorithm for content-based retrieval method. First, we extract the object using Gaussian edge detector for input image which is key frames of MPEG video and extract the object features that are location feature, distributed dimension feature and invariant moments feature. Next, we extract the characteristic color feature using the proposed HAQ(Histogram Analysis md Quantization) algorithm. Finally, we implement an retrieval of four features in sequence with the proposed matching method for query image which is a shot frame except the key frames of MPEG video. The purpose of this paper is to propose the novel content-based image retrieval algerian which retrieves the key frame in the shot boundary of MPEG video belonging to the scene requested by user. The experimental results show an efficient retrieval for 836 sample images in 10 music videos using the proposed algorithm.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.20 no.5
• /
• pp.18-25
• /
• 2016

This research purposed to study a structural effect on curtailment of upper shear wall in frame-shear wall structures, using MIDAS-Gen. In this study, the analysis variables were the story number of curtailment of upper shear wall, change of column section in every 2 stories and change of shear wall thickness in every 2 stories. In order to analyse a structural effect on curtailment of upper shear wall in frame-shear wall structures, we studied the distribution of shear force and overturning moment according to curtailment of shear wall, the inflection point of shear wall from shear force/overturning moment and the lateral stiffness. The results of study proposed the quantitative influence that the curtailment of upper shear wall in frame-shear wall structures had on the structural performance such as lateral stiffness. Furthermore, it is verified that the results of study can be very helpful in catching the materials on the structure design for a reasonable frame-shear wall system.

• Earthquakes and Structures
• /
• v.19 no.1
• /
• pp.59-77
• /
• 2020

The code static eccentricity model for elastic torsional design of structures has two critical shortcomings: (1) the negation of the inertial torsional moment at the center of mass (CM), particularly for torsionally-unbalanced (TU) building structures, and (2) the confusion caused by the discrepancy in the definition of the design eccentricity in codes and the resistance eccentricity commonly used by engineers such as in FEMA454. To overcome these shortcomings, using the resistance eccentricity model that can accommodate the inertial torsional moment at the CM, interactive relations between shear and torsion are proposed as follows: (1) elastic responses of structures at instants of peak edge-frame drifts are given as functions of resistance eccentricity, and (2) elastic hysteretic relationships between shear and torsion in forces and deformations are bounded by ellipsoids constructed using two adjacent dominant modes. Comparison of demands estimated using these two interactive relations with those from shake-table tests of two TU building structures (a 1:5-scale five-story reinforced concrete (RC) building model and a 1:12-scale 17-story RC building model) under the service level earthquake (SLE) show that these relations match experimental results of models reasonably well. Concepts proposed in this study enable engineers to not only visualize the overall picture of torsional behavior including the relationship between shear and torsion with the range of forces and deformations, but also pinpoint easily the information about critical responses of structures such as the maximum edge-frame drifts and the corresponding shear force and torsion moment with the eccentricity.

• Earthquakes and Structures
• /
• v.12 no.5
• /
• pp.529-541
• /
• 2017

According to the definition, progressive collapse could occur due to the initial partial failure of the structural members which by spreading to the adjacent members, could result in partial or overall collapse of the structure. Up to now, most researchers have investigated the progressive collapse due to explosion, fire or impact loads. But new research has shown that the seismic load could also be a factor for initiation of the progressive collapse. In this research, the progressive collapse capacity for the 5 and 15-story steel special moment resisting frames using push-down nonlinear static analysis, and nonlinear dynamic analysis under the gravity loads specified in the GSA Guidelines, were studied. After identifying the critical members, in order to investigate the seismic progressive collapse, the 5-story steel special moment resisting frame was analyzed by the nonlinear time history analysis under the effect of earthquakes with different characteristics. In order to account for the initial damage, one of the critical columns was weakened at the initiation of the earthquake or its Peak Ground Acceleration (PGA). The results of progressive collapse analyses showed that the potential of progressive collapse is considerably dependent upon location of the removed column and the number of stories, also the results of seismic progressive collapse showed that the dynamic response of column removal under the seismic load is completely dependent on earthquake characteristics like Arias intensity, PGA and earthquake frequency contents.

• Earthquakes and Structures
• /
• v.15 no.3
• /
• pp.319-334
• /
• 2018

In this paper, an analytical study was carried out to propose an optimum base-isolated system for the design of steel structures equipped with lead rubber bearings (LRB). For this, 5 and 10-storey steel moment resisting frames (MRFs) were designed as Special Moment Frame (SMF). These two-dimensional and three-bay frames equipped with a set of isolation systems within a predefined range that minimizes the response of the base-isolated frames subjected to a series of earthquakes. In the design of LRB, two main parameters, namely, isolation period (T) and the ratio of strength to weight (Q/W) supported by isolators were considered as 2.25, 2.5, 2.75 and 3 s, 0.05, 0.10 and 0.15, respectively. The Force-deformation behavior of the isolators was modelled by the bi-linear behavior which could reflect the nonlinear characteristics of the lead-plug bearings. The base-isolated frames were modelled using a finite element program and those performances were evaluated in the light of the nonlinear time history analyses by six natural accelerograms compatible with seismic hazard levels of 2% probability of exceedance in 50 years. The performance of the isolated frames was assessed in terms of roof displacement, relative displacement, interstorey drift, absolute acceleration, base shear and hysteretic curve.

• Steel and Composite Structures
• /
• v.37 no.5
• /
• pp.571-587
• /
• 2020

In this article the seismic demand and performance of two recent braced steel frames named steel moment frames with the elliptic bracing (ELBRFs) are assessed through a laboratory program and numerical analyses of FEM. Here, one of the specimens is without connecting bracket from the corner of the frame to the elliptic brace (ELBRF-E), while the other is with the connecting brackets (ELBRF-B). In both the elliptic braced moment resisting frames (ELBRFs), in addition to not having any opening space problem in the bracing systems when installed in the surrounding frames, they improve structure's behavior. The experimental test is run on ½ scale single-story single-bay ELBRF specimens under cyclic quasi-static loading and compared with X-bracing and SMRF systems in one story base model. This system is of appropriate stiffness and a high ductility, with an increased response modification factor. Moreover, its energy dissipation is high. In the ELBRF bracing systems, there exists a great interval between relative deformation at the yield point and maximum relative deformation after entering the plastic region. In other words, the distance from the first plastic hinge to the collapse of the structure is fairly large. The experimental outcomes here, are in good agreement with the theoretical predictions.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.27 no.4
• /
• pp.215-222
• /
• 2014

The objective of this research is to evaluate the seismic performance of steel intermediate moment frames(IMFs) with different heights. The seimic performance is conducted according to ATC-63. Three-, six, nine- and twelve-story IMFs are designed according to KBC 2009. The connection is modeled to have a drift capacity of 0.02rad, which is required for IMF connections. This study shows that the probability of collapse increases with an increase in the height of the frame. Nine- and twelve-story frames did not satisfy the requirement specified in ATC-63.