Resistant Frames Research Articles

Seismic Analysis of a Ten-Storey Reinforced Concrete Building in Jazan Area, KSA

Jazan area is located in the most active seismic zone region of the Kingdom of Saudi Arabia where there is a complicated geological structures and tectonics. This project reviews the seismic activities occurred in Jazan area together with reviewing the Saudi Building (Seismic) Code (SBC-301-2007) [1]. A multi-story reinforced concrete building, in Jazan city, was seismically analyzed using the Equivalent Lateral Force Procedure with the aid of STAAD PRO software. The building, which was Ordinary Reinforced Concrete Moment Resisting Frame (ORCMRF), was analyzed in compliance with the provisions of (SBC-301-2007) [1]. The most important parameters governing the analysis of this frame were dead load, live load and seismic loads. Seismic loads were computed as pairs of accelerations versus times. The damping ratio was taken as 0.05 (5% of the critical damping). The ground accelerations versus time periods were calculated using SBC-301-2007 together with parameters necessary to be used as input data for the program to calculate the seismic parameters, i.e., reactions, displacements, base shear, bending moments, shearing forces, drifts. The obtained results show effects of earthquake ground motions on building studied herein are so greater for the higher increases of the values of outputs resulting from seismic loads comparing to that due to static load only. Finally, the results obtained, clearly, show the importance of taking the Saudi seismic code provisions into account when analyzing and designing multi-story buildings in Jazan area.

Experimental and Numerical Investigation of IPE Reduced Beam Sections with Diagonal Web Stiffeners

A reduced beam section (RBS) is a new type of connection in steel moment resistant frames. In addition to the major benefits, RBS has its own weaknesses, such as web local buckling and lateral torsional buckling. The purpose of this paper is to improve the performance of European I-beam profile (IPE) with an arched cut in the flange, using a diagonal stiffener of the beam web. With the help of laboratory tests and numerical models, it was found that the use of a diagonal stiffener in the area of an arched cut increased the energy dissipation and plastic rotation capacity of RBS connection.

Development of Drift-Based Damage Index for Reinforced Concrete Moment Resisting Frames with Setback

One kind of the irregularities in structures, with considerable effect on seismic performance, is setback in elevation that causes large damage especially in the vicinity of the irregularity. The main objective of this research is to propose and develop drift-based index to estimate damage to reinforced concrete moment resisting frames with setback. For this purpose, first, inelastic dynamic time-history analysis is performed on several frames with different types of setbacks subjected to various earthquake records and damage to them is computed by the Park–Ang damage index. Then, the two relations between the damage and drift are derived by applying irregularity indices to account for setback effects. It is shown that the proposed damage indices are capable to estimate the damage index of setback frames.

Evaluation of collapse-resistance of special truss moment frames as per FEMAp695 approach

Special Truss Moment Resisting Frame (STMF) is one of the lateral force-resisting systems in which the input seismic energy is allowed to dissipate at the predefined special regions of the steel truss members. Past studies have shown that STMFs designed based on the prescriptive force-based design method recommended by the current codes as well as the performance-based plastic design (PBPD) method have shown to achieve the desired performance levels in terms of the target drift and yield mechanisms under Design-basis earthquake (DBE) hazard level. However, there is a need to evaluate their collapse-resistance potential of such systems under the extreme earthquake loading conditions. In this study, the collapse performance of a mid-rise nine-story STMFs designed based on the current code (ASCE) procedure as well as PBPD method has been investigated in accordance with the FEMAp695 recommendations. The collapse margin ratio computed for both ASCE and PBPD STMFs using the nonlinear incremental dynamic analyses under the amplified levels of seismic hazards has been compared with the recommended values. Finally, a progressive collapse analysis has been conducted for the PBPD STMF to investigate its load redistribution potential under a column-removal scenario.

Introducing the innovative post-tensioned connection with the rigid steel node

Securing strength, stiffness, and ductility in connections is one of the most important goals in structural design. After the Northridge earthquake, most steel moment resistant frames were damaged due to sudden fractures in beam-to-column connections. This resulted in the reconsideration of connection design and performance. As an alternative to weld connections, some researchers proposed the implementation of post-tensioned connections. In the present paper, the innovative connection is a combination of high strength steel frames which, through a rigid steel node above and below the beam flanges, provide the required stiffness, strength and ductility. Advantages of this connection include self-centering capability, lack of residual deformations, and energy dissipation which are analyzed using numerical and experimental methods. The modeling procedure and the cyclic behavior of the connection are studied and the analytical and the experimental results are compared. The results show that the cyclic responses observed in numerical simulations are in agreement with those from the experimental task and that the connection is superior to conventional moment resisting connections. The assumptions employed in simplifying simulations demonstrated high accuracy revealing an improvement in the seismic behavior of the connection.

Structural redundancy of 3D RC frames under seismic excitations

The components of the seismic behavior factor of RC frames are expected to change as structural redundancy increases. Most researches indicate that increasing redundancy is desirable in response to stochastic events such as earthquake loading. The present paper investigated the effect of redundancy on a fixed plan for seismic behavior factor components and the nonlinear behavior of RC frames. The 3D RC moment resistant frames with equal lateral resistance were designed to examine the role of redundancy in earthquake-resistant design and to distinguish it from total overstrength capacity. The seismic behavior factor and dynamic behavior of structures under natural strong ground motions were numerically evaluated as the judging criteria for structural seismic behavior. The results indicate that increasing redundancy alone in a fixed plan cannot be defined as a criterion for improving the structural seismic behavior.

DRIFT DEMANDS OF LOW-DUCTILE MOMENT RESISTANCE FRAMES (MRF) UNDER FAR FIELD EARTHQUAKE EXCITATIONS

Most of current Malaysian’s structures have not been designed with consideration of seismic excitation effect. Tremors that have been recorded locally due to active local faults and earthquake events in neighboring countries have raised the question about the level of safety of these structures. The effects of seismic excitation on the stability and fragility of the structures are now being concerned by most researchers and engineers in order to mitigate structural damage and societal losses. This study focuses on the seismic performance of Reinforced Concrete (RC) Moment Resistance Frames (MRF) in Malaysia which has been only designed to resist gravity and wind loads effects. An ordinary building layout with different number of stories (four, seven, and 10 stories) is selected in a way that can represent the potential of soft-story phenomenon in RC buildings in Malaysia. Such structures have limited lateral load capacity to withstand against strong ground motion. Nonlinear time history analysis is used to analyze the structures using seven different ground motions scaled to 0.05g, 0.1g and 0.15g to suit Malaysian condition. The outcomes of this study illustrate the vulnerability of the typical RC, MRF structures in Malaysia to soft-story phenomenon and clarify on the necessity of seismic retrofit for such structures.

Evaluation of Progressive Collapse Resistance of Multi-Storey RC Building by Linear Static Analysis Method

Collapse of building due to gas explosion or due to bombing has been occurred in past. Due to explosion a local load carrying member fails and the load carried by failed member get transferred as extra loads to adjacent members which are generally not designed for that, due to extra loads adjacent members gets failed in such a manner whole building collapses. Due to increase in terrorist activity Progressive collapse resistance buildings are need of present and future. In this work resistance to progressive collapse of 12 storey RC Special Moment resistance frame building having 7 and 5 bays each of 4.5 m in X and Y direction respectively has been evaluated by Linear Static Analysis method. Each is of 3 m height and General Service Administration (GSA) guild lines has been followed for analysis procedure. Four Column removal case each at one time has been analyzed and DCR ratio has been calculated and compared with limiting value provided by GSA 2013. DCR values for different column removal cases also has been compared and final conclusion has been made.

Stability of Concrete Moment Resisting Frames in View of Current Codes Requirements

Stability of Concrete Moment Resisting Frames in View of Current Codes Requirements

Design guides to resist progressive collapse for steel structures

The progressive collapse phenomenon in structures has been interested by civil engineers and the building standards organizations. This is particularly true for the tall and special buildings ever since local collapse of the Ronan Point tower in UK in 1968. When initial or secondary defects of main load carrying elements, overloads or unpredicted loads occur in the structure, a local collapse may be arise that could be distributed through entire structure and cause global collapse. One is not able to prevent the reason of failure as well as the prevention of propagation of the collapse. Also, one is not able to predict the start point of collapse. Therefore we should generalize design guides to whole or the part of structure based on the risk analysis and use of load carrying elements removal scenario. There are some new guides and criteria for elements and connections to be designed to resist progressive collapse. In this paper, codes and recommendations by various researchers are presented, classified and compared for steel structures. Two current design methods are described in this paper and some retrofitting methods are summarized. Finally a steel building with special moment resistant frame is analyzed as a case study based on two standards guidelines. This includes consideration of codes recommendations. It is shown that progressive collapse potential of the building depends on the removal scenario selection and type of analysis. Different results are obtained based on two guidelines.

Matrix attachment regions included in a bicistronic vector enhances and stabilizes follistatin gene expressions in both transgenic cells and transgenic mice

In the present study, follistatin (FST) gene expression vectors with either a bicistronic gene transfer cassette alone, or a bicistron gene cassette carrying a matrix attachment region (MAR) were constructed and transfected to bovine fetal fibroblasts. Evaluations of both the integration and expression of exogenous FST indicated that the pMAR-CAG-FST-IRES-AcGFP1-polyA-MAR (pMAR-FST) vector had higher capacity to form mono- clonal transgenic cells than the vector without MAR, though transient transfection and integration efficiency were similar with either construct. Remarkably, protein expression in transgenic cells with the pMAR-FST vector was significantly higher than that from the bicistronic vector. Exogenous FST was expressed in all of the pMAR- FST transgenic mice at F0 ,F 1 and F2. Total muscle growth in F0 mice was significantly greater than in wild-type mice, with larger muscles in fore and hind limbs of transgenic mice. pMAR-FST transgenic mice were also found with more evenly distributed muscle bundles and thinner spaces between sarcolemma, which suggests a correlation between transgene expression-associated muscle develop- ment and the trend of muscle growth. In conclusion, a pMAR-FST vector, which excluded the resistant genes and frame structure, enhances and stabilizes FST gene expressions in both transfected cells and transgenic mice.

Finite Element Analysis of Self-centering Moment Resistant Frames with and without Steel Plate Shear Wall

The Northridge earthquake on January 1994 damaged a large number of buildings all through Los Angeles. The most recurrent pattern of structural damage was the brittle failures at beam column junction in steel moment-resisting frames (MRF's)[6] This event brought out the need for further improving the Moment Resistant Frames and its connections. A new system of Moment Resisting Frames (MRF) commonly known as Self-Centering Moment Resisting Frames (SC-MRF) was developed. These designs are capable of resisting the seismic loads without sustaining much damage. The paper studies the behaviour of Self-Centering Moment Resisting Frames (SC-MRF) with and without steel plate shear walls subjected to cyclic loading. A detailed three dimensional finite element modeling using plate elements available in ANSYS FEA code is done. Geometric and material nonlinear stress analysis of the frame and a detailed comparison of the frame with and without steel plate shear walls is done. It can be observed that the sway of the SC-MRF frame is much higher than that of a conventional frame, but by introducing a thin steel plate shear wall this deformation can be brought down to a much lower value.

Seismic Performance Evaluation of Multistory Reinforced Concrete Moment Resisting Frame Structure with Shear Walls

This paper is intended to evaluate the seismic performance of a twelve-story reinforced concrete moment-resisting frame structure with shear walls using 3D finite element models according to such seismic design regulations as Federal Emergency Management Agency (FEMA) guideline and seismic building codes including Los Angeles Tall Building Structural Design Council (LATBSDC) code. The structure is located in Seismic Zone 4, considered the highest-seismic-risk classification established by the U.S. Geological Survey. 3D finite element model was created in commercially available finite element software. As part of the seismic performance evaluation, two standard approaches for the structure seismic analysis were used; response spectrum analysis and nonlinear time-history analysis. Both approaches were used to compute inter-story drift ratios of the structure. Seismic fragility curves for each floor of the structure were generated using the ratios from the time history analysis with the FEMA guideline so as to evaluate their seismic vulnerability. The ratios from both approaches were compared to FEMA and LATBSDC limits. The findings revealed that the floor-level fragility mostly decreased for all the FEMA performance levels with an increase in height and the ratios from both approaches mostly satisfied the codified limits.

Determining the Determination: Some Reflections on the Figure of the Two in the Discourse of Emancipation

This paper discusses the modalities of emancipation in contemporary theoretical discourses and shows that the persistent critique of the figure of the Two is problematic because it relies on a faulty assumption that a dualistic structure is necessarily metaphysical and therefore unfitting for the discourse of emancipation. My analysis draws on the works of Alain Badiou and Frantz Fanon in hopes of demonstrating the possibility of a non-metaphysical framing of resistance in terms of the Two. Both Badiou and Fanon affirm the prescriptive function of politics and insist that genuine change or decolonization must be of the order of production. For both, the prescriptive function of politics is structured in binary terms, except that its binarism is figured as a subjective Two rather than an objective Two. In this newly configured space of prescriptive politics, political struggle is able to redetermine the initial determination, thereby changing the representational regime governing the world. In the final analysis, to avoid the political ineffectiveness intrinsic to the action/reaction model of resistance, their solution is not to invent a third term but to think the beyond from within the Two, provided that this Two is radically reconceptualized as the subjective Two.

Analysis of the Effect of the Solid-Brick Infilled Frames on the Behavior of A Hybrid System of Moment Resistance Frame, Shear Wall, and Infilled Frame Along High Concrete Structures

This paper is to investigate the benefits of a new structural system (hereafter it is referred as “Ultra Hybrid System”) in high concrete buildings relying on the compound performance of the moment resistance frame, shear wall and infilled frame. In this case, the Ultra Hybrid System takes the advantage of the moment resistance frame and shear wall up to the height, where the wall performance reaches zero, while it is applied the infilled frame along with it. It is studied the system behavior based on using concrete-brick infilled frames in the upper floors to find out the interaction between the shear wall and infilled frame. Then, it is compared displacement, relative floor displacement, base shear, axial column loads in a hybrid system of the moment resistance frame and shear wall and the Ultra Hybrid System of the moment resistance frame, shear wall, and infilled frame. In this study, ETABS 2000 software package )Barkhordari et al., 2001) is used to model the system in compression diagonal mode. Finally, the results are presented in diagrams and tables.

The influence of binder rheological properties on asphalt mixture permanent deformation

The main goal of this paper is to propose the performance parameter for binder which is good for quality prediction of asphalt mixture in frame of resistance to permanent deformation (rutting). Additionally, correlation between, proposed by the authors, repeatable shear creep-recovery test carried out on binder and bituminous mixture rutting test is under evaluation. The results are analysed and correlation between the proposed functional parameter and rut depth is shown. Thanks to that it is possible to claim that expensive rutting test procedure can be assisted with simple test carried out in dynamic shear rheometer at the initial mix design procedure.

Development of the performance based plastic design for steel moment resistant frame

This paper presents the development of performance based plastic design (PBPD) method for steel moment frames with considering the gravity loads and P-Δ effects. In this method the design lateral forces are obtained from energy-work balance equation by using pre-selected target drift and yield mechanism. For further improvement of PBPD method, some solutions are represented to precisely obtain the required moment of columns in order to prevent their yielding that leads to form undesirable mechanisms in the structure. In order to show more validity of PBPD method, two model frames, 5 and 10story, are designed based on PBPD as well as elastic design method. The mentioned frames are evaluated by extensive nonlinear static pushover analysis and dynamic analysis. The results show that the frames designed by PBPD method reach the intended performance objectives in terms of yield mechanism and target drift levels. In contrast, the frame designed by Ed method experience large story drifts due to flexural yielding of the columns. Since PBPD method is a direct design method, little or no evaluation are needed after the initial design because the nonlinear behavior is built into the design process from the start.

Africa and Afrocentric Historicism: A Critique

Since the dawn of slavery in America, black activists have used Africa to construct a countervailing frame of resistance to oppression. Africa had functioned both as the justification for enslavement and racial discrimination for the dominant white society, and as the counter-hegemonic weapon of resistance and empowerment for blacks. Reacting to subordination and marginalization, modern black intellectuals, borrowing from the past, have equally invoked Africa in their quest for a useable and instrumental historical past with which to counteract the Eurocentric constructions of their heritage and experiences. However, the resultant Afrocentric historicist framing of Africa, as well as its racialized and essentialist character, had only replicated precisely the negative shortcomings of the Eurocentric historiography and black intellectuals were attempting to debunk.

Monolayer Cable-Stayed Steel Moment Resistant Frame and its Lateral Force Resisting Performance

A new lateral force resisting system (LFRS), referred to as the monolayer cable-stayed steel moment resistant frame (MCSMRF) system, is proposed in order to improve capacity of original MRF system and reduce lateral displacement of the system effectively. The MCSMRF integrates the respective advantages of both the steel moment resistant frame (MRF) and inclined cables, Likewise, the CSMRF renders both the dual seismic defense line and self-centering capacity. The working mechanism of the CSMRF are introduced. Secondly, the floor displacement (relative to the ground) approximation formula is developed for the MCSMRF under the lateral loading. Eventually, the numerical analysis is made of the MCSMRF with resorting to the developed approximation formula. The results show that the interstorey drift and the floor displacement significantly reduce with respect to the original steel MRF. Approximate calculation formula of elastic floor displacements can provide a theoretical basis for the preliminary design of its components.

SOIL-RAFT FOUNDATION-STRUCTURE INTERACTION EFFECTS ON SEISMIC PERFORMANCE OF MULTI-STORY MRF BUILDINGS

Recent studies show that the effects of Soil Structure Interaction (SSI) may be detrimental to the seismic response of structure and neglecting SSI in analysis may lead to un-conservative design. Despite this, the conventional design procedure usually involves assumption of fixity at the base of foundation neglecting the flexibility of the foundation, the compressibility of soil mass and consequently the effect of foundation settlement on further redistribution of bending moment and shear force demands. The effects of SSI are analyzed for typical multi-story building resting on raft foundation. Three methods of analysis are used for seismic demands evaluation of the target moment resistant frame buildings: equivalent static load (ESL); response spectrum (RS) methods and nonlinear time history (TH) analysis with suit of nine time history records. Three-dimensional Finite Element (FE) model is constructed to analyze the effects of different soil conditions and number of stories on the vibration characteristics and seismic response demands of building structures. Numerical results obtained using soil structure interaction model conditions are compared to those corresponding to fixed-base support conditions. The peak responses of story shear, story moment, story displacement, story drift, moments at beam ends, as well as force of inner columns are analyzed.