Frame Height Research Articles

Strong-Back System Coupled with Framed Structure to Control the Building Seismic Response

In the present paper, the coupled behavior of structural systems obtained by connecting a moment resisting frame structure with a vertical elastic truss, known in the literature as strong-back, which acts as a mast by imposing to the structure a given lateral deformed shape, is investigated. The rigid behavior of the strong-back, which is designed in order to remain in the elastic field under strong seismic ground motion, imposes a uniform inter storey drift along the frame height, thus avoiding undesired effects such as soft storey and weak storey mechanisms. Consequently, the whole structural system may be, at first approximation, modelled as an equivalent Single Degree of Freedom system thus allowing for an analytical description of its response. In particular, in the work the attention is paid to the mutual actions exchanged by the strong-back and the frame by solving the static equilibrium equations, assuming a shear type behavior for the frame. Finally, some numerical simulations of frame systems with strong-back systems as subjected to earthquake ground motions are developed, encompassing both shear type frames and frames with flexible beams.

Parametric study on energy demands for steel special concentrically braced frames

Structures are designed in such a way that they behave in a nonlinear manner when subject to strong ground motions. Energy concepts have been widely used to evaluate the structural performance for the last few decades. Energy based design can be expressed as the balance of energy input and the energy dissipation capacity of the structure. New research is needed for multi degree of freedom systems (MDOFs)-real structures- within the framework of the energy based design methodology. In this paper, energy parameters are evaluated for low-, medium- and high-rise steel special concentrically braced frames (SCBFs) in terms of total energy input and hysteretic energy. Nonlinear dynamic time history analyses are carried out to assess the variation of energy terms along the height of the frames. A seismic energy demand spectrum is developed and hysteretic energy distributions within the frames are presented.

Analysis of strut-to-bone lengthening ratio for hexapod frames using mathematical modeling

Background: Hexapod external fixators often incorporate bone lengthening as part of a multi-planar deformity correction plan. The hexapod struts, however, do not distract in the direction of bone lengthening. Their oblique orientation to the ring creates a vector that is the summation of multiple individual strut adjustments. We demonstrate that a 1 mm lengthening of each of all six struts always created more than 1 mm of lengthening at the bone. Methods: The amount of lengthening was analyzed with the Taylor Spatial Frame™ (Smith and Nephew, Memphis, TN, USA) software using two different methods. Results: As the strut lengths got longer the ratio got closer to one but it never reached 1.0. Conclusions: This information is critical when using very short struts or very large rings. In these two scenarios, the Δ frame height relative to the Δ strut length becomes much greater than one. Clinical Relevance: A strut length much greater than one will cause the bone to lengthen much faster than the surgeon desires. It may also lead to unhealthy regenerate bone formation and could create delays in bone healing.

The Benslimane\u2019s Artistic Model for Females\u2019 Gaze Beauty: An Original Assessment Tool

BackgroundThe aim of this paper is to analyze the aesthetic characteristics of the human females’ gaze using anthropometry and to present an artistic model to represent it: “The Frame Concept.” In this model, the eye fissure represents a painting, and the most peripheral shadows around it represent the frame of this painting. The narrower the frame, the more aesthetically pleasing and youthful the gaze appears.Materials and MethodThis study included a literature review of the features that make the gaze appear attractive. Photographs of models with attractive gazes were examined, and old photographs of patients were compared to recent photographs. The frame ratio was defined by anthropometric measurements of modern portraits of twenty consecutive Miss World winners. The concept was then validated for age and attractiveness across centuries by analysis of modern female photographs and works of art acknowledged for portraying beautiful young and older women in classical paintings.ResultsThe frame height inversely correlated with attractiveness in modern female portrait photographs. The eye fissure frame ratio of modern idealized female portraits was similar to that of beautiful female portraits idealized by classical artists. In contrast, the eye fissure frames of classical artists’ mothers’ portraits were significantly wider than those of beautiful younger women.ConclusionThe Frame Concept is a valid artistic tool that provides an understanding of both the aesthetic and aging characteristics of the female periorbital region, enabling the practitioner to plan appropriate aesthetic interventions.Level of Evidence IIIThis journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the A3 online Instructions to Authors. www.springer.com/00266.

Period Formula for Reinforced Concrete Buildings with Infill Walls

The calculation of fundamental time period of vibration is a crucial step in seismic design and analysis of the structures to assess global response of the structure. Different international code proposed empirical expressions considering only height for bare frame structures and height and width of the buildings with infill to estimate the fundamental time period. This paper summaries the effect of the following parameters of building height, bay width, number of bays, cracked or un-cracked section of the structural member and support condition at the base on the fundamental time period of reinforced concrete bare frame and buildings with infill. Modal analysis of 360 building models with selected parameters is investigated in this study. A new equation, which is a function of the selected parameters (building height, bay width, number of bays, type of support condition, cracked or un-cracked sections and type of frame chosen for analysis) is also proposed using multiple linear regression analysis for predicting the fundamental period of buildings. The proposed simple model, including the building height, bay width, number of bays, type of support condition, cracked or un-cracked sections and type of frame chosen for analysis, showed better estimate in predicting the fundamental period of buildings compared to the code equations.

Seismic design and response of steel multi-tiered concentrically braced frames in Canada

This article investigates the seismic design and response of steel multi-tiered concentrically braced frames (MT-BFs) in which braces meet at columns between diaphragms. The seismic design provisions of CSA S16-14 are described and illustrated for three-tiered Type MD (moderately ductile) and five-tiered Type LD (limited ductile) braced frames. Analysis methods are proposed to evaluate the in-plane flexural demand on columns. The seismic response of the frames is examined through nonlinear response history analysis. As assumed in design, inelastic deformations tend to concentrate in one tier over the frame height, causing non-uniform drift demands and in-plane bending moments in the columns. CSA S16 provisions predicted well the frame in-plane flexural response and result in acceptable ductility demands on the braces. An extended seismic analysis and design approach that accounts for vertical distribution of brace tension yielding along the frame height is proposed for frames that exceed the limits prescribed in CSA S16.

Evaluating response modification factor (R) of reinforced concrete frames with chevron brace equipped with steel slit damper

Among the retrofitting techniques available, steel braces can be considered as one of the most efficient solution for seismic performance upgrading of RC frame structures. Added Damping and Stiffness (ADAS) elements are designed to dissipate energy thought the flexural yielding deformation of mild-steel plates. The current paper deals with the response ductility and the modification factors (R) of bare RC frames, RC frames with chevron steel braces, and RC frames with steel slit dampers (SSD). For this purpose three RC frames of 8, 12 and 20 stories were analyzed without considering the existence of dampers, then each frame equipped with a SSD was studied. A nonlinear pushover analysis was performed. The results show that the response modification factors of RC frames equipped with steel slit dampers is higher than the other systems. Also the effect of height of frame on the response modification factor was investigated.

Proposition of New Method for Quick Assessment of Maximum Beam Ductility in Steel Moment Frame under Higher Mode Effects

A simple equation to estimate beam maximum ductility (µθb) of regular steel structures under ordinary (i.e., without near fault effect) earthquakes is proposed. This equation is a function of period, number of span and global ductility. The proposed procedure enables the rapid assessment of beam plastic rotation of existing buildings and direct deformation-controlled seismic design of new ones. To prepare rational databank, a considerable number of steel MRF with different geometric configuration were analyzed using nonlinear static and dynamic procedure (NSP and NDP). The NSP is used to evaluate the plastic hinge sequencing, force and deformation demands over the height of frames. However, the NDP is applied to prepare databank of demands. The proposed relation is based on nonlinear regression of the results of thousands of NDP. The result of study shows that the µθb is significantly higher than interstory and global ductility. Furthermore, the higher modes effect is completely sensible on increase of rotation ductility in upper stories of high-rise buildings. Finally, the ability of calculating µθb with acceptable precision is the advantage of proposed relation. The result of the proposed relation then could be compared with acceptance criteria of FEMA356 and therefore the performance level would be indicated.

Analysis and Design of Two-Tiered Steel Braced Frames under In-Plane Seismic Demand

AbstractA seismic design strategy, which is intended to be implemented within the framework of the U.S. seismic design provisions for steel structures, is presented for single-story steel concentrically braced frames that are divided into two tiers. In this method, the columns are designed to resist the axial loads acting in combination with the in-plane flexural demand resulting from uneven distribution of brace inelastic deformations over the frame height. This design procedure, which establishes enhanced requirements beyond the 2010 edition of the U.S. seismic design provisions, prevents concentration of deformation in one tier and causes frame nonlinear deformation to be distributed between the tiers. The column bending moments depend on the story shear resistance that develops in each tier when the bracing members are at buckling and in the postbuckling range. The method also aims to control tier drifts to protect the bracing members from excessive inelastic demand, which could cause brace fracture. ...

Evaluation of the infill influence on the elastic period of existing RC frames

The common practice in civil engineering considers the infill as nonstructural elements, thus they are often neglected in the evaluation of the structural seismic behavior. However, the damages observed in past earthquakes around the world, have shown as the presence of infills significantly influence the seismic performance of Reinforced Concrete (RC) resisting frames.Several studies conducted in the last years emphasize the importance of infills on the evaluation of the elastic period of infilled frames; however the influence of mechanical properties of infills walls is often neglected.In this study the effect of infills in the seismic behavior of R.C. frames has been analyzed in terms of modal properties, namely evaluating the elastic period by means an eigenvalue analysis on 2D models. A parametric analysis has been performed taking into account the height of frames, the presence of flat/deep beams, the influence of infills Young modulus and the percentage of openings in the infills. Also the presence of setbacks in the frames has been considered. The numerical results provided useful information about the influence of masonry infill properties and allowed to define a new relationship to evaluate the elastic period of vibration.

Transcatheter Replacement of Failed Bioprosthetic Valves: Large Multicenter Assessment of the Effect of Implantation Depth on Hemodynamics After Aortic Valve-in-Valve.

Transcatheter valve implantation inside failed bioprosthetic surgical valves (valve-in-valve [ViV]) may offer an advantage over reoperation. Supra-annular transcatheter valve position may be advantageous in achieving better hemodynamics after ViV. Our objective was to define targets for implantation that would improve hemodynamics after ViV. Cases from the Valve-in-Valve International Data (VIVID) registry were analyzed using centralized core laboratory assessment blinded to clinical events. Multivariate analysis was performed to identify independent predictors of elevated postprocedural gradients (mean ≥20 mm Hg). Optimal implantation depths were defined by receiver operating characteristic curve. A total of 292 consecutive patients (age, 78.9±8.7 years; 60.3% male; 157 CoreValve Evolut and 135 Sapien XT) were evaluated. High implantation was associated with significantly lower rates of elevated gradients in comparison with low implantation (CoreValve Evolut, 15% versus 34.2%; P=0.03 and Sapien XT, 18.5% versus 43.5%; P=0.03, respectively). Optimal implantation depths were defined: CoreValve Evolut, 0 to 5 mm; Sapien XT, 0 to 2 mm (0-10% frame height); sensitivities, 91.3% and 88.5%, respectively. The strongest independent correlate for elevated gradients after ViV was device position (high: odds ratio, 0.22; confidence interval, 0.1-0.52; P=0.001), in addition to type of device used (CoreValve Evolut: odds ratio, 0.5; confidence interval, 0.28-0.88; P=0.02) and surgical valve mechanism of failure (stenosis/mixed baseline failure: odds ratio, 3.12; confidence interval, 1.51-6.45; P=0.002). High implantation inside failed bioprosthetic valves is a strong independent correlate of lower postprocedural gradients in both self- and balloon-expandable transcatheter valves. These clinical evaluations support specific implantation targets to optimize hemodynamics after ViV.

Predictors of Permanent Pacemaker Implantations and New-Onset Conduction Abnormalities With the SAPIEN 3 Balloon-Expandable Transcatheter Heart Valve.

This study investigates the influence of implantation depth and prosthesis oversizing on conduction abnormalities (CA) and permanent pacemaker implantation (PPI) after SAPIEN 3 (Edwards Lifesciences, Irvine, California) implantation. CA and PPIs are frequent complications after transcatheter aortic valve replacement with a next-generation balloon-expandable transcatheter heart valve (SAPIEN 3). The potential underlying mechanisms are incompletely understood. Of 244 patients treated with SAPIEN 3,208 without a previous pacemaker and 184 without baseline CA were analyzed. We assessed the association of angiographic implantation depth (% of frame height below the annulus) and degree of oversizing with PPI and CA. New PPI and new or worsened CA or PPI occurred in 16% (34 of 208) and 31% (57 of 184), respectively. Patients requiring PPI had a higher prevalence of atrial fibrillation (44% vs. 24%; p = 0.017), complete right bundle branch block (27% vs. 5%; p = 0.001), and bradycardia (<60 beats/min, 38% vs. 21%; p = 0.034). In patients with new CA or PPI, implantation depth was lower (at septal side: 29 ± 8% vs. 25 ± 7%; p = 0.003), and rate of oversizing was higher (19% [11 of 57] vs. 6% [8 of 126]; p = 0.007). Independent predictors of new or worsened CA or PPI were implantation depth at septal side (odds ratio [OR]: 1.063 [95% confidence interval (CI): 1.017 to 1.110]; p = 0.006 per % of frame below the aortic annulus), oversizing (OR: 3.489 [95% CI: 1.236 to 9.848]; p = 0.018), and QRS duration (OR: 1.033 [95% CI: 1.011 to 1.056]; p = 0.003 per ms). Implantation depth and prosthesis oversizing were associated with a higher rate of new CA or PPI using the SAPIEN 3. Thus, avoidance of deep implantation and extreme oversizing may reduce these complications.

Preparing the Fragility Curve of Semi-Rigid Beam-to-Steel Column Connection

Background/Objectives: Examination of the connections in a steel structure is of paramount importance and lack of precision in design and implementation of connections in steel structures will cause not only failure in the connection itself but also devastating effects on structural members and thereby entire the structure. Methods/Statistical Analysis: In present study, structural safety is assessed through probabilistic methods and the work mainly tries to make a suitable platform for its performance within the useful life of structure. To this end, the experimental setup for testing these connections - which are proper agents of their performance in a building frame (connection place and a half of joint beam and column) - was modeled in the software ABAQUS and acceleration time history of the frame it is embedded in is included under a set of certain records of the desired site. Results: Connection in a structure with a special frame and moderate height was studied and initially it was determined to join levels of performance with a suitable criteria based on connection failure. Thereafter, the corresponding fragility curves were drawn and then compared with moment-rotation curve and cyclic loading based on joining models which are influenced by nonlinear static analysis and cyclic loading. Conclusion/Application: Pushover and cyclic loading curves of this connection were determined in order to specify level of performance of the connection as per the connection failure.

Variation in mouthguard thickness according to heating conditions during fabrication Part 2: sheet shape and effect of thermal shrinkage.

The aim of this study was to investigate the influence of the thermal shrinkage to thickness of the mouthguard with the heating method by the setting position of a sheet and the working model using an ethylene vinyl acetate sheet prepared by extrusion. Mouthguards were fabricated with EVA sheets (4.0mm thick) using a vacuum-forming machine. Two forming conditions were compared: the square sheet was pinched by the clamping frame attached to the forming machine (S); and the round sheet was pinched at the top and bottom and stabilized by the circle tray (R). The sheet was aligned to make the sheet's extrusion direction vertical (V) or parallel (P) to the midline of the working model. The following two heating conditions were compared: (i) the sheet was molded when it sagged 15mm below the level of the sheet frame measured at the top of the post in condition S (S-0), or that sagged 10mm in condition R (R-0) in the usual position; (ii) the sheet frame was lowered by 50mm from the ordinary height (S-50, R-50). Postmolding thickness was determined using a measuring device. Measurement points were the incisal and molar portion. Differences in the change of thickness of mouthguards molded under different heating conditions and extrusion directions for each sheet shape were analyzed by two-way analysis of variance (anova). The results of this study showed that by lowering the height of the sheet frame, the difference of the sheet temperature of each part was reduced. Among all sheets, condition V produced under S-50 and R-50 had the largest thickness independently of shape sheet. Furthermore, thickness reduction is effectively suppressed by aligning the direction of the extruded sheet to be vertical to the midline of the model.

Gasometers: Cyril E. Power.

Gasometers, also called gas holders, were large tanks for storing coal gas and maintaining pressure in distribution lines. In Great Britain, gas holders were common features of the industrial landscape before natural gas became the primary source of fuel for powering streetlights and heating homes. They were often constructed at the sites of gasworks, which manufactured coal gas by carbonizing coal. Although many gas holders are still standing, most are no longer in use. Some gas holders were enclosed in steel cages called guide frames, as seen inGasometers, amonotype print by the British architect and printmaker Cyril E. Power (1872-1951). In this image, the gas holder is the red cylinder in the lower right corner. Gas holders were designed so that the upperpart of the tanknested in the lowerpart andexpandedvertically to accommodate increases in pressure. The height of theguide frames in thispicture indicates themaximumheight of expansion. Power, whose first career was architecture,

다양한 SDC와 높이를 갖는 철골 중간모멘트 골조의 내진성능평가

Steel intermediate moment frames (IMF) have been widely used as a seismic force resisting system in regions of low and moderate seismicity. In this study, the seismic collapse performance of the steel IMFs designed according to current seismic code was evaluated. For this purpose, seventeen steel IMFs were designed according to seismic design codes (ASCE 7-10 and AISC 360-10), and the probability of collapse for these frames are estimated. The probability of collapse of steel IMFs became larger with an increases in the height of frames. And the probability of collapse of steel IMFs also became larger as the level of SDC is higher. Several IMFs designed according to current seismic design codes did not satisfy the acceptance criteria specified in FEMA P-695.

Seismic evaluation of vertically irregular building frames with stiffness, strength, combined-stiffness-and-strength and mass irregularities

In this paper, the effects of different types of irregularity along the height on the seismic responses of moment resisting frames are investigated using nonlinear dynamic analysis. Furthermore, the applicability of consecutive modal pushover (CMP) procedure for computing the seismic demands of vertically irregular frames is studied and the advantages and limitations of the procedure are elaborated. For this purpose, a special moment resisting steel frame of 10-storey height was selected as reference regular frame for which the effect of higher modes is important. Forty vertically irregular frames with stiffness, strength, combined-stiffness-and-strength and mass irregularities are created by applying two modification factors (MF=2 and 4) in four different locations along the height of the reference frame. Seismic demands of irregular frames are computed by using the nonlinear response history analysis (NL-RHA) and CMP procedure. Modal pushover analysis (MPA) method is also carried out for the sake of comparison. The effect of different types of irregularity along the height on the seismic demands of vertically irregular frames is investigated by studying the results obtained from the NL-RHA. To demonstrate the accuracy of the enhanced pushover analysis methods, the results derived from the CMP and MPA are compared with those obtained by benchmark solution, i.e., NL-RHA. The results show that the CMP and MPA methods can accurately compute the seismic demands of vertically irregular buildings. The methods may be, however, less accurate especially in estimating plastic hinge rotations for weak or weak-and-soft top and middle storeys of vertically irregular frames.

Seismic Fragility Curves for Steel and Reinforced Concrete Frames Based on Near-Field and Far-Field Ground Motion Records

This study presents the fragility curve for steel and concrete frames based on near-field (NF) and far-field (FF) ground motion records. The fragility curve is calibrated to the incremental dynamic analysis (IDA) curve based on building materials and frame heights. The frames are designed according to Eurocodes. This study uses seven ground motion records for NF and another seven records for FF. The five performance levels prescribed by FEMA-273 are used as structure performance benchmarks in generating the IDA curve. Results based on the NF and FF records indicate that a three-storey steel frame is stiffer than a concrete frame. By contrast, the results for a six-storey structure show that a steel frame is more suitable than low-rise and mid-rise frames. The fragility curve results show that the probability of reaching or exceeding a specified damage state can be determined.

The Use of Outrigger System in Steel Plate Shear Wall Structures

The use of capacity design method (CDM) in steel plate shear wall (SPSW) structures results in large vertical boundary elements (VBEs). One way to reduce the force demands on VBEs is to employ outrigger beams in the adjacent spans of SPSW. In this paper, twelve dual SPSW-moment resisting frames are designed and analyzed by FE method to investigate the effects of outrigger system on the behavior of SPSW structures. Results show that outrigger beams can transfer considerable amount of axial force and bending moment from VBEs to the outer spans columns; resulting in smaller sections for VBEs. In addition, the most effective stories to employ outrigger beams are shown to be the stories which undergo larger drifts. Outrigger system also results in a more uniform distribution of structural stiffness along the height of SPSW frames. Furthermore, a design procedure based on the direct analysis method is proposed for the design of SPSW-Outrigger system. The procedure eliminates the excessive capacities in CDM, while satisfying all CDM requirements.

Comparative Study on Seismic Response of Reinforced Concrete Frames with SMA in Column and Beam Plastic Hinge Zones

This paper presents a comparative analytical study on seismic response of low rise three storeys concrete frame reinforced with super-elastic material as rebar elements. The super-elastic shape memory alloy rebars were used as reinforcement in two plastic hinge zones of the frame, beam plastic hinge zones and column plastic hinge zones. The response of the frame structure with two different reinforced cases is compared to response of the frame structure reinforced with regular steel material. Nonlinear dynamic time history analysis is performed in this study. Three different great earthquake ground motions were used to determine the seismic response of the frame structures in terms of frame top displacement time history and inter-storey drift along the frame height for different cases of reinforcements. Results obtained from the analysis show that the seismic response of low rise frame reinforced with super-elastic SMA rebars is affected by the zone of which SMA rebar are used in reinforcement. The SMA column reinforcement is more effective than SMA beam reinforcement in reducing the frame response.