Multi-performance blast pressure-duration curves of laminated glass panes

2020 ◽  
pp. 204141962096883
Author(s):  
Mohammadreza Eslami ◽  
Khalid M Mosalam ◽  
Venkatesh Kodur ◽  
Shalva Marjanishvili ◽  
Brian Katz ◽  
...  
Keyword(s):  
Blast Resistance ◽  
Design Procedure ◽  
Performance Criteria ◽  
Laminated Glass ◽  
Limit States ◽  
Performance Levels ◽  
Performance Pressure ◽  
Pull Out ◽  
Aspect Ratios ◽  
Ultimate Failure

The current design procedure for blast resistant glass panes is based on dynamic analysis of idealized SDOF models under simplified triangular impulse loads or code-specified pressure-duration (pressure-impulse) curves. In both cases, the main objective is to prevent failure of the pane with no explicit consideration of other limit states to reach higher performance levels. In this study, multi-performance pressure-duration curves of Laminated Glass (LG) panes are estimated by accurate pre-validated Finite Element (FE) models. Multiple performance criteria including initial cracking, PVB-50% (maximum polyvinyl butyral, i.e. PVB, interlayer strain of 50%), PVB-100% (maximum PVB interlayer strain of 100%), and ultimate failure of the pane are considered and pressure-duration curves are estimated for each of these performance levels. Ultimate failure of the pane can be either due to rupture of the PVB interlayer or pull-out of the pane from its frame. Multi-performance pressure-duration curves are obtained for 18 different LG panes with three different layups, two widths, and three aspect ratios. According to the obtained results, the thickness of the glass layers has more pronounced contribution to the blast resistance of the panes in all limit states compared with the PVB thickness. Moreover, the ultimate failure mode of the LG panes with thicker PVB interlayer is observed to be typically pull-out of the pane rather than PVB rupture. Therefore, these panes require frames with deeper bites to develop their full blast resistance. Finally, the blast performance of the LG panes are compared with that of Thermally Tempered Glass (TTG) panes to shed more light on the superior blast resistance of LG panes.

Pull-Out Performance of T-Stub End Plate Connected To Concrete Filled Thin-Walled Steel Tube (CFTST) using Lindapter Hollo-Bolts

2018 ◽  
Vol 15 (1) ◽  
pp. 59
Author(s):  
NAZRUL AZMI AHMAD ZAMRI ◽  
CLOTILDA PETRUS ◽  
AZMI IBRAHIM ◽  
HANIZAH AB HAMID
Keyword(s):  
Limit Load ◽  
Steel Tube ◽  
Limit States ◽  
End Plate ◽  
Pull Out ◽  
Pullout Load ◽  
Thin Walled ◽  
Stub End ◽  
Concrete Filled Steel Tubes ◽  
Ultimate Limit

The application of concrete filled steel tubes (CFSTs) as composite members has widely been used around the world and is becoming popular day by day for structural application especially in earthquake regions. This paper indicates that an experimental study was conducted to comprehend the behaviour of T-stub end plates connected to concrete filled thin-walled steel tube (CFTST) with different types of bolts and are subjected to pullout load. The bolts used are normal type bolt M20 grade 8.8 and Lindapter Hollo-bolt HB16 and HB20. A series of 10 mm thick T-stub end plates were fastened to 2 mm CFTST of 200 mm x 200 mm in cross-section. All of the specimens were subjected to monotonic pull-out load until failure. Based on test results, the Lidapter Hollo-bolts showed better performance compare to normal bolts. The highest ultimate limit load for T-stub end plate fasten with Lindapter Hollo-bolt is four times higher than with normal bolt although all end plates show similar behaviour and failure mode patterns. It can be concluded that T-stub end plate with Lindapter Hollo-bolt shows a better performance in the service limit and ultimate limit states according to the regulations in the design codes.

scholarly journals μ-Synthesis for Fractional-Order Robust Controllers

Mathematics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 911
Author(s):  
Vlad Mihaly ◽  
Mircea Şuşcă ◽  
Dora Morar ◽  
Mihai Stănese ◽  
Petru Dobra
Keyword(s):  
Control Problem ◽  
Fractional Order ◽  
Design Procedure ◽  
High Order ◽  
Numerical Control ◽  
Performance Criteria ◽  
Iteration Algorithm ◽  
Optimization Approach ◽  
Cnc Machine ◽  
Bee Colony

The current article presents a design procedure for obtaining robust multiple-input and multiple-output (MIMO) fractional-order controllers using a μ-synthesis design procedure with D–K iteration. μ-synthesis uses the generalized Robust Control framework in order to find a controller which meets the stability and performance criteria for a family of plants. Because this control problem is NP-hard, it is usually solved using an approximation, the most common being the D–K iteration algorithm, but, this approximation leads to high-order controllers, which are not practically feasible. If a desired structure is imposed to the controller, the corresponding K step is a non-convex problem. The novelty of the paper consists in an artificial bee colony swarm optimization approach to compute the nearly optimal controller parameters. Further, a mixed-sensitivity μ-synthesis control problem is solved with the proposed approach for a two-axis Computer Numerical Control (CNC) machine benchmark problem. The resulting controller using the described algorithm manages to ensure, with mathematical guarantee, both robust stability and robust performance, while the high-order controller obtained with the classical μ-synthesis approach in MATLAB does not offer this.

Influence of Human Error on Structural Reliability

2017 ◽  
Author(s):  
Eric Brehm ◽  
Robert Hertle ◽  
Markus Wetzel
Keyword(s):  
Human Error ◽  
Structural Reliability ◽  
Failure Modes ◽  
Structural Model ◽  
Limit State ◽  
Design Procedure ◽  
Material Strength ◽  
Limit States ◽  
The Impact

In common structural design, random variables, such as material strength or loads, are represented by fixed numbers defined in design codes. This is also referred to as deterministic design. Addressing the random character of these variables directly, the probabilistic design procedure allows the determination of the probability of exceeding a defined limit state. This probability is referred to as failure probability. From there, the structural reliability, representing the survival probability, can be determined. Structural reliability thus is a property of a structure or structural member, depending on the relevant limit states, failure modes and basic variables. This is the basis for the determination of partial safety factors which are, for sake of a simpler design, applied within deterministic design procedures. In addition to the basic variables in terms of material and loads, further basic variables representing the structural model have to be considered. These depend strongly on the experience of the design engineer and the level of detailing of the model. However, in the clear majority of cases [1] failure does not occur due to unexpectedly high or low values of loads or material strength. The most common reasons for failure are human errors in design and execution. This paper will provide practical examples of original designs affected by human error and will assess the impact on structural reliability.

scholarly journals Different Suture Materials for Arthroscopic Transtibial Pull-out Repair of Medial Meniscal Posterior Root Tears: A Human Biomechanical Study

2019 ◽  
Vol 7 (9) ◽  
pp. 232596711987327
Author(s):  
Gilberto Y. Nakama ◽  
Zachary S. Aman ◽  
Hunter W. Storaci ◽  
Alexander S. Kuczmarski ◽  
Joseph J. Krob ◽  
...  
Keyword(s):  
Medial Meniscus ◽  
Failure Load ◽  
Clinical Care ◽  
Posterior Root ◽  
Clinical Failure ◽  
Postoperative Rehabilitation ◽  
Pull Out ◽  
Ultimate Failure Load ◽  
Ultimate Failure ◽  
Suture Tape

Background: Transtibial pull-out repair of the medial meniscal posterior root (MMPR) has been largely assessed through biomechanical studies. Biomechanically comparing different suture types would further optimize MMPR fixation and affect clinical care. Purpose/Hypothesis: The purpose of this study was to determine the optimal suture material for MMPR fixation. It was hypothesized that ultra high–molecular weight polyethylene (UHMWPE) suture tape would be biomechanically superior to UHMWPE suture and standard suture. Study Design: Controlled laboratory study. Methods: The MMPR attachment was divided in 24 human cadaveric knees and randomly assigned to 3 repair groups: UHMWPE suture tape, UHMWPE suture, and standard suture. Specimens were dissected down to the medial meniscus, and the posterior root attachments were sectioned off the tibia. Two-tunnel transtibial pull-out repair with 2 sutures, as determined by the testing group, was performed. The repair constructs were cyclically loaded between 10 and 30 N at 0.5 Hz for 1000 cycles to mimic the forces experienced on the medial meniscus during postoperative rehabilitation. Displacement was recorded at 1, 50, 100, 500, and 1000 cycles. Ultimate failure load, displacement at failure, and load at 3 mm of displacement (clinical failure) were also recorded. Results: UHMWPE suture tape had significantly less displacement of the medial meniscus when compared with standard suture at 1 (–0.22 mm [95% CI, –0.41 to –0.02]; P = .025) and 50 (–0.35 mm [95% CI, –0.67 to –0.03]; P = .029) cycles. There were no other significant differences observed in displacement between groups at any number of cycles. UHMWPE suture tape had significantly less displacement at the time of failure than standard suture (–3.71 mm [95% CI, –7.17 to –0.24]; P = .034). UHMWPE suture tape had a significantly higher load to reach the clinical failure displacement of 3 mm than UHMWPE suture (15.64 N [95% CI, 0.02 to 31.26]; P = .05). There were no significant differences in ultimate failure load between groups. Conclusion: The meniscal root repair construct with UHMWPE suture tape may be stronger and less prone to displacement than that with standard suture or UHMWPE suture. Clinical Relevance: UHMWPE suture tape may provide better clinical results compared with UHMWPE suture and standard suture.

New Bolted End-Plate Connection Design

2014 ◽  
Vol 1025-1026 ◽  
pp. 878-884
Author(s):  
Jong Wan Hu ◽  
Jun Hyuk Ahn
Keyword(s):  
Design Procedure ◽  
High Strength ◽  
Limit States ◽  
Moment Connections ◽  
End Plate ◽  
Plastic Strength ◽  
Plate Connections ◽  
Plate Connection ◽  
Connection Design

This paper is principally performed to survey end-plate connection are described in the next part based on ideal limit states. The determination of end-plate based on the full plastic strength of the steel beam in accordance with 2001 AISC-LRFD manual and AISC/ANSI 358-05 Specifications. The bolted connections considered herein were performed to include the end-plate component of moment connections. This study is intended to investigate economic design for end-plate connections. In addition, the proposed end-plate model is evaluated by comparing the required factored bolt strength. The end-plates using 8 high strength bolts with wider gages demonstrated this design. The equations belonging to the step-by-step design procedure are described based on complete proving of design. Finally, new design methodology is applied to end-plate connections suggested in this study.

Seismic retrofit of structures using rotational friction dampers with restoring force

2020 ◽  
Vol 23 (16) ◽  
pp. 3525-3540
Author(s):  
Asad Naeem ◽  
Jinkoo Kim
Keyword(s):  
Ground Motions ◽  
Design Procedure ◽  
Steel Structures ◽  
Friction Damper ◽  
Heavy Duty ◽  
Limit States ◽  
Restoring Force ◽  
Friction Dampers ◽  
Torsional Spring ◽  
Capacity Spectrum

In this study, the seismic performance of a rotational friction damper with restoring force is presented. The torsional spring friction damper consists of rotational friction pads with the heavy duty torsional springs attached on both sides of the friction damper. An analytical model and a design procedure for the damper are developed using capacity spectrum method. A parametric study is carried out to investigate the influence of the torsional spring in the response of the structure when subjected to ground motions. The seismic performances of steel structures retrofitted with the torsional spring friction damper and conventional rotational friction dampers are evaluated using fragility analysis, which shows that the structure retrofitted with the torsional spring friction damper has the smallest probability of reaching the specific limit states.

Blast test and numerical simulation of point-supported glazing

2016 ◽  
Vol 19 (12) ◽  
pp. 1841-1854 ◽  
Author(s):  
Suwen Chen ◽  
Chen-Guang Zhu ◽  
Guo-Qiang Li ◽  
Yong Lu
Keyword(s):  
Numerical Simulation ◽  
Failure Mode ◽  
Failure Modes ◽  
Blast Resistance ◽  
Polyvinyl Butyral ◽  
Laminated Glass ◽  
Curtain Wall ◽  
Blast Response ◽  
Glass Panels ◽  
Glass Curtain Wall

The blast resistance of point-supported laminated glass curtain wall has been investigated by means of field blast tests and numerical simulation. Nine site blast tests were carried out, considering two types of glass thickness and six TNT charges ranging from 0.4 to 30 kg. The overpressure and displacement time histories were measured and the failure modes were observed. The overpressure obtained from the measurement panel exhibited a typical pattern of near-field blast with a steep increase followed by a rapid decay within a few milliseconds. The displacement response of the laminated glass panels increased with the increase in the TNT charge almost linearly in the smaller tests (scaled distance ranging 4.5–7 m/kg1/3), which was in line with the increase in the blast impulse in these tests. The failure mode of the point-supported laminated glass panels was featured by tearing off of the polyvinyl butyral layer around the support area, while the glass shards still adhered to the polyvinyl butyral interlayer. Nonlinear dynamic finite element simulation agrees reasonably well with the results from the blast tests. Severe stress concentration has been predicted to occur at the rim of the support holes, leading to initiation of failure at these supports, and this also agrees with the failure mode observed from the blast test. Finally, parametric studies are carried out to investigate the influence of TNT charge weight and the geometric parameters of the panel on the blast response of the glass curtain wall.

An Evaluation of Two-Level Seismic Design Procedure

1993 ◽  
Vol 9 (1) ◽  
pp. 121-135 ◽  
Author(s):  
Chia-Ming Uang
Keyword(s):  
Structural Damage ◽  
Limit State ◽  
Design Procedure ◽  
Reduction Factor ◽  
Performance Criteria ◽  
Ultimate Limit State ◽  
Seismic Codes ◽  
Seismic Force ◽  
Force Reduction Factor ◽  
Force Reduction

The two-level design philosophy is recognized by modern seismic codes. When this philosophy is implemented in the code, the intensities of the two design earthquakes, the structural performance criteria, explicit versus implicit design approach, and the effectiveness to achieve the performance criteria vary considerably from one code to the other. For the ultimate limit state, the UBC was compared with seismic codes of Canada, Japan, and Eurocode. It was found that a trend to deviate from the UBC approach of using a single seismic force reduction factor (i.e., Rw) is apparent. Instead, an approach using a compound force reduction factor which considers the contribution of structural ductility and structural overstrength is preferred. For the serviceability limit state, a comparison of the level of design earthquakes and performance criteria of the UBC, Tri-Services Manual, and the Japanese code indicates that the UBC produces the most flexible structure, and that UBC does not control structural damage. It is suggested that the UBC adopts an explicit serviceability design procedure.

scholarly journals Application of Direct Displacement Based Design of Reinforced Concrete Frames Subjected to Earthquake Loads

2020 ◽  
Vol 8 (5) ◽  
pp. 5153-5160
Keyword(s):  
Response Spectrum ◽  
Design Procedure ◽  
Time History ◽  
Building Design ◽  
Life Safety ◽  
Nonlinear Time History Analysis ◽  
Performance Levels ◽  
Collapse Prevention ◽  
Direct Displacement Based Design ◽  
Displacement Based

Numerous studies are reported in literature on performance evaluation and rehabilitation of building however, limited studies are reported on performance based design of new buildings. Displacement based design procedure is a new method which is not available in Indian building design codes. An effort has been done to investigate the Direct Displacement Based Design (DDBD) for four, eight and twelve story regular RC frame buildings proposed by Priestley et al, using Indian code Response Spectrum for Zone V which is considered as a very high intensity seismic risk zone for life safety and collapse prevention performance levels. Nonlinear time history analysis is carried out for available ground motion and compared with the performance levels (in terms of drift, displacement). Observations show that design displacement reduction factor should be different for life safety and collapse prevention levels. The effective damping increases as the height of the building increases and is higher for collapse prevention.

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