Deck System Research Articles

Cross-entropy-based cost-efficient 4D trajectory generation for airborne conflict resolution

Considering the transformation in roles of existing air traffic management technologies, future flight operations and flight deck systems will need additional avionics and operational procedures that involve adaptive algorithms and advanced decision support tools. The main purpose of this article is to provide a theoretical framework for tactical 4D-trajectory planning and conflict resolution of an aircraft equipped with novel automation tools. The proposed 4D-trajectory-planning method uses recent algorithmic advances in both probabilistic and deterministic methods to fully benefit from both approaches. We have constructed an aircraft performance model based on Base of Aircraft Data 4 with high-level hybrid flight template automatons and low-level flight maneuver automatons. This multi-modal flight trajectory approach is utilized to generate cost-efficient local trajectory segments instead of solving complex trajectory-generation problems globally. The proposed sampling-based trajectory planning algorithm spatially explores the airspace and provides proper separation through local trajectory segments and guarantees asymptotic optimality under certain conditions. Moreover, we have integrated the cross-entropy method, which transforms the sampling problem into a stochastic optimization problem, rapidly converges on the minimum cost trajectory sequence by utilizing available flight plans, and reduces the amount of sampling. The integration of the proposed strategies lets us solve challenging, real-time in-tactical 4D-trajectory planning problems within the current and the envisioned future realm of air traffic management systems.

Use of Markov Chain Model Based on Actual Repair Status to Predict Bridge Deterioration in Shanghai, China

Bridge condition prediction is crucial in preparing conservation budgets for the maintenance of bridges. A bridge management system has been formally used and promoted for urban bridge management in Shanghai, China, since 2004, and 16,623 bridge records have been accumulated. Although there are many data records, predicting bridge deterioration precisely is difficult because the data composition is complicated and the maintenance history is varied. Therefore a Markov chain model was applied as a decision aid to consider the different conservation strategies. More than 66,000 data records were used to calibrate the model. The modeling considered two conservation regimes: ( a) routine maintenance and minor repair and ( b) medium and major repair. The repair rate was obtained through an actual conservation survey. The influence of spatial distribution was also considered. Bridge conservation efforts were uneven at the city level. The condition of bridges in the central city is much better than that of those in suburban areas, although the proportion (55.6%, 2014) of suburban bridges is larger. Furthermore, based on the present status of bridges, conservation efforts have been insufficient generally and even worse in suburban areas. The medium and major repair levels have had a significant impact on deck systems and superstructure but quite a small impact on substructure and the whole bridge. Thus the present conservation efforts cannot improve the overall bridge condition fundamentally. As a result, the condition of bridges in Shanghai has deteriorated rapidly.

Fatigue Behavior Assessment Method of the Orthotropic Steel Deck for a Self-anchored Suspension Railway Bridge

A self-anchored suspension bridge with a large span arrangement (210+600+200) m is designed for urban railway in the city Chongjin of China. The deck system of the bridge also has some special features. A rubber layer between the concrete slabs and the orthotropic steel deck is used to absorb the vibration energy. In order to study the fatigue behaviour of the orthotropic steel deck, a finite element model is established, and the weld in the rib-to-diaphragm region is modelled by the oblique shell element. After the reference stress was defined, the stress influence lines of the details were calculated, and then the stress ranges were counted by the rain-flow method. The nominal stress method was adopted to assess the fatigue behaviour of the concerned part. Apart from that, the circle form cut out was compared with the key form used in this bridge. Due to the stress dispersing in the concrete slab, the results show that the stress ranges keep at a relatively low level in the details of the two cut out forms. The key form of a cut out is eventually adopted because it is easy to assemble the ribs and diaphragms with a relatively large weld tolerance.

Phased array ultrasonic nondestructive testing of bead crack in orthotorpic steel deck system

Phased array ultrasonic nondestructive testing of bead crack in orthotorpic steel deck system

한옥의 경사처마와 이중바닥구조에 관한 연구

본 논문은 공동주택에 적용 가능한 한옥구조 평면기술에 관한 연구로서, 한옥의 특징들을 구조적, 기능적 측면으로 분석하여 이를 공동주택 평면에 적용하는 방안을 제안하였다. 기존 지붕처마 각도를 중심으로 하지, 동지의 남중고도를 반영한 실내 일사깊이를 계산하여 효율적인 슬래브 경사 및 층고를 갖는 경사발코니 구조를 제안하였다. 이는 해당 슬래브 하부층에 적용되는 것으로 기존의 단층적인 한옥의 한계를 극복하여 모든 층의 동일한 일사량 및 전망권을 제공할 수 있으며 한옥의 정원개념을 수직공동주택에 적용가능하게 해준다. 전통 한옥의 처마 내밀기와 귀솟음을 응용한 경사발코니의 각도는 30o도 내외가 적당하고, 층고는 <TEX>$4.5{\pm}0.25m$</TEX>가 경제적인 것으로 분석되었다. 또한 기존 한옥의 뜬 바닥 구조를 분석하여 소음, 진동, 온도 전달에 관련된 원리들을 공동 주택 평면에 적용 가능하도록 개선안을 모색하였으며 기존 공동주택과 달리 복층바닥구조는 단일슬래브에 비하여 바닥충격음 66%정도 저감되는 것으로 나타났다. 이중바닥구조는 주택 평면에서 사라지고 있는 수직적 공간(다락 및 하부저장공간)을 제공함으로써 효율적인 내.외부 공간관리가 가능한 것으로 나타났다. The purpose of this study is to propose and analyse new technology of structural elements design for Korean-style house(Hanok). Design of modern apartment building adopts many aesthetic elements from Hanok, however, these are only for the decorations of interior. In this study, projected Hanok eaves were studied in terms of the length of solar insolation. Inclined front slab system has been proposed utilizing sloping roof to an apartment building section. This system can provide the same sunshine radiation length and outside view to all levels of building to overcome the limitation of traditional hanok. It also can be applied to all residences the vertical garden concept of hanok. Inclined slab system showed 20% more efficient than flat slab system in terms of solar insolation length. This study also suggested a double deck slab system for not only reducing apartment floor impact noise but also connecting concept of traditional maru system in hanok. Double deck system reduces 66% of floor impact noise comparing with single deck slab of modern apartment buildings.

Fatigue Life Prediction of Heavy-Duty Riveted Steel Gratings in Bridge Decks

AbstractHeavy-duty riveted steel gratings often occur as open-grid deck systems used in movable bridge construction and in rehabilitation projects due to their light weight compared with conventional systems. Open-grid decks have been used in a number of bridges, with the majority fabricated as welded decks. Field and laboratory experience with heavy-duty riveted steel gratings indicates improved fatigue performance compared with welded decks, but no specific provisions currently exist. This study explored a fatigue life prediction methodology for riveted gratings using fracture mechanics. The models involve crack growth rate relations and approximate stress intensity factor solutions for a crack in a bearing bar of the grating. Two failure modes of the riveted gratings were considered based on results of fatigue testing of both full-size and smaller-size samples of a 37R5 lite panel under various stress ranges. Results from the fracture mechanics approach compared well with experimental results. The prop...

System transverse in-plane shear stiffness of pultruded GFRP bridge decks

The static transverse behavior of two pultruded GFRP deck systems with trapezoidal (DS) and triangular (AS) cell cross-sectional geometry was experimentally investigated in order to study their transverse in-plane shear stiffness. Symmetric three-point bending experiments up to failure were performed on 200-mm-wide beams. Their stiffness, strength and failure modes were compared. Different load transfer mechanisms were found in the DS (frame-dominated) and AS (truss-governed) systems depending on the cell geometry. The DS beams exhibited a lower apparent bending stiffness (24–30 times less) and degree of composite action between the flanges (14–17 times less) than the AS beams. These dissimilarities were attributed to the lower transverse in-plane shear stiffness provided by the trapezoidal core than by the triangular core. The low bound values for both system in-plane shear moduli were estimated from the experimental deflection results. The system in-plane shear modulus of the DS beams represented approximately 2–3% of that of the AS beams.

Novel UHPC-CFRP Waffle Deck Panel System for Accelerated Bridge Construction

AbstractA novel deck system is developed as an ultralightweight low profile waffle slab of ultrahigh-performance concrete (UHPC) reinforced with carbon-fiber-reinforced polymer (CFRP) bars. The proposed system lends itself to accelerated bridge construction, and has great potential for deck replacement in bridges with load restrictions, and as well for bridge widening. A total of seven specimens at two different overall depths, with single or multiple ribs and in simple or two-span configuration, were tested in two consecutive phases in this study. The results were compared to similar deck panels with high-strength steel (HSS) reinforcement from previous studies. The study confirmed that the proposed deck panel with only 102 mm overall depth and a self-weight of 0.9 kN/m2 meets the demand for a 1,219-mm stringer spacing. The flexural behavior and failure modes of the deck are in general similar to the UHPC-HSS deck. The deck is not susceptible to punching shear of its thin slab and fails in a ductile man...

The optimum overlay thickness of prefabricated full-depth precast concrete bridge deck panel system – 3D non-linear finite element modeling

Segmental construction of prefabricated full-depth concrete bridge deck systems results in numerous transverse and longitudinal joints as well as shear connector pockets that receive cast-in-place concrete or grout. In such systems, it is necessary to overlay the bridge deck to provide smooth riding surface and to protect the underlying deck reinforcement from the deicing salts-induced corrosion and consequent spalling and delamination of the concrete.This paper reports on results and findings obtained from a non-linear finite element analysis (NLFEA) of a prototype prefabricated full-depth precast concrete bridge deck panel system before and after being overlaid with various plain and fibrous latex-modified concrete (LMC) and microsilica concrete (MSC) overlays. The NLFEA were validated with experimental results obtained from full-scale testing of the prototype bridge system. The benefits of the NLFEA can be highly appreciated when visualizing the substantial time and cost savings, the ability to change any parameter of interest, and the capability of demonstrating any interesting response at any load value and at any location in the system. The most attractive results were: (1) adequately bonded LMC or MSC overlay significantly improves the stiffness, cracking load, and ultimate strength capacity of the system, (2) AASHTO HS20 truck induced bond stresses were below the bond strength of bonded LMC and MSC overlays, (3) the fibrous overlay has desirable crack arresting characteristic.

A genetic algorithm-based multi-objective optimization for hybrid fiber reinforced polymeric deck and cable system of cable-stayed bridges

As the length of main span of cable-stayed bridge increases, several technical challenges become more prevalent with traditional materials. Such technical challenges include: large axial stresses i...

영구거푸집으로 활용한 FRP 판의 종류에 따른 콘크리트와의 부착응력에 관한 실험적 연구

Development of new concrete bridge deck system with FRP plank using as a permanent formwork and the main tensile reinforcement recently has been actively conducted. Concurrent use as a reinforcing material and a permanent formwork, it is possible to reduce the construction time and construction costs than the usual concrete slab. In this study, an experiment was carried out for the bond stress between cast-in-place concrete and the type of FRP plank using as a permanent formwork. The interfacial fracture energy that can be one of the most important parameters were evaluated for adhesion performance and bond stress to know the characteristics of the failure mechanism of the adhesion surface. Interfacial fracture energy of normal concrete is 0.24kN/m of GF11 case, in the case of GF21, 0.43kN/m appears, in the case of CF11 and GF31, 0.44kN/m and 0.46kN/m respectively it appeared. In case of RFCON, 0.52kN/m appears from GF12, the CF12 and GF22, 0.51kN/m and 0.36kN/m appeared each case.

Analysis of Shrinkage and Creep Effects on New Steel-Concrete Composite Deck System for Suspension Bridge

AbstractTo study the shrinkage and creep of the new steel-concrete composite deck system of a suspension bridge, an equivalent calculation method based on the existing calculation theory of shrinkage and creep with changing temperatures and creep guidelines was proposed. Two different validation analysis models were established for the same structure using two largely popular finite element programs. The validity and accuracy of the equivalent results were verified, and the equivalent method was found to be practical, feasible, and highly accurate. A fine segment model for the steel-concrete composite bridge deck system of a suspension bridge was created with the use of the ANSYS finite element program. Further research was conducted on the effect of shrinkage and creep on a composite structure using the proposed equivalent calculation method. Research results for the new class of steel-concrete composite bridge deck indicate that the concrete shrinkage effect is dominant, but the creep effect is relative...

Slim‐floor construction using hollow‐core and composite decking systems

AbstractThis article reviews the performance characteristics of and some recent developments in slim‐floor and integrated beam construction. This form of construction provides a flat floor using precast concrete slabs or deep composite decking and offers advantages over other forms of construction in many sectors. Composite slim‐floor beams have superior stiffness and can achieve longer spans.

Fatigue behavior of hybrid GFRP-concrete bridge decks under sagging moment

This paper presents a new cost-effective hybrid GFRP-Concrete deck system that the GFRP panel serves as both tensile reinforcement and stay-in-place form. In order to understand the fatigue behavior of such hybrid deck, fatigue test on a full-scale specimen under sagging moment was conducted, and a series of static tests were also carried out after certain repeated loading cycles. The fatigue test results indicated that such hybrid deck has a good fatigue performance even after 3.1 million repeated loading cycles. A three-dimensional finite element model of the hybrid deck was established based on experimental work. The results from finite element analyses are in good agreement with those from the tests. In addition, flexural fatigue analysis considering the reduction in flexural stiffness and modulus under cyclic loading was carried out. The predicted flexural strength agreed well with the analytical strength from finite element simulation, and the calculated fatigue failure cycle was consistent with the result based on related S-N curve and finite element analyses. However, the flexural fatigue analytical results tended to be conservative compared to the tested results in safety side. The presented overall investigation may provide reference for the design and construction of such hybrid deck system.

Effect of shear stud clusters in composite girder bridge design

As part of ongoing efforts to accelerate bridge construction in Ontario, the Ministry of Transportation of Ontario (MTO) has turned increasingly to prefabricated bridge technology as a bridge construction method when conditions allow. One of the prefabricated deck systems commonly used by MTO involves installing precast full-depth deck panels with pre-formed shear pockets on top of the naked steel girders, which are then made composite with the girders through shear studs installed inside the shear pockets. Construction of the deck slab is completed by filling the shear pockets with in situ concrete. Recent prefabricated bridge projects have shown an increasing tendency to concentrate the shear studs into clusters of closely-spaced studs in shear pockets that are spaced at relatively large distances apart. Concerns have been raised about the effectiveness of the resulting composite action between the precast panels and the supporting girders. As a result, MTO’s Bridge Office recently carried out a comprehensive experimental research study to investigate the issue by using reduced scale models of single composite beam systems as well as shear push-out specimens. This paper describes the laboratory research project and the tests that were carried out and discusses the results obtained. Comparisons with theoretical results are made to assess the composite action that is developed. Experimental test results indicate that closely-spaced studs in the shear pockets in the precast deck panels provide adequate composite action in composite bridge girder design.

A statistical framework with stiffness proportional damage sensitive features for structural health monitoring

A modal parameter based damage sensitive feature (DSF) is defined to mimic the relative change in any diagonal element of the stiffness matrix of a model of a structure. The damage assessment is performed in a statistical pattern recognition framework using empirical complementary cumulative distribution functions (ECCDFs) of the DSFs extracted from measured operational vibration response data. Methods are discussed to perform probabilistic structural health assessment with respect to the following questions: (a) "Is there a change in the current state of the structure compared to the baseline state?", (b) "Does the change indicate a localized stiffness reduction or increase?", with the latter representing a situation of retrofitting operations, and (c) "What is the severity of the change in a probabilistic sense?". To identify a range of normal structural variations due to environmental and operational conditions, lower and upper bound ECCDFs are used to define the baseline structural state. Such an approach attempts to decouple "non-damage" related variations from damage induced changes, and account for the unknown environmental/operational conditions of the current state. The damage assessment procedure is discussed using numerical simulations of ambient vibration testing of a bridge deck system, as well as shake table experimental data from a 4-story steel frame.

Retrofit of an orthotropic steel deck with compact reinforced reactive powder concrete

Compact reinforced reactive powder concrete (CRRPC) was proposed to retrofit deteriorated asphalt overlays and to strengthen orthotropic steel deck (OSD) bridges. The resultant OSD-CRRPC composite deck is also referred to as a light-weight composite deck (LWCD) system. This paper provides experiences and lessons learned from the first application of CRRPC to retrofit the deficient asphalt overlay of an existing steel bridge in China. The paper includes information relating to finite element (FE) model analyses, a fatigue loading test, construction processes and a field measurement. FE analyses revealed that a 50-mm CRRPC layer decreased the vehicle-induced stresses in the OSD by 34–83% relative to an OSD with an 80-mm asphalt overlay. As a result, the fatigue life of the OSD could be extended significantly. The static and fatigue safeties of CRRPC were proved by comparing the predicted and experimental stresses, and field construction demonstrated the feasibility of the proposed system. CRRPC developed no shrinkage cracks after hot-steam treatment in field application. In addition, a field measurement verified that CRRPC outperformed an asphalt overlay in reducing the vehicle-induced stresses in the OSD. The results demonstrate the safety and feasibility of retrofitting and strengthening OSD bridges with CRRPC.

Structural monitoring and 8-year load test on Europe's first fibre-reinforced polymer highway bridge

In October 2002 the first all-fibre-reinforced polymer (FRP) composite bridge on the public highway network in Europe, West Mill Bridge, UK, was installed. The design and construction of this bridge was the culmination of a 4-year EU research project called Asset, to develop a heavy-duty FRP bridge decking system for use in repairing, upgrading and new civil infrastructure. As part of this project, a monitoring system was installed on the bridge during fabrication. In addition to an initial controlled load test on installation of the bridge, further controlled load tests using a 30 t lorry have been undertaken after 3 years and 8 years. The results from these load tests confirmed the medium-term structural behaviour to be essentially unchanged from the original structural behaviour. In particular, a high level of composite action between the glass fibre reinforced polymer deck, FRP main beams, and concrete parapet beams was still present after 8 years of service.

Parametric Study on Dynamic Response of Fiber Reinforced Polymer Composite Bridges

Because of high strength and stiffness to low self-weight ratio and ease of field installation, fiber reinforced polymer (FRP) composite materials are gaining popularity as the materials of choice to replace deteriorated concrete bridge decks. FRP bridge deck systems with lower damping compared to conventional bridge decks can lead to higher amplitudes of vibration causing dynamically active bridge deck leading serviceability problems. The FRP bridge models with different bridge configurations and loading patterns were simulated using finite element method. The dynamic response results under varying FRP deck system parameters were discussed and compared with standard specifications of bridge deck designs under dynamic loads. In addition, the dynamic load allowance equation as a function of natural frequency, span length, and vehicle speed was proposed in this study. The proposed dynamic load allowance related to the first flexural frequency was presented herein. The upper and lower bounds’ limits were established to provide design guidance in selecting suitable dynamic load allowance for FRP bridge systems.

Aerodynamic Essentials for Crew Station Design Teams

Increasing emphasis is being placed on various aspects of flight dynamics in aviation. This includes such things as upset and stall recovery, wind shear recovery, and approach instability recovery. Operators, safety analysts, and designers are now actively discussing “dynamic situation awareness.” Because of this, there is the need to understand the dynamic nature of flight operations, and incorporate this understanding in state-of-the-art flight deck systems and training programs. This article offers designers, operators, and trainers a quick review of some of the most important aspects of flight dynamics so as to develop programs, procedures, and systems that contribute directly to improving dynamic situation awareness.