Erection Procedure Research Articles

Analysis of deployable bridge

The rapid development of infrastructure leads to a wide variety of structural designs, and one of the upcoming techniques is deployable structure. A deployable structure is a structure that can change shape to significantly change size. Deployable structures have many potential applications ranging from emergency shelters and facilities, through relocatable, semi–permanent structures, to space station components. Their main advantages are their small volume during storage and transportation and their fast, easy erection procedure. The motivation behind doing this project is because of its adaptability to the environment and the easiest mode of construction. This project work is done using SOLIDWORKS Software, an application that can be used for structural analysis and designing of the pedestrian deployable bridge. The main aim of this project is to determine the strength of the deployable bridge and to reduce the loss of lives by providing safe transportation that is the designing of deployable evacuation bridge. The problems thus exist so far are that the structure is costly in parts and assembling, and friction in the joints determines the life of the structure.

Bionic artificial penile Tunica albuginea

Bionic artificial penile Tunica albuginea

Structural Dynamic and Buckling Behaviour of Steel Cold‐formed Polygonal Conic Pole for Antennas Support

AbstractSupport for antennas placed as high as 40‐50m demands traditional trussed steel or pole towers, the former with much larger base area than the later and the consequences for the costs of the ground occupancy. This aspect is of upmost importance for both urban and rural areas and the reason for the development of higher steel poles with polygonal cross‐section, searching for slender thin‐walled structures. The present research focus is cold‐formed steel conic twenty‐sided polygon solution allowing 40‐50m high antenna support, for which one must deal with the following challenges: (i) wind‐induced dynamic behavior, (ii) buckling analysis, (iii) localized stress concentration close to the openings along the pole, (iv) connection solution that strongly affects the erection procedure and (v) the fatigue effect. Beyond these aspects, results of the dynamic behavior, elastic buckling, nonlinear structural behavior until the collapse and design procedures for the computation of the structural strength of the steel pole are presented and commented, revealing the importance of structural analysis by combining tailored numerical tools as the finite strip and the finite element methods, as well as frequency domain methods for smooth and turbulent wind actions. Additional CFD and experimental wind tunnel results should be considered for advanced structural design, as well as experimental structural analysis to confirm the set of numerical results and the design procedures adopted for the steel polygonal poles.

Optimization of long-span suspension bridge erection procedure considering flutter risk in mixed extreme wind events

During the erection stage of the suspension bridge, its critical flutter wind speed is continuously varying due to changing structural dynamic properties including mass and stiffness. On the other hand, the wind climate is also varying greatly seasonally or even monthly during the bridge erection procedure. This work proposes an analytical framework to optimize the deck erection timeline under complex wind climate attacks. Xihoumen Bridge built at Chinese southeastern coast is taken as a calculation example. Full-bridge aeroelastic model wind tunnel test was conducted to examine the critical flutter speed at different erection stages. Extreme wind speed for tropical cyclones and synoptic wind are analyzed by tropical cyclone simulation and meteorological records respectively. Results show that the optimal timeline for Xihoumen Bridge is starting in August if a one-month duration is required for each stage. However, if the worst timeline is selected, the flutter risk will be increased 40 times larger. If the construction timeline is flexible for the construction schedule, this research proves that timeline optimization is a more economical and safe approach than structural approaches like storm ropes.

Temporactive pavilion: second design-to-construction loop of an ultra-lightweight temporary architecture

ABSTRACT The paper presents the design to construction process of an ultra-lightweight hybrid temporary structure consisting of a combination of bending-active glass fiber-reinforced polymers arches, a restraining system made of stainless steel cables, and a translucent membrane envelope. After a brief introduction to the basic design concepts and versatility of the modular system to create different shapes, the paper focuses on the fast-track erection procedure that enables to build the pavilion in a very short time. A multi-disciplinary team had collaborated at the design development of the temporary pavilion, built with the aim of deepening a wide range of aspects that are peculiar to temporary architecture. The aim of the second design-to-construction loop, following the first loop which resulted in the construction of the first full-scale prototype, is two-fold: firstly to optimize the innovative mix of lightweight structural components with the aim of reducing the total weight of the building (and thus facilitate transport and installation), and secondly to test the technical details designed to favor reversibility and to ensure the re-usability of the structure for multiple cycles of use. The paper concludes by showing the results achieved and the lesson learned from the first construction of the temporary pavilion in occasion of a one-week event and anticipating the further studies regarding the interface between structure and membrane envelope, also in relation to the building expected life-span and requirements.

Challenges and Safety in Erection and Commissioning of 280/85 Tons Single Failure Proof EOT Crane at PFBR

The Electric overhead traveling (EOT) crane installed in Prototype Fast Breeder Reactor (PFBR), Reactor Containment Building (RCB) is the largest capacity EOT crane installed in any nuclear power plants in India with some unique features of its own. It has been built with a single failure proof concept which is one of the prime requirements of a nuclear facility as per the standards of NUREG/IS. It is a double bridge girder type; the girder used in this crane is a single structure having a length of 34.8m without any joints as designed by IGCAR/BHAVINI (first of its kind). The span of the EOT crane is 33.4m and installed at a height of 42m from the ground level with the lifting height of 42.5m. This crane was manufactured by an Indian company M/s. UNIQUE CRANE, NASIK. Two hooks (280 tons / 85 tons) are connected in the same trolley sharing the Long Travel (LT). Load testing of the complete crane was done at factory before transporting it to PFBR site. The components of the crane were assembled in PFBR site. The erection methodology adopted was distinct w. r. t the site condition, as the components which were handled were very heavy, available space for installation was restricted and the head room was also very less. This erection has been completed successfully and very safely without any notable incidents. This activity is a biggest achievement / milestone in the nuclear industry in India. Later the EOT crane was commissioned, load tested with 350 tons load (negligible deflection) and being operated successfully without any incidents so far. This was achieved by accurate erection procedure, stringent Quality Assurance Plan (QAP), Job Hazard Analysis (JHA) and Safe Operation Procedure (SOP). Many challenges were faced during manufacturing, testing, erection and load testing at site. This paper deliberates those challenges.

Behaviour of RHS beam‐to‐column bolted steel connections

AbstractThe connection concept is a key point in the design of steel structures which affects fabrication, erection procedures and the final costs. Welding processes have been extensively used for tubular trussed girders by combining shop welding with bolted flange solutions to facilitate straightforward connection procedures during erection. The present research addresses the behaviour of innovative beam‐to‐column bolted connections for steel rectangular hollow sections (RHS) which combine simplicity in fabrication and erection, favourable aesthetics for the case of visible structures and structural effectiveness. Four cruciform prototypes were tested under a static non‐reversible bending moment with different bolted conditions: i) non‐friction and ii) friction connection. The experimental results show that the proposed geometry with friction connections is able to develop a rigid elastic moment–rotation response up to usual loading conditions.

Horizontal cladding panels: in-plane seismic performance in precast concrete buildings

The paper investigates the in-plane performance of horizontal precast reinforced concrete cladding panels, typically adopted in one-storey precast industrial and commercial buildings. Starting from in-field observations of cladding panels failures in recent earthquakes, the seismic performance of typical connections is evaluated by means of experimental tests on full-scale panels under quasi-static cyclic loading. The failure mechanisms highlight the vulnerability of such connections to relative displacements and, therefore, the need to accurately evaluate the connections displacement demand and capacity. An analytical model is developed to describe the force–displacement relationship of the considered connections and compared to the experimental results. In order to determine the seismic vulnerability of such connections and provide design recommendations, linear and nonlinear analyses are conducted taking as reference a precast concrete structure resembling an industrial precast building. The results of the analyses show the importance of a correct estimation of the column’s lateral stiffness in the design process and how an improper erection procedure leads to a premature failure of such connections.

Aspectos generales y casos concretos de los trabajos de supervisión estructural del proceso constructivo y medios auxiliares del Puente de la Constitución de 1812 sobre la Bahía de Cádiz

Construction of Constitución de 1812 cable-stayed Bridge over the Cadiz Bay has needed the combination of efforts and determinations of many working teams. Among them, APIA XXI was commissioned by the Ministry of Public Work to develop the Proof Check Consultancy for the more relevant phases of the erection procedure of the bridge. In this article the main tasks carried out inside this field are described. In addition, a specific case of study related to the geometric control of the bridge during the cable staying phases is explained. Finally, an analysis to evaluate the sensitivity to fracture of the retainer bars of the Lifting Frame is presented.

Simple for Dead Load--Continuous for Live Load Steel Bridge Systems

This paper presents the development of design, fabrication, erection and construction procedures for a new steel bridge system referred to as simple for dead and continuous for live loads (SDCL). The economy of the SDCL system depends on several factors, including the use of economical and efficient details over the interior supports. Extensive experimental, numerical and analytical work was conducted to develop economical details and efficient ways of using the SDCL steel bridge system for straight and minimally skewed bridges in which the skew angle is less than 10°. Several bridges were then designed using the research results and their performance from the time of fabrication to construction and their long term behavior were studied. This knowledge was then used to provide detailed information on design, fabrication, erection, and construction procedures for steel bridges using the SDCL system. This paper provides a summary of the entire work, including design recommendations and economical details to be employed in conjunction with the SDCL steel bridge system.

ULTIMATE TROUGH® - Fabrication, Erection and Commissioning of the World's Largest Parabolic Trough Collector

A first Ultimate Trough® (UT) collector demonstration loop was successfully integrated in an existing solar power plant in California and is now put into operation. Its huge dimensions of one Solar Collector Assembly (SCA) with an aperture of 7.5 m and a length of 247 m makes it the largest parabolic trough collector ever built and operated. It is expected that this collector reduces the solar field cost by 20 to 25%.The fabrication and erection of a collector with the present dimensions exceeds present knowledge and experience. To provide safety for the design of upcoming solar thermal power plants with the same collector, it was decided to demonstrate all fabrication and erection procedures as they will be applied in series production.The paper describes the part manufacturing, as well as site assembling procedures, transportation and new developed erection tools. Furthermore, it gives an overview on the assembly process on site.The UT collector is designed to avoid complex and costly SCE alignment procedures in the field. The principles and results of the new SCE alignment method are presented.With this new parabolic trough collector a major step towards solar field cost reduction has been achieved. The development process has reached the final step, and the Ultimate Trough has reached market maturity. It is now planned to be applied for commercial collector field applications.

Erection and Construction HSE MS Procedure

The scope and purpose of this paper lies within the establishment of the causes of accidents in the construction industry. As researches have shown, many workers have died and others left injured when the structures they are constructing collapse or shift. Many of the constructions today are characterized by pressure due to the time limit and financial constraints. The objective of this study is to demonstrate the laid down policies and procedures designed for constructions. This HSE MS Procedure outline the responsibilities associated with the safe erection and the requirements for managing and controlling erection activities at construction sites. This is to ensure clear understanding of safe work practices, encourage safe behavior, and create a constant safe and healthy work environment at all levels.

Calculation of Tension in Cables for Construction of Arch Bridge Using Perturbation Method

Abstract The cantilever construction method with non-framework cable hoisting erection for arch bridge is gaining popularity in recent years. The final stresses and deformations in a finished arch bridge are strongly dependent on the sequence of events during the construction and the erection procedure being used. Therefore, calculation of cable tension is an important step in any analysis of the performance of the bridge at the actual construction sequence. In this paper a method for calculation of tension in cables for construction of arch bridge using perturbation is presented, and it is applied in the construction of Daninghe Bridge to ensure that the arch rib is constructed to line and level. Interestingly, the proposed method is more accurate and shows faster convergence than the common cyclic method.

Analysis of Sliding Cable Element

The sliding cable structures have found its application in many practical structures, such as ski lifts, electrical transmission lines, and cable systems in the erection procedures of long-span bridges. This paper presents a method for modeling the cable sliding on a pulley or sheaves. “Sliding cable element” is developed to solve the general problem. Based on the foundational principles of finite element analysis, the relation of the forces in the element on equilibrium state is used. The computation is simplified by automatically adjusting the cable length on each side of a pulley or sheave in order to maintain equilibrium. The element models are implemented in a geometrically nonlinear, transient implicit finite element program. Several numerical examples are developed to validate the effective of the sliding cable element.

The Maria Pia Bridge: A major work of structural art

This paper presents a technical, historical, and aesthetic study of the Maria Pia Bridge over the Douro River in Porto, Portugal which was designed and built by G. Eiffel and Cie. between 1875 and 1877. Through these analyses, this paper demonstrates the significance of this bridge due to its (1) economy as shown through the design competition, (2) efficiency and safety under self-weight, live, and wind loads as revealed by finite element analyses, and (3) elegance of form which is evaluated through the aesthetic motivation of the designer, international acclaim, and an on-site visual analysis. The primary purpose of the paper is not to suggest that designers today emulate the Maria Pia form, but to shed light on the thought process of the engineers at G. Eiffel and Cie. The conceptual design was imagined through considering the site constraints, the forces acting on the structure, and the erection procedure, ultimately leading to an economical project that won the design competition. This design-build approach can be used more often in 21st century design.

Stonecutters Bridge, Hong Kong: main span erection

To erect a main span of a bridge across the entrance of one of the busiest container ports in the world without causing disruption is a complex operation. Stonecutters Bridge, Hong Kong, was also the second longest cable-stayed span in the world with a unique twin box deck design that was being erected through a typhoon season. Extensive preparation works were carried out from wind tunnel tests in the UK, marine simulations, new erection procedures, typhoon studies and continuous erection analysis. The main span consisted of 53 steel segments weighing between 500 and 600 t and lifted from a purpose-built self-propelled barge. The closure of the main span posed special problems with the large deflection and expansion from a 500 m cantilever, and that the closure segment was in two pieces erected at the same time. The 224 parallel wire strand stay cables were some of the longest and heaviest cables ever erected.

Monitoring system for execution control applied to a steel arch footbridge

The construction of innovative structural systems and the use of unconventional erection procedures need refined tools to assess the phased behaviour and control the site operations. The combination of a specific monitoring system with a detailed numerical model constitutes an adequate tool to assist bridge construction. The application of this tool to the construction of a 275 metre long footbridge, displaying innovative structural characteristics, is discussed in the paper. A dedicated monitoring system, including strain gauges and thermal sensors was implemented to monitor critical cross sections during both the construction process and in-service. A detailed numerical model was developed and applied for the prediction of the phased construction behaviour and to help in the interpretation of the experimental measurements. In this paper the focus is driven to the aspects related with the installation of the monitoring system, the implementation of the bridge model and the discussion of the results obtained during the construction stages, namely the removal of the propping system. The unusual but direct construction procedure used to build the footbridge greatly relied on the monitoring predictions and continuous assessment to control and reduce the inherent risks of the adopted construction process.

Structural Analysis of the Cantilever Construction Process in Cable-Stayed Bridges

This work deals with the analysis of cable-stayed bridges at different erection stages during construction, assuming the full or the partial cantilever method and performing multiple finite element computational procedure. The forward process and the backward process analysis are investigated and compared: the former is performed by following the sequence of erection stages in bridge construction and the latter is carried out in the reverse direction of erection procedures. The required pretension in cable-stays and the corresponding structural configurations of the bridge at different erection stages have been examined and compared in details, also by comparing either the linear computation procedure or the nonlinear computation procedure. Numerical, analytical and construction process results are presented, compared and commented upon.

Numerical Simulation of Cantilever Erection Procedure of Lattice Shell Structures

This paper presented the construction technique of a double-layer spherical lattice shell with a diameter of 66m, while the small-unit cantilever erection method is adopted. The variations of internal forces during the different erection simulation procedures are also indicated. Meanwhile some suggestions are proposed to actual construction.

Research on Resource Optimization of Block Erection Procedure Based on PSO

The resource optimization of ship erection procedure is a classic NP-hard problem. Through analyzing the character about this problem, an algorithm model of Particle Swarm Optimization (PSO) is proposed. Particle’s coordinate in the particle swarm is used for the activity’s actual start time and methods for resource leveling based on dynamic time variance are designed. Evolution equations based on integer compute rule is introduced to improve the converging speed and accuracy of traditional PSO algorithm. The last simulation experiment with the practical data demonstrates the feasibility and the effectiveness of the improved PSO algorithm by comparisons and analyses.