Finding the optimum layout for cable-stayed bridge in conceptual design

<p>In the cable-stayed bridges the primary cost components of the load-bearing material, in the longitudinal direction of the bridge, are the cables. The longer the bridge, the higher the share of the costs of the load-bearing material. The quantity of the cables and the cost optimized cable and tower topology can be reliably solved, already in very early design stages, using a simple calculation method proposed in this article. The cables are considered as a curtain structure and the cable forces are calculated for the permanent load balance. The solutions are performed mathematically by using integral calculus based on a force length method and a unit bridge concept. The results provide a good idea of the optimum pylon height for both one-pylon and two-pylon bridges. The optimum pylon height depends on the span ratio and the chosen cable system.</p>

Rose Fitzgerald Kennedy bridge over the River Barrow. Design and Construction of a long span extrados bridge

<p>This paper describes the key elements from early planning to completion of a new bridge over the River Barrow which is part of the New Ross bypass in the south of Ireland. The structure has a total length of 887m, with a span arrangement of 36-45-95-230-230-95-70-50-36m. The two central twin spans are the longest of its kind in the world (extrados with a full concrete deck). The bridge carries a dual carriageway with a cable arrangement consisting of a single plane of cables located in the central axis of the deck. The design and construction focused in providing a structure with long term durability, resilience, and a robust approach to design scenarios using the Eurocodes and state of the art analysis techniques, including extreme events such as fire and ship impact<i>.</i></p>

Machine learning-based failure mode identification of RCSPSW

<p>Reinforced concrete – steel plate composite shear walls (RCSPSW) have attracted great interests in the construction of tall buildings. From the perspective of life-cycle maintenance, the failure mode recognition is critical in determining the post-earthquake recovery strategies. This paper presents a comprehensive study on a wide range of existing experimental tests and develops a unique library of 17 parameters that affects RCSPSW’s failure modes. A total of 127 specimens are compiled and three types of failure modes are considered: flexure, shear and flexure-shear failure modes. Various machine learning (ML) techniques such as decision trees, random forests (RF), <i>K</i>-nearest neighbours and artificial neural network (ANN) are adopted to identify the failure mode of RCSPSW. RF and ANN algorithm show superior performance as compared to other ML approaches. In Particular, ANN model with one hidden layer and 10 neurons is sufficient for failure mode recognition of RCSPSW.</p>

Experimental study on seismic performance of suspended ceiling components

<p>Suspended ceiling systems (SCSs) experienced severe damage during strong earthquakes that occurred in recent years. The capacity of the ceiling component is a crucial factor affecting the seismic performance of SCS. Therefore, a series of static tests on suspended ceiling components under monotonic and cyclic loadings were carried out to investigate the seismic performance of the ceiling components. The ceiling components include main tee splices, cross tee latches and peripheral attachments. All specimens were tested under axial loading. Additionally, the static tests of cross tee latches subjected to shear and bending loadings were performed due to their seismic vulnerability. The failure pattern, load-carrying ability, deformation capacity and energy dissipation of the ceiling components are presented in detail in this study.</p>

Site controlling in infrastructure projects by digital methods

<p>The construction industry is essentially determined by digital transformation and an increasingly complex market environment. Project controlling and monitoring is of high importance for construction site activities to achieve the project goals. Digital planning and recording methods make it possible to identify deviations at an early stage and to ensure the profitability of the project. To discuss the current practice of construction performance measurement as well as digital approaches in this domain, a qualitative study was carried out. The results of this empirical analysis examine the status quo of the construction performance measurement in civil engineering companies to illustrate the currently used methods and trends. Findings for the future use of digital planning and recording methods were obtained from the investigation. Based on empirical hypotheses, recommendations for action as well as for an improved process model are given.</p>

Shear connection between precast concrete bridge segments built with thin-walled elements

<p>Segmental bridge construction combines the advantages of prefabrication, for example the reduction of construction time and very high product quality, with those of common bridge erecting methods. Short precast segments are assembled and prestressed to form the complete superstructure. New methods divide these segments into prefabricated elements to create new lighter versions of the segments. For this to work, new joint types must be developed which can ensure the force transfer between the segments. In this paper, several methods, including a new concept for joining thin-walled pre-fabricated elements, are described. Push-off tests with a constant lateral force were carried out to assess the shear strength and deformation behaviour. The main parameters were the joint type (wet joints: plain, grooved, keyed; dry joints), the mortar type, and the level of lateral force. In this paper, the test results are presented and recalculations with a design code are shown.</p>

Enhancing the application potential of dissipative controlled rocking connections through detailing and design

<p>Research on low-damage systems has been significant in the past decade. These systems combine post- tensioning, which provides self-centring; and typically use replaceable devices, which give energy dissipation. WSP has used recent research, carried out at the University of Canterbury, on low-damage bridge piers and applied this into a real structure – the Wigram-Magdala Link Bridge. This is believed to be the first bridge in New Zealand and possibly worldwide to adopt such a system. Given this was the first application of the system to a real structure, there were some valuable learnings during design and construction. Firstly, the application of axial dissipaters has some limitations due to available material sizes, construction difficulty and aesthetics. Secondly, there is still some additional cost and complexity associated with using the low-damage system. Given these difficulties, this paper presents an alternative design philosophy which better captures the benefits of the low-damage system, which include cost-effective repair method, controlled damage and additional robustness and resilience. The alternative design philosophy presented is expected to result in reduced construction costs by reducing pier and foundation demands. Peak displacements and forces will be compared to the results from non-linear time history analysis to verify the performance of the low-damage connection using scaled ground motions. Furthermore, the paper will present the possible application of an alternative dissipation device, the lead extrusion damper, which can further improve the performance of low-damage connections.</p>

Two important bridges protected from earthquake by extremely big sliding pendulum isolators

<p>The Padma Bridge is a multipurpose road-rail bridge across the Padma River currently under construction in Bangladesh and is one of the most important projects in the whole south east Asia with a total length of 6150 m. The maximum design vertical load reaches 98725 kN.</p><p>The Holtekamp Bridge is a steel road bridge with 2 main spans of 150 m and 2 lateral spans of 75 for a total length of 450 m. The bridge is isolated by use of sliding pendulum isolators having a maximum vertical load capacity at ULS of 54915 kN.</p><p>In both cases the isolators are double sliding surface type but with a different approach about the central articulation. The paper aims to put in evidence the difference in behaviour of the 2 types of pendulum, analysing both the theoretical approach and the test results with a special focus over the adopted solution for perform the test on a device which exceed the capacity of aby existing laboratory.</p>

Quality assurance and quality control to ensure durability

<p>High level of quality during design, design-build and construction stages is a fundamental requirement to ensure that structure serves its intended purpose. Establishment of a quality assurance manual is prime necessity. Lack of quality control during design, review and approving design drawings are major reasons for structural failures. Designers and design checkers need to work in tandem to ensure more adequate Quality Assurance &amp; Control (QA/QC).</p><p>In structural design Durability is a key parameter and becomes critical for service life of 100/120 years. In design build and construction stages controlling work quality is important to maintain performance standards. Tailor made quality plan for Design-build Contract is essential. Quality procedures, inspection and testing needs implementation in practice to verify full compliance and prevent occurrence of faults and defects towards durability and service life. This paper deals with Quality with special emphasis on durability in design and construction through case studies of design build contracts.</p>

Extending span ranges and accelerating construction of spread slab beam bridges

<p>A new class of spread slab beam bridges has recently been developed and implemented in Texas. The research questions addressed in this paper are: how long can such a low profile bridge system span in either a simply supported or continuous form? And, can construction operations be accelerated, by design? An effective way to extend the span length is to utilize post-tensioning and to make the bridge continuous over several spans. In order to explore the maximum span limit, the design of a multi-span prestressed concrete spread slab beam bridge is investigated. In addition, a thicker and longer precast prestressed concrete panels (PCPs) that uses concentric pre-tensioned prestress is developed to facilitate accelerated bridge construction by reducing the need for field placement of deck reinforcement. It is shown that the span length may be extended from 15 m to 21 m as a continuous shallow profile bridge. The new solution for PCPs is verified to speed up field operations as compared to the traditional deck with stay-in-place PCPs and cast-in-place toppings.</p>