Precast Piers Research Articles

Full-scale test of the hydration heat and the curing method of the wet joints of a precast segmental pier of a bridge

Although prefabricated segmental structures, especially for use as a sea-crossing bridge, exhibit high quality and are barely affected by the environment and climate, more attention should be paid to the wet joints to ensure the durability of such structures (e.g. a precast segmental pier). Using one offshore bridge as a reference, this study reports the results of full-scale model tests performed to determine the factors of the hydration heat, with focus on two types of concretes integrated using different curing methods. The wet joint concrete admixed using an expansive admixture and a painting compound curing method proved to be satisfactory and thus recommended for use on the reference bridge. Inspections for over five years of the reference bridge proved that the results were better than expected.

Performance assessment of precast concrete pier cap system

The purpose of this study was to investigate the performance of precast concrete pier cap system. The proposed precast pier cap provides an alternative to current cast-in-place systems, particularly for projects in which a reduced construction time is desired. Five large-scale pier cap specimens were constructed and tested under quasistatic monotonic loading. The computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used for the analysis of reinforced concrete structures. A bonded tendon element is used based on the finite element method, and can represent the interaction between the tendon and concrete of a prestressed concrete member. A joint element is used in order to predict the inelastic behaviors of segmental joints with a shear key. This study documents the testing of the precast concrete pier cap system under monotonic loading and presents conclusions and design recommendations based on the experimental and analytical findings. Additional full-scale experimental research is needed to refine and confirm design details, especially for actual detailing employed in the field.

Seismic Analysis of Precast Segmental Bridge Piers of the Hunter Expressway Viaducts and the Proposed Amendment to Bridge Code AS5100.2

The method of deriving the seismic design force in the current Australian bridge design code AS5100.2–2004 is force based and requires the use of a structural response factorRf which is not defined for a structural system consisting of precast segmental concrete piers. There is an initiative to amend the current bridge design code to make it compatible with the changes made in AS1170.4–2007. The initiative also includes displacement based design method as an alternative to the current force based design method. This approach is new in the Australian design offices and there is a need to assess the impact these amendments will create. This paper details the workings of a performance based analysis to derive the seismic horizontal design force for the precast segmental concrete piers which meets the design requirements of the current bridge design code without usingRf. The effect of changes in AS1170.4–2007 and the outcome of implementing displacement based design method in the design of the precast pier have been discussed. The design feature of the Hunter Expressway viaducts which was developed to meet the requirements of AS5100.2–2004 is used to compare the effect of such proposed changes.

Experimental study of telescopic steel bar connection technology in precast pier

Experimental study of telescopic steel bar connection technology in precast pier

긴장재를 사용하지 않은 프리캐스트 교각의 내진성능 실험 연구

본 논문은 PC 텐던 등에 의한 긴장력을 도입하지 않고 일반 철근만을 사용한 프리캐스트 교각의 내진성능을 검증하기 위하여 프리캐스트 교각의 실물모형 내진성능 실험을 실시하였다. 프리캐스트 블록은 축방향 철근 3개를 하나의 홀로 삽입되도록 하여 시공성을 향상시켰다. 프리캐스트 유무와 FRP보강 유무를 실험변수로 하여, 동일한 형상의 3개의 실험체에 대하여 실험을 실시하였고, 파괴형상, 반복 횡하중에 대한 연성능력을 평가하고 각 시험체의 강성저하에 따른 감쇠비, 강성 저감과 소산에너지 등을 비교하였다. 실험결과, 프리캐스트 교각의 시공성과 내진성 및 FRP 보강에 의한 내진성능 향상을 확인할 수 있었다. In this study, the tests of seismic performance for full-scale models of the precast pier were conducted in order to verify the seismic performance of the precast pier using general rebar without introducing prestressing force such as a PC tendon. The constructability of the precast blocks was improved by inserting three rebars on an axis direction into a one hole. The tests for three piers with identical form were carried out, with use of precast and FRP reinforcement as test variables. The ductility for failed shape and cyclic transverse loads was evaluated. The damping ratio, stiffness reduction, and energy dissipation according to reducing stiffness were compared. These tests proved improvement of constructability and seismic performance for precast pier and of seismic performance for FRP reinforcement in their results.

Seismic Performance Analysis of a Continuous Girder Bridge with Precast Segmental Pier

Based on available research results of precast segmental bridge pier, seismic performance of a continuous girder bridge with precast segmental bridge columns using match-cast dry joints was analyzed with the lumped plastic hinge method verified by experiment, the similarities and differences of seismic performance between the continuous girder bridge with precast segmental bridge columns and that of cast-in-placement reinforced concrete bridge columns were gained. Results show that the maximum displacement response of the continuous girder bridge with precast segmental bridge columns is bigger than that of the continuous girder bridge with cast-in-place reinforced concrete bridge columns. While for the residual displacement, the opposite is true. The reason is that the restoring force exists in the precast segmental bridge pier by the prestress strands. The concentrated plastic hinge method for cast-in-place reinforced concrete bridges could be used to bridges with precast segmental bridge columns.

Experimental evaluation of seismic performance of precast segmental bridge piers with a circular solid section

Rapid bridge construction is in high demand in the construction industry, due to strict requirements on work-zone safety and traffic control during construction. Prefabricated bridge piers have been proposed for the fast construction of bridge substructures. This study deals with quasi-static tests on precast piers with bonded prestressing bars and steel tubes. One of the most crucial aspects in the design of precast prestressed concrete bridge piers is the seismic performance. Seven precast pier specimens with single-segment and two-segment systems were fabricated. The main test parameters were the number of prestressing bars, the prestressing force, and the location and number of joints between the segments. Test results showed that the introduced axial prestress allowed the restoration of the deformation under small lateral displacements, resulting in minor damage. However, there was no effect of the prestress on the self-centering capability when the plastic hinge region was damaged severely due to a large lateral displacement. Judging from the observed damage, the design of the joints in precast piers should focus on the first joint between the foundation and the pier segment, for crack control. In order to satisfy the current required displacement ductility, it is necessary to have the same amount of transverse reinforcements as in reinforced concrete piers. As the steel ratio increases, the plastic deformation and its energy absorption capacity increase after reaching its maximum strength. The number of joints showed some influence on the energy absorption capacity.

중실원형단면 조립식 교각의 내진 성능 평가

건설여건의 변화에 따라 교량구조물의 급속시공에 대한 요구가 늘어나고 있다. 이 논문에서는 하부구조에서 교각의 프리캐스트화를 위한 준정적 실험을 수행하였다. 프리캐스트 프리스트레스트 콘크리트 교각 설계의 가장 주요한 항목이 내진성능의 확보에 있다. 7개의 프리캐스트 교각을 제작하였고 주요 실험변수는 긴장재의 양, 프리스트레스트의 크기, 이음부의 위치 및 수로 설정하였다. 실험결과 축방향으로 도입되는 프리스트레스에 의해 작은 횡변위하에서는 일부 손상이 발생하여도 변형의 복원력을 발휘하였지만 소성힌 지구간의 손상이 많은 경우에는 이러한 복원력이 효과를 발휘하지 못하는 것을 확인하였다. 실험을 통해 관찰된 손상의 형태로부터 판단할 때 조립식 교각의 이음부 설계는 기초부와 교각부 사이의 이음부에 대해서 실시되어야한다. 축방향 긴장재의 양은 RC 교각과 강재비를 일치시키는 것은 지나친 설계가 될 수 있고 주어진 하중조건에 대한 P-M 상관도를 만족시키는 수준에서 결정되어야 한다. 변위연성도 평가를 볼 때 프리캐스트 교각에서 횡철근비는 현재의 철근 콘크리트 교각과 동일한 수준에서 확보되어야 요구연성도를 만족할 수 있다. 에너지 소산능력은 강재비가 증가함에 따라 향상되었고 이음부의 수가 많은 경우가 다소 뛰어난 능력을 발휘하였다. Fast bridge construction has been increasingly needed according to the changed construction environment. This paper deals with quasi-static tests on precast piers for bridge substructures. One of the most crucial aspect of the design of precast prestressed concrete bridge piers is the seismic performance. Seven precast pier elements were fabricated. The amount of prestressing bars, the prestressing force, and the location and number of the joint between segments were the main test parameters. Test results showed that the introduced axial prestress made the restoration of the deformation under small lateral displacement and minor damage. However, there was no effect of the prestress when the plastic hinge region was damaged severely due to large lateral displacement. Judging from the observed damage, the design of the joints in precast piers should be done for the first joint between the foundation and the pier segment. The amount of the necessary prestressing steel may be designed to satisfy the P-M diagram according to the service loads, not by having the same steel ratio as normal RC bridge piers. In order to satisfy the current required displacement ductility, it is necessary to have the same amount of the transverse reinforcements as RC piers. As the steel ratio increases, the energy absorption capacity increases. The number of joints showed a little influence on the energy absorption capacity.

New Technologies Proven in Precast Concrete Modular Floating Pier for U.S. Navy

Representing a breakthrough in naval vessel berthing infrastructure, a test bed structure for a large-scale modular hybrid floating pier was designed with state-of-the-art precast/prestressed concrete technology and a number of material and design innovations. In 2004, the $5 million 15.2 x 30.5 x 8.8 m (50 x 100 x 29 ft) test structure was fabricated, erected, and open-ocean towed to its final destination in San Diego, California, as proof of concept for a future $45 million, 400 m (1300 ft) long double-deck floating pier for the U.S. Navy. The Modular Hybrid Pier was conceived as a replacement for obsolete and deteriorating naval berthing facilities. Designed for 100 years of repair-free service, the pier will provide a high level of support services to a variety of vessel classes and facilitate a rapid upgrade of vessel utilities with the advance of fleet support system technologies. More than 25 government, university, and private entities collaborated to develop this groundbreaking concept in precast concrete pier infrastructure.

Innovative Design and Construction of Chesapeake and Delaware Canal Bridge

An outstanding accomplishment of bridge design, construction, and management, the Chesapeake and Delaware (C&D) Canal Bridge demonstrates that precast, segmental, cable-stayed bridges can be an economical and aesthetically pleasing solution in an area of the country where steel bridges are predominant. The C&D Canal Bridge is the first major concrete segmental cable-stayed bridge structure to be completed in the Northeast. The $58 million C&D Canal Bridge is a precast concrete, segmental structure 1417 m (4,650 ft) in length. Twin parallel box girders were designed to provide six lanes of travel with a total bridge width of 38.7 m (127 ft), with each precast box girder containing three 3.65-m (12-ft) lanes and two 3-m (10-ft) shoulders. Innovative construction techniques, economy, and aesthetics were the primary focus of the construction and design solutions used for the 229-m (750-ft) cable-stayed main-span crossing. The bridge was completed on schedule, with no claims or suits, at a cost slightly under the original bid. A quality-based selection process for the bridge designer, a prequalification process for the selection of the contractor, a disputes review panel, and informal partnering during construction all contributed greatly to a very successful project. The use of precast concrete elements provided an efficient and time-saving technique for the construction of this bridge. In addition, precast concrete box girders, box piers, and delta frames were designed to anchor the cable stays and make the parallel trapezoidal box girders monolithic throughout the main span.

Physical Modeling of Foundations for Northumberland Strait Crossing

The 13-km-long Northumberland Strait Crossing will become the longest continuous marine span bridge in Canada. The marine and navigational spans of the bridge will be supported by 44 precast concrete piers founded on bedrock using ring-shaped footings in a maximum water depth of 35 to 40 m. Bedrock stratigraphy ranges from massive strong sandstone to a variable sequence of thinly bedded weak mudstones and siltstones. Foundation conditions vary significantly from pier to pier and in several cases can vary through the vertical and lateral extent of a particular foundation. In addition to the complex foundation conditions, the large horizontal environmental loadings on each pier must be considered in the geotechnical analyses. Reduced-scale physical model tests of selected marine piers on a centrifuge investigated potential mechanisms of failure and examined how these mechanisms varied with loading and foundation conditions. The results of the experimental program were used in conjunction with analytical results to enhance the fundamental understanding of the geotechnical aspects of foundation design and have led to an improved design methodology.

SECOND SEVERN CROSSING - VIADUCT SUPERSTRUCTURE AND PIERS.

This paper describes the design and construction of the 4.2 km long viaduct for the second Severn motorway bridge between England and Wales. The design of the precast segmental deck was heavily influenced by the Government's requirement of external post-tensioning tendons with free lengths limited to 40% of span. Over 2200 deck units up to 200 t in weight were match-cast on site and erected in balanced cantilever using a 234 m long launching gantry. The paper also describes the precast concrete piers, elastomeric bearings, movement joints, deck finishes and furniture, mechanical and electrical works (including a monorail deck access train and three service gantries) and the toll plaza. (A) For the covering abstract see IRRD 896358.

SEGMENTAL BRIDGE CONSTRUCTION IN FLORIDA; A REVIEW AND PERSPECTIVE.

This Paper offers an overview of the precast concrete segmental bridges designed and built in the state of Florida, during the past ten years. Statistical structural parameters, segment manufacturing and erection methods, construction times, costs and problems typically encountered are summarized. Current industry and nationwide design and construction practices are discussed with some suggestions for possible improvements. Over the past ten years, Florida has been a leading State in the design and construction of present segmental bridges. Applications include complex interchange locations and long spans, usually in excess of traditional precast girder construction. With the exception of the main span portion of the New Sunshine Skyway cable stayed bridge, they fall into two groups: either straight span-by-span over water or curved balanced cantilever viaducts at complex interchanges where this technique readily accommodates the varying alignments, spans and maintenance of traffic requirements typical of such locations. Variations in superstructures, substructures and foundation types reflect both project requirements and the philosophies of different designers. In general, span-by-span as opposed to cantilever construction afforded more standardization of precast superstructures, pier shafts and foundations which led to very efficient erection systems. In cantilever construction, spans, segments, piers and foundations varied more according to the application. Most contractors preferred to establish their own yards for present segment production, according to the project size and duration, writing off the costs on each, although some reuse of facilities and equipment was possible. Well made equipment, particularly casting forms, saved time and money despite higher initial outlay. Segment production typically attained a rate of one segment per day per casting cell after an initial mobilization and learning period. In conclusion, segmental bridges have proved to be very successful in Florida. Occasional difficulties afforded opportunities for learning and improvements, not only in segmental bridges, but also in many other areas. The proven record and benefits of segmental technology offer considerable scope for the future. (A)

PROPOSED TRANS-ALASKA INTEGRATED PIPELINE TRANSPORTATION SYSTEM

The proposed scheme to build an Integrated Pipeline Transportation (IPT) system across Alaska is not only technically feasible but would also bring farreaching economic benefits to North America. The IPT plan, proposed by Prof. T. Y. Lin, would incorporate oil and gas pipelines, rapid transit, communications, and utilities in one 800-mile long giant three-tiered concrete tube elevated 30 or more ft above the Alaskan permafrost. The scheme would provide a sensible solution to the current trans-Alaska oil pipeline controversy. If constructed, this $6 billion dollar project would be made of 20 million cu yds of concrete and 1 million tons of reinforcing and prestressing steel. The IPT structure would consist of precast piers and precast concrete segments tied together with post-tensioning. The erection would be accomplished using bridge launching trusses. This article describes the proposed IPT system (including its structural design features) and how it could be constructed, gives the advantages and obstacles to the plan, a breakdown of the cost, and discusses how the project could be financed.