Hurst the purpose of this book is to explain the fundamental principles of design for prestressed concrete structures, and it is intended for both students and practising engineers. Examples of bridges of this type built by the states of tennessee and. Prestressed concrete slab safe load table uniformly distributed superimposed service load in psf. Hollowcore is an extruded, prestressed concrete slab with continuous voids to reduce weight and cost. Molin concrete products company 415 lilac street lino lakes, mn 55014. The prestress losses are defined as the loss of tensile stress in the prestress steel which acts on the concrete component ofthe prestressed concrete section.
The width, depending on the production procedure, is up to 3 m, thickness of the concrete board is 80 120 mm. Lecture 24 prestressed concrete prestressed concrete refers to concrete that has applied stresses induced into the member. Pretensioning and posttensioning in prestressed concrete. Precon designs and builds circular prestressed concrete tanks for water and waste water storage and treatment. Saccoman, chairperson james beerbower ernest markle kevin boyle james markle jeffrey butler milo j. View example in pdf format design example 2 download example as a mathcad. Analysis and design of rcc and posttensioned flat slabs. Oneway slabs normally design as a beam with cables running in the direction of the span at uniform centres. Cpci design manual canadian precast prestressed concrete. The prestressed concrete design of a structure is influenced by either of the two processes, pretensioning, and posttensioning.
Structures design office lrfd design examples files pdfs. Design examples 82 this chapter illustrates the seismic design of precast concrete members using the nehrp recommended provisions referred to herein as the provisions for buildings in several different seismic design categories. Over the past several years there has been a concerted effort to coordinate the requirements in. Design of continuous highway bridges with precast, prestressed concrete girders clifford l.
In pretensioned concrete, the four major sources of prestress losses are elastic shortening. This is particularly so for uncracked prestressed concrete slabs or cracked only in the. Reinforced and prestressed concrete are used extensively in bridge projects. This design example was not intended to follow the design and detailing practices of any. Idea statica is used by engineers for the design of members, crosssections, and details of prestressed and reinforced concrete bridges of small and medium spans. In addition to general design guidance and information on detailing practices, this section contains three design examples. Comprehensive design example for prestressed concrete. Nov 27, 2018 sometimes conventional reinforcement isnt enough.
This design approach can take several forms, including precast columns and. Comprehensive design example for prestressed concrete girder. Prestressed slabs design process submit your plans to ducon conrete ltd and we will calculate, measure, specify and manufacture slabs to suit your project. This introduction of internal stresses is called prestressing and is usually accomplished through the use of tendons that are tensioned or pulled tight prior to being. The quantities of reinforcing steel, prestressing steel, concrete required for the slab, beam and column is calculated for the same and are presented in tabular. The design steps for a two way posttensioned slab was prepared according to the simple. The spreadsheet application presented is ideally suited to making preliminary design decisions quickly and efficiently, leading to better and more cost effective prestressed concrete designs. Deck design follows the nmdot standard deck slab detail in chapter 4 of the nmdot bridge procedures and design guide, hereinafter referred to as design guide.
Solid slab is ideal for short spans with shallow construction depths. The cpci 5 th edition precast concrete design manual is the ultimate publication covering the design, manufacture and installation of precast reinforced and prestressed concrete. Consumption of prestressing steel in the usa cumulative curves. Pretensioned concrete is a variant of prestressed concrete where the tendons are tensioned prior to the concrete being cast 25 the concrete bonds to the tendons as it cures, following which the endanchoring of the tendons is released, and the tendon tension forces are transferred to the concrete as compression by static friction. Pca notes on aci 31805 building code requirements for structural concrete with design applications, eb705. Unbalanced moments and hence curvatures in the regions near the column lines the column strips are greater than in the middle strips. Pdf design of twoway prestressed slabs researchgate. Analysis and design of prestressed concrete flat slab ijirset. Design and typical details of connections for precast and prestressed concrete, second edition. Design and details precon prestressed concrete tanks. Although the emphasis is on design the problem of providing a structure to fulfil a particular purposethis can only be achieved if the designer has a sound. Such a strength outside the range shown in section 4061.
Prepared for the pci hollow core slab producers committee john e. This introduction of internal stresses is called prestressing and is usually accomplished through the use of tendons that are tensioned or pulled tight prior to being anchored to the concrete. It is primarily used as a floor and roof deck system. Typically, wires or tendons are stretched and then blocked at the ends creating compressive stresses throughout the members entire crosssection. In the final version o f the project design basic information of a typical reinforced concrete.
Pretensioning is accomplished by stressing wires or strands, called tendons, to predetermined amount by stretching them between two anchorages prior to placing concrete as shown in fig. Efficient design of prestress concrete bridges demands an accurate prediction of prestress losses. Prestressed concrete is a form of concrete used in construction. Pdf the article is about design of prestressed slabs.
The prestressed floor slabs are used where the loosely reinforced slabs are close to their limits, with regards to load and span width. This lab manual was prepared with the help of the renowned text book design of prestressed concrete structures, 3rd edition by t. Freyermuth design research section portland cement association skokie, illinois continuous highway bridges with precast, prestressed girders have been built by a number of states. Additionally, some recommendations for design to odot will also be made. Comprehensive design example for prestressed concrete psc. When zd is determined, the prestressing force required to balance an. Prestressed concrete is structural concrete in which internal stresses have been introduced to reduce potential tensile stresses in the concrete resulting from loads. Comprehensive design example for prestressed concrete psc girder superstructure bridge with commentary. It comprises of chapters on design of pretensioned and posttensioned flexural members, composite construction of prestressed and in situ concrete, statistically indeterminate structures, prestressed concrete and pipe, prestressed concrete slab and grid floors, and prestressed concrete shell and folded plate structures. Prestressed concrete bridge an overview sciencedirect topics.
Seaa hollow core structural engineers association of arizona, central chapter. A pretensioned prestressed concrete member is cast in a preformed casting. Required concrete strength and moment capacity were computed and compared to those provided. Structural calculations for posttensioned flat slab. Posttensioned concrete design table 11 list of symbols used in the aci 31808 code m bal design moment resistance of a section with tendons and the necessary mild reinforcement to reach the balanced condition, nmm m u factored moment at section, lbin n c tension force in concrete due to unfactored dead load plus live load, lb p. It took until the 1920s and 30s for its materials development to progress to a level where prestressed concrete could be used with confidence. Pti 3 structural material types structural steel prestressed concrete reinforced concrete. The type of reinforced or prestressed concrete bridge deck depends mainly on the functional requirements, the structural form, and the main span length of the construction. The tanks, which are built principally for municipal and industrial users, range in capacity from 50,000 gallons to 20,000,000 gallons and are custom built to the job requirements. Manual for design and detailing of reinforced concrete to the. The integral wearing surface is considered in the weight calculations. Prestressed concrete beam and girder design txdots policy is held firmly to a 6. Beam less floor directly resting on support column and wall is known as flat slab.
Manual for the design of hollow core slabs second edition by donald r. This performance is the result of the practices reported herein, conformance with aci 318. The content is for members only prestressed concrete is basically concrete in which internal. More complicated design typical precast prestressed concrete members. Smaller section sizes since psc uses the whole concrete section, the second moment of area is bigger and so the section is stiffer. Pdf prestessed concrete by n krishna raju book free. Pretensioning and posttensioning in prestressed concrete design pretensioning in prestressed concrete. It comprises of chapters on design of pretensioned and posttensioned flexural members, composite construction of prestressed and in situ concrete, statistically indeterminate structures, prestressed concrete and pipe, prestressed concrete slab and grid floors. Kovacs, in innovative bridge design handbook, 2016.
It was found that a certain amount of poor design was prevalent, and the. For lightweight concrete, the air dry unit weight shall be shown on the plans as 119 lbft. Pci details precast prestressed concrete institute. The precastprestressed concrete institute pci offers a broad spectrum of resources for architects and engineers, including design specifications for both architectural and structural applications.
Smaller deflections the larger second moment of area greatly reduces. This report is intended to serve as a manual of good practice for the design of prestressed concrete flat slabs in addition to the recommended procedures, other methods are described for the sake of completeness and to compare different methods of design. General after making an initial selection of the slab thickness, the second step in slab design is to determine the amount and distribution of prestress. Tensioned bonded strands bonded tendons unbonded tendons internal. It is substantially prestressed during production, in a manner that strengthens it against tensile forces which will exist when in service 35 this compression is produced by the tensioning of highstrength tendons located within or adjacent to the concrete and is done to improve the performance of the concrete in service. Prestressed concrete bridge an overview sciencedirect. Prestressed concrete refers to concrete that has applied stresses induced into the member.
Pretensioning and posttensioning in prestressed concrete design. The rarest solution are monolithic prestressed floor slabs. View example in pdf format design example 2 download example as a mathcad workbook zip adhesive anchor examples. These include pretensioned and posttensioned structures, both castinplace and precast, and other prestressed elements in conjunction with normally reinforced concrete. Design of prestressed concrete girder bridge request pdf.
Bridge piers bridges castinplace into falsework continuous beams with composite slab easy to use specialized wizard reinforcement editor and templates comfortable tendon shape design. Precast and prestressed concrete design is based on the provisions of aci 318 05. Clough a research investigation by abam engineers inc. The design moment of the slab is modified for each design section to include the. An extensive selection of references is given at the end of each chapter. Prestressed concrete is adaptable to a wide variety of structural systems. Chapter 5 covers a design example of a usual precast prestressed structural. Architectural and structural precast prestressed concrete components can be combined to create the entire building. These floors are usually made of prestressed and precast concrete elements. Manual for design and detailing of reinforced concrete to the september 20 code of practice for structural use of concrete 20 2.
View example in pdf format design example 1 download example as a mathcad workbook zip castinplace flat slab bridge design. Prestressed slabs ducon concrete domesticore concrete. Load balancing is used, a portion of the load on slab is balanced by the transverse forces imposed by the draped. There has been an emphasis on tests of prototype and scale model structures in the past, and much current design practice is related to the results of these tests. Lecture 24 page 2 of 12 pretensioned prestressed concrete. Total precast concrete building systems are a popular choice for many construction projects. Prestressed concrete deck panels shall not be permitted for use as stayinplace forms for steel. Hollowcore is very economical and provides great design flexibility. In any span, the max cable sag, zd depends on the concrete cover requirements and the tendon dimensions. Pretensioned concrete is almost always done in a precast plant. Download prestressed concrete by n krishna raju pdf. Design step 4 design of deck prestressed concrete bridge design example task order dtfh6102t63032 43 for this example, a slab thickness of 8 in. Girder analysis and design is performed using the computer. Tensioning building structures march 12, 2020 2020 educode las vegas.
Design of connections for precast prestressed concrete. For prestressed concrete voided slabs and box beams. Pretensioning can be further classified into two categories such as linear pretensioning and circular pretensioning. This document was prepared and used for designing actual vehicular bridge. Pdf design of twoway prestressed slabs piotr sokal academia. Pci handbook precast prestressed concrete institute. Prestressing reinforcement doesnt necessarily make concrete stronger. Pti 3 structural material types structural steel prestressed concrete reinforced concrete pre. Precastprestressed concrete portland cement association. It is an essential resource for every precast concrete project. A slab strip of unit width is analysed using simple beam theory. Pretensioned prestressed concrete bridge beams and bridge. For the specified concrete material of 40 mpa cube strength. Pretensioning is accomplished by stressing wires or.
The idea of prestressed concrete has been around since the latter decades of the 19th century, but its use was limited by the quality of the materials at the time. Solid slab deck infill deck, beam and slab deck, voided bridge deck. An attempt was made to include not only necessary readings but also most recent. In reinforced concrete members, the prestress is commonly introduced by. The superstructure design includes the following elements. Design of ultra high strength prestressed concrete beams with concrete strengths up to 200mpa is presented with examples. A 2 2area 2 a c 2 2 posttensioned concrete design table 11 list of symbols used in the aci 31808 code cp area enclosed by the outside perimeter of the section, in a g gross area of concrete, in a 2 l total area of longitudinal reinforcement to resist torsion, in a o area enclosed by the shear flow path, sqin a oh area enclosed by the centerline of the outermost closed. Pstrs12, prestressed beam analysis was a prestressed concrete beam analysis program used to check optional beam designs when given the end and centerline strand patterns and other design parameters. This performance is the result of the practices reported herein, conformance with aci 31805, building code requirements for structural concrete,1. Doing business with nysdot businesscenter engineering cadd info drawings bridge detail bd sheetsusc pc prestressed concrete beams and slab units usc prestressed concrete beams and slab units usc.