Presents the basics of seismic-resistant design of concrete structures. * Provides a major focus on the seismic design of precast bracing systems. Seismic. PDF | This preliminary paper on the seismic design of precast concrete and Analytical Modeling of Prefabricated Reinforced Concrete Sandwich Panels. Topic 11 is the seismic design of reinforced concrete structures, primarily Precast shear walls: system limitations for various Seismic Design Categories.
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Size Report. DOWNLOAD PDF Seismic Design of Reinforced Concrete and Masonry Buildings. Read more Design of Prestressed Concrete · Read more. paper emphasizes seismic design; the aim of the design Examples of recent precast concrete buildings using the .. place reinforced concrete construction. fib Bulletin Seismic design of precast concrete building structures iii This PDF copy of fib Bulletin 27 is intended for use and/or distribution only by National Member .. cast-in-place reinforced concrete is not considered in this report.
These provisions have demonstrated that how Hamid25 adopted that approach of structural flexibility the seismic performance of precast systems can be and prestressed unbonded tendons in precast hollow- improved.
Precast provisions and guidelines in Indian perspective. One of the main reasons of collapse of floors continuous reinforcement through the support. In this were loss of seat due to failure of support system, poor case the unit will need transverse reinforcement also to connections, excessive deformation of support system behave as a T-beam.
Typical detail of the damage of seat of a floor resting on wall or beam support due to the movement is shown in Fig. Movement Crack in topping Cast in place reinforced concrete topping Spalling at end of precast concrete floor unit Spalling of cover concrete Precast concrete beam Fig.
Earthquake vertical accelerations add on to this action. Floors with topping are also failed during these earthquakes when the top reinforcement could not transfer the shear force from the precast flooring to the supporting beam as shown Fig.
A comparison of the clauses related to the issues Figures 4 a and 4 b show the alternative special responsible for failure of precast concrete structures reinforcing to transfer shear force and support precast during earthquakes is attempted in following sub- concrete floor units in the event of loss of bearing.
The clauses common to precast and cast-in- Continuous bottom reinforcement will transfer shear place concrete structures are not considered here.
The other Precast Concrete Floor Systems alternative with hanger stirrups in the vicinity of support can also help in the transfer of shear force. Another A few common types of pre-cast concrete floors used possibility to support the floor unit in such event can be in New Zealand are discussed: i flat slab floor ii to design the floor as a T-beam by providing an additional hollow-core concrete slab floor and iii double-tee tie at the middle to transfer floor load by providing floor.
Flat slab floors Fig. It consists generally of a series precast concrete diaphragms to components of the of 75 mm thick precast, prestressed concrete slabs with vertical primary lateral force resisting systems. The slabs are usually 1. These floor The codes permit a variety of methods for connecting slabs can span up to 18 m at mm depth and members in plane and out of plane.
These are grouted provide a working platform immediately after being joints, shear keys, mechanical connectors, reinforcing positioned. Hollowcore slabs are generally un-propped steel connections, reinforced topping, or a combination during the casting of the topping.
Concrete topping on of these.
Codes suggest a minimum bearing length after precast floors can be of about 65mm to 75mm. However this length should not be less than 50mm for solid or hollowcore slabs and 75mm for beams or stemmed members as per ACI NZS has a small change that for hollowcore slab this length is 75mm.
Codes have suggested to have a clear distance of 15mm from the unarmored edges and make allowances for concrete cover. Required length of bearing at the support of a member in relation to its clear span is illustrated in Fig. NZS suggests in particular for hollow-core floor that the floor Another type of precast floor used for long spans is a should be mounted on low friction bearing strips with double tee unit consisting of two prestressed ribs with a coefficient of friction less than 0.
The ribs width of 50mm. Double Tees typically span up to 19 m, and provide a safe platform, directly Structural integrity is necessary to improve the after placing, for subsequent work.
This also helps to Three types of support for precast concrete hollow-core avoid collapse of the structures in the event of damage to or solid slab flooring units seated on precast beams, major supporting element or an abnormal loading event identified by the New Zealand Guidelines are given by maintaining overall stability. Codes suggest provisions in Park It is desirable to resist the relevant design for precast concrete structures to achieve structural forces by providing adequate connections by means integrity to the same extent as of monolithic structures.
To overcome this structure to effectively tie precast concrete elements incompatibility issue and avoid the brittle failure, NZS together. This will also achieve the diaphragm action have suggested for the precast floor systems to of the floor and a seismic load path in the structure. The code has Recommendations are made for minimum provisions suggested the connection details that have performed of geometry and reinforcement detailing of horizontal well in analytical and experimental investigations.
Codes have suggested the design and detailing of these systems to be same as cast-in-place system with taking particular care in designing the connection to emulate similar behaviour.
Precast concrete frame systems composed of concrete elements with ductile connections are expected to experience flexural yielding in connection regions. ACI has recommended the reinforcement provisions and type of Fig.
Diaphragm Action The arrangement commonly used in New Zealand for strong column-weak beam designs with the Precast concrete floor could not transmit in plane objective to achieve behaviour emulating a monolithic force induced by earthquakes to lateral load resisting structure is presented by Park Arrangement of precast system adequately and failed during past earthquakes. The diaphragms similar to the cast-in-place diaphragms. Codes have suggested the minimum thickness far face of the cast-in-place joint core.
For System 2, of topping to be 50mm for 20mm cover and 25MPa the vertical column bars of the column below the joint strength of concrete. It is further needed to be increased protrude up through vertical ducts in the precast beam depending on the size of reinforcement and clear cover unit, where they are grouted, and pass into the column to be used. The columns of the precast elements of System ACI recommends minimum thickness 3 are connected by longitudinal column bars which of topping slabs placed on precast concrete or roof protrude into steel sleeves or ducts in the adjacent elements, acting as structural elements and not relying elements and are grouted.
The beams are connected on composite action to be NZS relates the using cast-in-place joint at mid span.
Capacity minimum thickness of topping with the diameter of bars design procedure for these three systems ensures that used. Minimum thickness of topping for 6, 10, 12 and yielding of the column bars at the connections is kept 16 mm stirrups, ties or spirals used is 50, 75, 90 and to a minimum.
Figure 9 shows a further system using mm respectively. It is also suggested that if the cover is pretensioned prestressed concrete U-beams and cast- greater than 20mm then the thickness of topping should in-place reinforced concrete. Figure 10 shows a typical be increased by the amount of additional cover. Connections between the precast panel and the Elongation of plastic hinge regions in beams result cast-in-place foundation system are the most critical in the deformation incompatibility of floors with the connections in precast concrete structures.
In tall support system. This phenomena is much observed in buildings, other wall panel-to-panel connections are the collapse of hollow-core floors in Armenian also equally important.
The full-height through the structural element. ACI grout provides continuity for compressive forces across recommends welded and lapped splices to be located the joints and bars provide continuity for tensile forces. Overlapping bars can also be made made continuous with the lapped bars in conduit. In such case wall panel is first erected and held high. Loose vertical bars in the panel being erected are spliced to protruding bars from below.
Panel is then lowered to correct elevation and conduit is grouted by gravity flow from top or optional grouting port from bottom of panel. Special mechanical splices Type 2 are recommended to be used by ACI A typical mechanical splice for connection of walls and floors is shown in Fig. Many other possible connection details are available in the report ACI Ideal locations for monolithic connections in precast concrete frame systems are the sections of minimum moments or point of inflection.
H-shaped and cruciform frame systems have connections at the points of inflection likely to occur under lateral loading. Connections are typically similar to wall and floor connections shown in Figs. In that case all the reinforcement crossing beam and column will be spliced. A typical column-to-column connection through conduits installed in a beam is shown in Fig. Conduit diameter should be two to four times the bar diameter for tolerance in field erection.
This Fig. The ductile-jointed hybrid connections in precast These connections are detailed to resist the earthquake systems are permitted by codes with proper field, ana- forces and deformation emulating cast-in-place lytical or experimental evidences of good performance. Some salient points related to seismic design provisions as given in IS are as under: 1. Code suggests designing the large panel prefab structures which is stable for all possible situations of precast construction.
Joints between members are recommended to be designed to resist the forces acting on them Fig. They should also be able to accommodate the deviations tolerances in the dimensions of the panels during production and erection.
It is recommended to provide the tie-beams at each floor level along all structural walls and along the perimeter of the building to obtain a monolithic action of walls and floors, and to limit the possibility of progressive collapse.
Tie-beams may be designed as monolithic ones constructed at site during assembly or hidden ones constructed by connecting the bars placed on the floor panels. Analysis and design of floors and walls is recommended to be performed as per IS The above provisions indicate to achieve the structural integrity and monolithic behaviour of Precast concrete systems composed of elements large panel prefab structures.
Studying the code and joined using strong connections are recommended to comparing with other international standards it is found be designed using capacity design concept. Examples that following points need attention for reconsideration of strong connections for beam-to-beam, beam-to- or revision to achieve the good performance in seismic column and column-to-footing are illustrated by ACI zones: These connections are intended to experience 1.
The code permits the large panel prefab up to 6m flexural yielding outside the connections. Minimum specifications for anchorage, bearing wall panels or wall panels and the foundation. In high seismic zones only solid slab concrete design concept. Specifications for joints detailing and ties are not areas. A review of seismic performance and behaviour sufficient when compared to other national codes of precast concrete structures indicates that the of practice.
Detailed study in last section is helpful buildings constructed and designed incorporating in specifying provisions to Indian standard in this seismic design concepts performed remarkably well.
This paper summarises the historical perspective on 5. Deformation compatibility provision for flooring the performance of precast concrete structures and system needs to be incorporated in the Indian an extensive literature on experimental studies to standard in line with NZ standards. A brief review of provisions 6. Welding in seismic joints is not recommended in perspective. It is concluded that the provisions in IS high seismic zones and should be avoided; however for seismic design of large panel prefab mechanical connections with ductile welds are buildings are insufficient in general and from the permitted with appropriate over strength.
It is recommended 8. Clarity in all the provisions with a commentary to include a chapter on general provisions on precast explaining the behaviour is needed to be concrete element and structures in IS and incorporated in the code. A guideline for connection details for high seismic elements and structures in IS As a future regions emulating cast-in-place construction is scope of this paper, each precast concrete element can be needed to be prepared. IS: and other precast codes in India are there design and international codes of practice.
Need of for small precast components only. Based on the experimental investigations provide the same level of ductility as that of and experiences on seismic performance a state-of-the- a monolithic reinforced concrete construction art report can be prepared for the analysis and design of during or after an earthquake.
There is no code for the construction of precast frame buildings in India. He also wishes to express in IS and special provisions on seismic his gratitude to S.
Englekirk, Robert E. Martin, jose Ma. John for precast prestressed concrete building structures Wiley and Sons Inc.
Earthquake Spectra, Pekau, O. Matthews, J.
Ochs, Jay E. New Zealand, Lindsay, R. Worked Examples for the Design of Concrete Buildings. Design of Prestressed Concrete. Design of Concrete Structures.
Design of concrete structures. Seismic Design and Retrofit of Bridges. The Seismic Design Handbook. Structural Analysis and Design of Tall Buildings. Reinforced Concrete-Analysis and Design. Structural Concrete: Theory and Design.
Design of Prestressed Concrete Structures. Fundamentals of 3D Seismic Survey Design. Vibration of Buildings to Wind and Earthquake Loads. Recommend Documents. Seismic Design of Buildings and Bridges