File Name: practical design and detailing of steel column base plates .zip
Computerized Structural Design, S. This book or any part thereo must not be reproduced in any orm without the written permission o the publisher. The inormation presented in this publication has been prepared in accordance with recognized engineering principles and is or general inormation only. While it is believed to be accurate, this inormation should not be used or relied upon or any speciic application without competent proessional examination and veriication o its accuracy, suitability, and applicability by a licensed proessional engineer, designer, or architect.
The publication o the material contained herein is not intended as a representation or warranty on the part o the merican Institute o Steel Construction or o any other person named herein, that this inormation is suitable or any general or particular use or o reedom rom inringement o any patent or patents. Caution must be exercised when relying upon other speciications and codes developed by other bodies and incorporated by reerence herein since such material may be modiied or amended rom time to time subsequent to the printing o this edition.
The Institute bears no responsibility or such material other than to reer to it and incorporate it by reerence at the time o the initial publication o this edition. Special appreciation is also extended to Carol T. Williams o Computerized Structural Design or typing the manuscript. ISC would also like to thank the ollowing individuals who assisted in reviewing the drats o this Design Guide or their insightul comments and suggestions.
Carter Brad Davis Robert O. Disque James Doyle Richard M. Drake Samuel S. Eskildsen Daniel M. Falconer Marshall T. Ferrell Roger D. Hamilton John Harris llen J. Harrold Donald Johnson Georey L. Kulak Bill R. Segui David F. Violette Floyd J. Vissat v. Base Plate Material Selection These connections are used in buildings to support gravity loads and unction as part o lateral-load-resisting systems. In addition, they are used or mounting o equipment and in outdoor support structures, where they may be aected by vibration and atigue due to wind loads.
Base plates and anchor rods are oten the last structural steel items to be designed but are the irst items required on the jobsite. The schedule demands along with the problems that can occur at the interace o structural steel and reinorced concrete make it essential that the design details take into account not only structural requirements, but also include consideration o constructability issues, especially anchor rod setting procedures and tolerances. The importance o the accurate placement o anchor rods cannot be over-emphasized.
This is the one o the key components to saely erecting and accurately plumbing the building. The material in this Guide is intended to provide guidelines or engineers and abricators to design, detail, and speciy column-base-plate and anchor rod connections in a manner that avoids common abrication and erection problems. This Guide ollows the ormat o the ISC Speciication, developing strength parameters or oundation system design in generic terms that acilitate either load and resistance actor design or allowable strength design SD.
Column bases and portions o the anchorage design generally can be designed in a direct approach based on either or SD load combinations. The one area o anchorage design that is not easily designed by SD is the embedment o anchor rods into concrete. This is due to the common use o CI ppendix D, which is exclusively based on the strength approach or the design o such embedment.
Other steel elements o the oundation system, including the column base plate and the sizing o anchor diameters are equally proicient to evaluation using or SD load methods. In cases such as anchors subjected to neither tension nor shear, the anchorage development requirement may be a relatively insigniicant actor. The generic approach in development o oundation design parameters taken in this Guide permits the user a choice to develop the loads based on either the or SD approach.
Many o the equations shown herein are independent o the load approach and thus are applicable to either design methodology. These are shown in singular ormat. Other derived equations are based on the particular load approach and are presented in a side-by-side ormat o comparable equations or or SD application. The typical components o a column base are shown in Figure 1.
Material selection and design details o base plates can signiicantly aect the cost o abrication and erection o steel structures, as well as the perormance under load. Relevant aspects o each o these subjects are discussed briely in the next section. Not only is it important to design the column-base-plate connection or strength requirements, it is also important to recognize that these connections aect the behavior o the structure.
Models comprising beam or truss elements typically idealize the column base connection as either a pinned or ixed boundary condition. Improper characterization can lead to error in the computed drits, leading to unrecognized second-order moments i the stiness is overestimated, or excessive irst-loor column sizes i the stiness is underestimated. I more accurate analyses are desired, it may be necessary to input the stiness o the column-base-plate connection in the elastic and plastic ranges, and or seismic loading, possibly even the cyclic orce-deormation relations.
The orces and deormations rom the structural analyses used to design the column-baseplate connection are dependent on the choice o the columnbase-plate connection details.
Figure 1. Column base connection components. Base Plate Materials Thickness t p t p 4 in. STM 36 [a] Preerred material speciication The vast majority o building columns are designed or axial compression only with little or no uplit. For such columns, the simple column-base-plate connection detail shown in Figure 1.
The design o column-base-plate connections or axial compression only is presented in Section 3. The design is simple and need not be encumbered with many o the more complex issues discussed in ppendix, which pertains to special structures. Column base plate connections are also capable o transmitting uplit orces and can transmit shear through the anchor rods i required.
I the base plate remains in compression, shear can be transmitted through riction against the grout pad or concrete; thus, the anchor rods are not required to be designed or shear. Large shear orces can be resisted by bearing against concrete, either by embedding the column base or by adding a shear lug under the base plate. Column base plate moment connections can be used to resist wind and seismic loads on the building rame.
Moment at the column base can be resisted by development o a orce couple between bearing on the concrete and tension in some or all o the anchor rods. This guide will enable the designer to design and speciy economical column base plate details that perorm adequately or the speciied demand. The objective o the design process in this Guide is that under service loading and under extreme loading in excess o the design loads, the behavior o column base plates should be close to that predicted by the approximate mathematical equations in this Design Guide.
Historically, two anchor rods have been used in the area bounded by column langes and web. Recent regulations o the U. Occupational Saety and Health dministration OSH Saety Standards or Steel Erection OSH, Subpart R o 9 CFR Part require our anchor rods in almost all column-base-plate connections and require all columns to be designed or a speciic bending moment to relect the stability required during erection with an ironworker on the column.
This regulation has essentially eliminated the typical detail with two anchor rods except or small posttype structures that weigh less than lb e. In addition to the OSH regulations, there has been signiicant research and improved design guidelines issued subsequent to the publication o Design Guide 1 in The CI Building Code Requirements or Structural Concrete CI, 00 has improved provisions or the pullout and breakout strength o anchor rods and other embedded anchors.
Design guidance or anchor rods based on the CI recommendations is included, along with practical suggestions or detailing and installing anchor rod assemblies. These guidelines deal principally with cast-inplace anchors and with their design, installation, inspection, and repair in column-base-plate connections. Based on cost and availability, the materials shown in Tables. Since STM 36 plate is readily available, the plates can oten be cut rom stock material.
There is seldom a reason to use high-strength material, since increasing the thickness will provide increased strength where needed. Plates are available in 8-in. The base plate sizes speciied should be standardized during design to acilitate purchasing and cutting o the material. When designing base plate connections, it is important to consider that material is generally less expensive than labor and, where possible, economy may be gained by using thicker plates rather than detailing stieners or other reinorcement to achieve the same strength with a thinner base plate.
For example, in the design o a crane building, the use o a seat or stool at the column base may be more economical, i it eliminates the need or large complete-joint-penetration CJP groove welds to heavy plates that require special material speciications. Most column base plates are designed as square to match the oundation shape and more readily accommodate square anchor rod patterns.
Exceptions to this include momentresisting bases and columns that are adjacent to walls. Many structural engineers have established minimum thicknesses or typical gravity columns. For posts and light HSS columns, the minimum plate thickness is typically in. Section M. Gouges deeper than x in. Because ree edges o the base plate are not subject to tensile stress, these requirements are not mandatory or the perimeter edges; however, they provide a workmanship guide that can be used as acceptance criteria.
Generally, round-bottom grooves within the limits speciied are acceptable, but sharp notches must be repaired. Finishing requirements or column bases on steel plates are covered in Section M. Steel bearing plates over in. Steel bearing plates over 4 in. Two exceptions are noted: The bottom surace need not be milled when the base plate is to be grouted, and the top surace need not be milled when CJP groove welds are used to connect the column to the baseplate.
I the gap exceeds z in. Shims need not be other than mild steel, regardless o the grade o main material. While the ISC Speciication requirements or inishing are prescriptive in orm, it is important to ensure that a satisactory contact bearing surace is provided.
By applying the provisions o Section M4. Standard practice is to order all plates over approximately 3 in. Typically, only the area directly under the column shat is milled.
The base elevation or setting the column is determined in this case by the elevation at the bottom o the column shat with the grout space and shims adjusted accordingly.. Welds attaching base plates to columns are oten sized to develop the strength o the anchor rods in tension, which can most oten be achieved with a relatively small illet weld. For example, a c-in. The use o the weld-all-around symbol should be avoided, especially on wide-lange shapes, since the small amount o weld across the toes o the langes and in the radius between the web and lange add very little strength and are very costly.
For most wide-lange columns subject to axial compression only, welding on one side o each lange see Figure.
This joint is created by welding a steel plate to the bottom end of the column, which is in turn connected to the foundations through anchors. The joint can include several plates, stiffeners or shear anchor. You can customize each joint element using the available buttons from the Joint elements panel. All changes made in every window can be viewed in real time. For example, you can define the geometry of the plates and stiffeners, set the configuration of the anchors and customize the welds thickness, type and quality for each part of the joint or add different elements.
The information presented in this publication has been prepared in accordance with recognized engineering principles and construction practices and is for Two general approaches are adopted for the design of base plates subjected to axial load and bending moment. Step 7 Ultimate load of columns. Further assistance in the selection of the size of a column is given in. Table Design and Construction Detailing for.
Text of Practical Design and Detailing of Steel Column Base Plates · 1 Anchor Bolt Position Mislocation · 2 Rotated Anchor Bolt Patterns · 3 Anchor Bolts Set.
The present chapter aims to give an overview of the recent progress made on the investigation of column bases with end plates and embedded column bases. The column base detailing, tolerances and modelling by application of the component method to column bases are herein introduced. The particular components are also described including their influence on the connection behavior.
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Бринкерхофф хотел было уже взять следующий документ, но что-то задержало его внимание. В самом низу страницы отсутствовала последняя СЦР. В ней оказалось такое количество знаков, что ее пришлось перенести в следующую колонку. Увидев эту цифру, Бринкерхофф испытал настоящий шок. 999 999 999.
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Сьюзан это показалось разумным.