seismic design of composite shear walls & frames - مقاومة الرياح والزلازل...
TRANSCRIPT
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Dr Youssef Hammida
SEISMIC DESIGN OF COMPOSITE
SHEAR WALLS & FRAMES
مقاومة الریاح والزالزل جدران
واطارات مركبة قصیة
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The structural system of a building is a complex three-dimensional assembly of interconnected discrete or continuous structural elements.
The primary function of the structural system is to carry all the loads acting on the building effectively and safely to the foundation.
The structural system is therefore expected to:
Carry dynamic and static vertical loads. Carry horizontal loads due to wind and earthquake effects. Resist stresses caused by temperature and shrinkage effects. Resist external or internal blast and impact loads. Resist, and help damp vibrations and fatigue effects.
steel-concrete composite systems for buildings are composed of concrete components that interact with
structural steel components within the same system
COMPOSITE ACTION BETWEEN STRUCTURAL ELEMENTS IN BUILDINGS
Steel and concrete are the major materials used in composite systems.
Although they have several dissimilar physical characteristics, it is possible to use them together, beneficially, in different ways.
A number of systems have been developed in the last few decades which successfully combine steel and concrete. The following composite systems have been used for a wide range of buildings: الجمل المركبة للحموالت األفقیة والشاقولیة عانوا
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1. Frame structure جملة االطارات 2. Shear wall structure جملة حدران القص 3. Staggered shear wall system ناوبة تجدران القص الم 4. Tubular system الجمل الشبكیة واالنبوبیة
بالطات األسقف المركبة
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المقاطع الجاھزة والبالطات المركبة
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COMPOSITE MEMBERS العناصر المجمعة المركبة
To get an idia into the composite behavior of structural steel and
reinforced concrete systems, it is to study common techniques of
compositing the following structural units:
1. Composite slabs بالطات األسقف والطواق
2. Composite beams الكمرات المركبة
3Composite columns األ عمدة المركبة
4. Composite diagonals العناصر القطریة المائلة المركبة
5. Composite shear walls جدران القص المركبة
Composite slabs البالطات المركبة In steel buildings, the use of high-strength, light-gauge (16–20 gauge)
metal deck with concrete topping has become a standard (see Figure 2.1).
The metal deck has embossments pressed into the sheet metal to achieve
composite action with concrete slab.
When the concrete hardens, the steel deck becomes the tension reinforcement.
The resulting composite slab acts as a diaphragm providing for the
horizontal transfer of shear forces to the vertical bracing elements.
Furthermore, it actsas a stability bracing for the compression flange of
steel beams.
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The shear forces in the diaphragm mostly occur in the concrete slab
because the in-plane stiffness of concrete slab is significantly more than that
of the metal deck. Thus, the horizontal forces must transfer from the slab to
the beam top flange through welded studs
فقیة من الریاح والزالزل تنتقل من البالطة الى الجسوراال القوى
ت بواسطة بسامیر القص ثم األ عمدة واألساساوالكمر
الجسر والبالطة -اومة القص الواصلة بین الكمرة تركیب مسامیر مق
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تركیب الواح الصاج ومسامیر القص
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Composite Girders الجسور- الكمرات المركبة
Consider a typical steel moment frame consisting of beams rigidly connected to
columns.
Therefore, to limit the sway under lateral loads, it is more prudenteffecting
to increase the girder stiffness rather than the column stiffness.
Although frame beams are designed as non-composite, it is a usual
practice to use shear studs at a nominal spacing of say, 12 in.
The shear connectors primarily provided for the transfer of diaphragm
shear also increase the moment of inertia of the girder.
The increase, however, is not for the entire length of the girder because
under lateral load sit bends in a reverse curvature.
Since concrete is ineffective in tension, the increase in the moment
of inertia can be counted on only in the positive moment region.
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الكمرات المركبة تكون مدفونة بالخرسانة
او ظاھرة اسفل البالطة ویحب ان تكون صلبة
عند نقاط اساتادھا مع البالطة
اسفل البالطةقد یتواجد دك معدني
او سولد سالب مع الكمرة المعدنیة
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الجسور مع األعمدة الفوالذیة –تفاصل استناد الكمرات
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بزوایا مثبتة في الجدار تفاصبل اتصال الكمرة الجسر المعدني مع جدار القص
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بالدعمات العامود عقدةزیادة صالبة
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خرسانة محیطیة كمرة -اتصال الجائز الشبكي مع الجسر
Composite Columns األعمدة المركبة
Two types of composite columns are used in buildings (see Figure 2.2a
and b).
The first, commonly referred to as encased composite column, consists of a
steel core surrounded by a reinforced concrete envelope.
The second referred to as filled composite column consists of a steel pipe or
tube filled with high-strength concrete.
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In the first type, the steel core, most usually a wide flange section
placed within the reinforced concrete column is designed as an erection
column to carry construction loads only.
Conceptually the behavior of a composite column is similar to a reinforced
concrete column, if the steel section is analytically replaced with an
equivalent mild steel reinforcement.
In fact, this concept provides the basis for generating the interaction
diagram for the axial load and moment capacities of composite columns.
Compositing of exterior columns by encasing steel sections with concrete is
by far the most frequent application of composite columns. The reasons are
entirely economic, because forming around interior columns is quite
involved and is not readily applicable to jump forms.
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Exterior columns, on the other hand, are relatively open-faced: formwork
can be “folded” around steel columns for placement of concrete, then
unfolded and jumped to the next floor..
ةوتشاریك معدنیة في الخرسان مركب عمود معدني
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الغالف الخارجي المعدني اعمدة مركبة
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مع االطارات وتصمیم اشكال األعمدة المركبة
العامود القوي والجائز الضعیف
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هذا النظام یجمع بین الصال�ة . المر��ة الفوالذ�ة المغلفة هي احد األنما� الشائعة لألعمدةاألعمدة
التش�یل للخرسانة المسلحة و�ین القوة وسرعة اإلنشاء للفوالذ اإلنشائي ةوقابل�
ومقاوم اقتصاد� منشأ الى للوصول
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مركبة اطارات اعمدة تصمیم الكود المصري
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األعمدة المركبة الطریقة المرنةتصمیم
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تصمیم األعمدة المركبة كود امریكي
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محورین على عمدة مركبة عزم انعطاف اتجاھینا
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عزم باتجاھین تصمیم العامود المركب من مخطط اآلباك
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Composite diaGonals العنصر القطري المائل المركب
As a part of a vertical truss, diagonals in a braced frame resist lateral forces
primarily through axial stresses.
As a result, braced frames are more economical than moment-resisting
frames.
However,their use is often limited, because of potential interference with
architectural planning concerns
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FIGURE 2.3 Japanese composite construction details: (a) beam column
intersection; (b and c) composite column with welded ties;
مقاوم للعزوم تفصیل عقدة اطار مركب
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Composite shear Walls الجدران القصیة المركبة
One of the most common uses of composite shear walls is in steel frame
buildings, in which selected bays are infilled with a reinforced concrete wall. In essence, this results in a reinforced concrete
shear wall with structural steel boundary elements and coupling beams (see
Figure 2.5). ةستعمال الجدران القصیة المركبة في األبنیة المعدنيا If the coupling beams were pin-connected at each end to the boundary
elements, they would be ineffective in improving the lateral resistance of the
wall. This is because the two wall piers would
resist lateral loads independently. On the other hand, if the coupling beams are infinitely stiff, they
would fully couple the two piers coercing them to work as a single unit. If the
coupling beam stiffness is in between the two extremes, as is the case in most
buildings, the corresponding response will also be in between the two limits. Composite steel plate diaphragms are appropriate when extremely high
shear forces must be transferred from one system to another at the base of
the building. An example of this use may be
found again in the Bank of China Tower, Hong Kong, in which the entire
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base shear is transferred from the building perimeter to the building core at
the base, via a steel-plated floor diaphragm. Possible details of composite shear plate walls are shown in Figure 2.6. In
these details, structural steel framing surrounds the steel plates with the
entire steel assembly encased in reinforced
استعمال اعمدة مركبة ضمن اطارات معدنیة فوالذیة ستیل مقاومة للعزوم
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نھ واحد ووجھيقصي مركب بصفائح فوالذیة على وج جدار
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والوسط جدار قصي مركب مع اعمدة زیادة المطاوعة في النھایات
لحام تشاریك القص
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عمدة نھایات الجدار القصي مركبة مع بروفیل فوالذيا
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coupling Beam وتشكل المفصل اللدن دار قصي مركب مع كمرة فوالذیةج
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الجدران القصیة المركبة مع بروفیالت فوالذیة مدفونة مع الخرسانة المسلحة
The concrete advantages in terms of higher stiffness, good fire protection,
buckling prevention, recommends composite elements made by steel and
concrete to be used in high-rise buildings placed in seismic areas.
The steel concrete composite shear walls are used as lateral loads resisting
systems for high-rise buildings as an alternative to reinforced concrete
shear walls.
Composite steel concrete shear walls are structural walls where at the
boundary elements of the wall are encased steel profiles.
تستعمل الجدران القصیة المركبة مع ابنیة الخرسانة وابنیة
ةفوالذیة بنفس الوقت لمقاومة حموالت شاقولیة باالضاف
لحموالت الریاح والزالزل
Composite Shear Walls with
Encased Profiles
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يبروفیل فوالذ جدرار قصي مركب خرسانة مسلحة محاط
وبسامیر وصل قصیة
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تفاصیل اشكال جدران خرسانة قصیة مركبة مع انواع البروفیل الفوالذي
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انواع واشكال جدران الخرسانة المسلحة المركبة
وتموضع الصفائح والبروفیل المعدني
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الجدران القصیة المركبة مسیقة الصنع
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الحدران القصیة المركبة ومسبقة الصنع
ماطارات فوالذیة خاصة مقاومة للعزوضمن
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تفاصیل اتصال الحدران المركبة الخرسانیة والفوالذیة
مع عناصر النھلیات من البروفیل الفوالذي
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Composite shear wall assembly could speed
construction of steel frames
The sandwich, called a dual-plate composite shear wall
because its steel-plate walls are filled with lightly reinforced
concrete, is not for use only in seismic zones.
“It is a great system for multihazard mitigation because it is
good for seismic, wind and gravity loads as well as blast
resistance,
”الجدار القصي المركب بروفیل صفائح فوالذیة خارجیة
وخرسانة مسلحة
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COMPOSITE SUBSYSTEMS
These systems may be categorized as follows:
انواع الجمل القصیة الفوالذیة والمركبة
1. Composite moment frames
2. Composite braced frames
3. Composite eccentrically braced frames
4. Composite shear wall-frame interacting systems
5. Composite tube systems
6. Vertically mixed systems
7. Mega frames with super columns
8. High-efficiency structures
Composite moment Framesاالطارات المركبة الخاصة المقاومة للعزوم
Refer to Figure 2.9 for schematics of a composite moment frame
consisting of steel beams and composite columns.
The columns may consist of either concrete encased or filled composite
columns, with moment connected steel beams.
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اطارات فوالذیة خاصة مقاومة للعزوم واعمدة مركبة
وتحقیق العامود القوي والجائز الضعیف
Intermediate and special moment frames must satisfy detailing
requirements that are more stringent than those for ordinary moment
frames
The reason is to assure a ductile response when these buildings are
pushed beyond elastic limit in a major seismic even
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عقدة انصال مقاومة للعزوم و كمرات فوالذیة وعامود مركب
تحقبق العامود القوي
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Seismic provisions of AISC 341-05 recognize three types of
composite moment frames:
1. Ordinary moment frames
2. Intermediate moment frames
3. Special moment frames المقاومة للعزوم المركبة الكود األمریكي وانواع االطارات
Special Moment Frames- االطارات المركبة الخاصة
The term “special” refers to the characteristics of the frame in which the
members and connections are designed and detailed to provide maximum
ductility and toughness, implying excellent energy dissipation and
seismic performance during severe earthquake shaking.
In recognition of the ductility, seismic provisions allow a maximum
reduction in the design base shear.
Because of the recognized ductility and the limited interference with
architectural planning, special moment frames are one of the most
commonly used lateral systems.
على االطارات المركبة رات الفوالذیة والخرسانیةاتطبق نفس اشتراطات االط
من حیث المطاوعة وتشكل المفصل اللدن
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وقاعدة العامود القوي والجائز الضعیف
ویؤخذ عامل المطاوعة R او زیادة المقاومة من الجداول
Composite special moment frames are similar in configuration to
ordinary moment-resisting frames.
As in steel or concrete systems, more stringent detailing provisions are
required to increase the system’s ductility and toughness.
The commensurate reduction in design lateral force is very
similar to that in steel or concrete special moment frames.
The design intent is to confine inelastic hinging in beams, while the
columns and connections remain essentially elastic.
The design base shear prescribed for this system is similar to the special
moment-resisting frame systems of steel or reinforced concrete.
Likewise, no limitations have been placed on their usage in buildings
assigned
to a higher SDC.
special moment-resting frames attempts to provide the maximum
possible frame ductility, toughness, and energy-dissipation capacity.
This requirement results in more stringent provisions for member and
joint detailing.
Generally these frames are designed to limit inelastic action to the
beams, with the intent of preventing potential yielding in columns and
connections.
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The design should include the strong column-weak beam concept. For
composite columns, transverse reinforcement requirements should be
equivalent to those required for reinforced concrete columns in special
moment-resisting frames.
Special details are required to satisfy closed-hoop and cross-tie
requirements for encased composite columns.
االطارات المركبة اعمدة ترتیبات خاصة لزیادة المطاوعة قي
and lateral torsional buckling, allowing the beams to develop their full
plastic flexural capacity.
However, steel flanges connected to concrete slabs with shear
connectors are exempted from this provision. This is because lateral
torsion and local buckling are inhibited by the shear connectors and
concrete slab.
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he design of composite frames is not significantly different from the
procedures for structural steel or reinforced concrete moment frames
رات الخاصة المركبةامطاوعة وممطولیة االط
Encased composite columns should have a minimum ratio of structural steel gross
column area of 4%. The shear strength of columns generally ignores the contribution of concrete.
However, the contribution of the shear strength of the reinforcing ties
based on an effective shear width bf of the section, as noted in Figure 2.12, is
permitted. For filled composite columns; it is conservative to neglect the
contribution of concrete to the shear strength of the column.
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Where shear strength becomes critical, the composite column may be treated as a
reinforced concrete column with the steel considered as shear einforcement. Transfer of forces between structural steel and reinforced concrete should be made
through shear connectors, ignoring the contribution of bond or friction. المقطع المتشققالتؤخذ مقاومة الخرسانة للقص في ومنطقة تشكل المفصل اللدن
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Composite Braced Framesعناصر الدعم المائلة والقطریة المركبة two types of composite braced frames are recognized in AISC 341-
05/10: (1) Concentric bracing, where various bracing members meet at a
common point; and (2) a relatively new form of braced frame called eccentric brace. this system combines the ductility of moment frames with the high
stiffness of concentrically braced frames طریة الفوالذیة الدعم المائلة والقعناصر
واألعمدة المركبة
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Composite brace design in concentrically braced frames must recognize
that these elements are expected to provide for the inelastic action during
large seismic overloads. Braces consisting of concrete encased steel elements should include
reinforcing and confinement steel sufficient to provide the intended
stiffening effect even after the brace has buckled during multiple cycles
of seismic motion. As a result, it is recommended that these elements should meet detailing
requirements similar to those for composite columns. Composite braces in tension should be designed considering the
resistance provided only by the steel. المركب الخرسانة جمیع حاالت التدعیم المائل
ویجب االنتباه عند تواجدھا في مناطق تشكل المفصل اللدن -ال تشارك في مقاومة فوى الشد
والعمل في مجال اللدونة
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Brace buckling and the resulting large rotation demands at the brace ends
should be considered in connection detailing.
Schematic details of brace to encased composite column are
shown in Figure 2.14a and b.
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Composite Eccentrically Braced Frames مركزیةعناصر االطارات المائلة المركبة الال
figure 2.15. In general, beams in composite eccentrically braced frames
consist of structural steel sections. Any concrete encasement of the beam should not extend into the link
regions where large inelastic action is expected to develop (see Figure 2.16a). Columns and braces can be of either structural steel or
composite construction. The analysis, design, and detailing of the system is similar to that for steel
eccentrically braced frames since the force transfer mechanisms between the steel and concrete rely on
bearing and shear friction, special attention must be paid to the design of
connections to realize the intended inelastic action intheductile links
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عناصر الدعم المائلة الال مركزیة
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Composite brace design in eccentrically braced frames must recognize that
these members are intended to remain essentially elastic during large seismic
overloads.
The design strength must consider the yielding and significant strain
hardening that can occur in properly designed and detailed
link elements.
Both axial and bending forces generated in the braces by the strain-hardened
link عناصر الدعم المائلة والقطریة یبقى عملھا ضمن المنطقة المرنة
والیتشكل فیھا مفاصل لدنة ویبقى اتصالھا بعید عن محورعقدة العامود ومنطقة
ل المفصل اللدن كما في الشكلتشك
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beams must be considered.
نوصل العناصر القطریة والمائلة في اماكن ونقاط بعیدة عن تشكل المفصل اللد
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Reinforced Concrete Core With steel surrounding
األبنیة ذات الكور الخرساني واالطارات الفوالذیة والمركبة
Core walls enclosing building services such as elevators, mechanical and
electric rooms, and stairs have been used extensively to resist lateral
loads in tall concrete buildings. The use of simple shapes such as C and I shaped walls around elevators
interconnected with coupling beams constitutes one of the most typical
methods of providing resistance to lateral loads. In the composite version of this system, a central concrete shear wall core is
designed to resist the entire lateral load while the remainder of framing
surrounding the core is designed for gravity loads using structural steel, metal
deck and concrete topping (see Figure 2.18) concrete core is built first, using jump or slip forms, followed by erection
of steel surround, as shown in Figure 2.19. Although structural steel erection may not proceed as fast as in
a conventional steel building, the overall construction time is likely to be
less because the building’s vertical transportation, consisting of stairs and
elevators and mechanical and electrical services can
be installed with in the core while erection of steel outside of the core is
still in progress The only nonstandard connection is between shear walls
and floor beams.
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Various techniques have been developed for this connection, chief among
them, are the embedded plate and pocket details, as shown in Figure 2.20.
The floor construction invariably consists
of composite metal deck with concrete topping
The floor within the core may be constructed either in concrete or structural
steel. The connection between the floor slab and core walls is often project specific. او بروفیل فوالذي یمكن للكور ان یكون جدران خرسانة مسلحة
The weld plate detail shown in Figure 2.20a is, however, the most popular,
particularly in a slip-formed construction.
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The weld plates are set with the outer surface flush with the wall surface.
The plate is anchored to the wall by shear connectors welded to the plate. انصال الكمرات الفوالذیة مع جدران خرسانة مسلحة
تة مع براغي في الحجرلنببواسطة صفائح قوالدیة مث
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shear Wall-Frame interactinG systems This system has applications in buildings that do not have sufficiently large
cores to resist the entire lateral loads. This may require interaction of shear walls with moment frames to
supplement the lateral stiffness of the shear cor ا القصیةجملة النظام التفاعلي بیت االطارات والجدران
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Composite tube systems
جملة االطارات االنبوبیة
The key to the success of tube construction as noted earlier, lies in the
rigidity of closely spaced exterior composite columns and deep spandrels. This
results in an exterior façade that behaves more like a bearing wall than as a moment
frame.
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VertiCally mixed systems
ةالمختلط الفصیة لجملا
Mixed-use buildings are thos
e that provide for two or more types of occupancies in a single building.
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For example, lower levels of the building may be for parking; middle
levels for office floors; and the top levels for residential units, such as
apartments and hotel rooms.
Therefore, it makes economical sense to stack up different systems
vertically up the building height using a system that
is most logical for the particular occupancy.
For example, beamless flat ceilings with a minimum
of floor-to-floor height are preferred in residential occupancies
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كور جدران خرسانة طوابق سفلیىة
كور جدران ستیل فوالذیة اعلى
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meGa Frames With super Columns مقاومة القوى األفقیة والشاقولیةالعامود المركب العمالق الكبیر
واحزمة محیطیةیجوائز شبكیة
One of the methods resisting lateral loads in tall buildings to provide big
columns placed as far as possible at the perimeter of building, and
interconnect the columns with a shear-resisting system such as Vierendeel
frames, or super diagonals.
The construction of super columns can take on many forms system uses
large-diameter steel pipes filled with high-strength concrete.
Generally, neither longitudinal nor transverse reinforcement is used in the
columns,.
Another method to encase steel columns using conventional forming
techniques.
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تفاصیل اتصال جائز مركب مع عامود فوالذي
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(A) Plastic stress distribution for negative moment: (a) composite beam section; (b)
plastic neutral axis, PNA, in steel beam web; (c) PNA in beam flange. (B) Plastic stress
distribution for positive moment:
(a) plastic neutral axis, PNA, in concrete slab; (b) PNA in steel beam flange; (c) PNA in
steel beam web.
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AISC Design encased composIte columns
Limitations الكود األمریكي وتصمیم األعمدة المركبة
To qualify as an encased composite column, the following limitations
shall be met:
1. The cross-sectional area of the steel core shall comprise at least 1% of
the total composite
cross section.
2. Concrete encasement of the steel core shall be reinforced with
continuous longitudinal
bars and lateral ties or spirals.
3.The minimum transverse reinforcement shall be at least
0.009 in.2 per in. of tie spacing
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المركبة الفوالذیة و الكود األوربي وتصمیم المباني
TYPES OF CROSS-SECTION FOR COMPOSITE COLUMNS AND THEIR ADVANTAGES
Figure 1 shows typical cross-sections of composite columns together with the dimensional notation used in Eurocode 4 [1]. The sections can be classified into two groups:
concrete filled sections in which the concrete is hidden totally and partly encased sections.
Eurocode 8 rules on steel & composite structures
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Establishing Earthquake Loads for Composite
Shear Walls Using US Codes
حسباب معادلة حمولة الزالزل من الحموالت
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حساب قوة الزالزل من اجل جدران قصیة مركبة
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زیادة المقاومة R جدول استعمال عامل المطاوعة
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جھاد حد المرونة المسموحا
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Design of Composite Wall Element
الدعمة والقص المسموح تواجد
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اشتراط الكود حول جدار القص المركب
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تصمیم القص القاعدي وعزم االنقالب
118
والعامود انصال الصفیحة المعدنیة مع الكمرة
119
تصمیم االطار من الكمرة والعامود
120
االجھدات المسموحة وتحنیب الجسد والجناح
121
الحاسب برنامجمذجة الجدار القصي المركب في ن
122