KPLAN - 3 of 3 - Q & A - Structural Systems
What happens to a reinforced concrete dome when the exterior temperature rises?
The top of the dome moves up. All structures tend to expand when the temperature increases and contract when the temperature decreases. As the bottom of a dome is prevented by its foundation from expanding and moving outward, the only way the dome can expand is to move upward
Which of the following factors affects the shear capacity of a reinforced concrete beam?
The ultimate 28 day strength of the concrete. If the shear capacity is insufficient to resist the shear force, web reinforcement may be added. The cross sectional area of the longitudinal tension reinforcing is irrelevant in this regard & the beam's load and span affect the shear force on the beam
A 10-foot-deep tank is filled with water. The magnitude of the pressure exerted by the water against the sides of the tank depends on which of the following?
The unit weight of the water and. The depth of the water. Hydrostatic pressure, which is the pressure exerted by a liquid, is equal to the unit weight of the liquid multiplied by the depth of the liquid. The width of the tank that contains the liquid is irrelevant.
Drift caused by earthquake is limited for which of the following reasons?
To insure structural integrity. To minimize discomfort to the building's occupants and. To restrict damage to brittle nonstructural elements. Drift is the displacement of one level of a building relative to the adjacent levels, caused by lateral loads
What is the purpose of belling a caisson?
To increase the caisson's bearing capacity. drilled caisson hears on the soil at its bottom and is constructed by pouring concrete into a drilled shaft. The bottom of the shaft is often enlarged, or belled, in order to increase the hearing area and hence the bearing capacity of the caisson
How do the wind forces used in the design of a fire or police station compare with those used for a standard occupancy structure?
Wind forces are not considered in the design of standard occupancy structures. One of the factors in wind design is the importance factor I, which is equal to 1 for the standard occupancy structures. For hazardous or essential facilities, such as fire or police stations, I increases to 1.15
Which of the following is Not considered to be live load? Wind. Earthquake. Furniture. Snow.
Wind. Earthquake. and Snow. Live load is the load superimposed by the use and occupancy of the building, such as furniture
The wind design regulations in the International Building Code consider all of the following, exposure. gusting. hurricanes. tornadoes.
exposure. gusting. and hurricanes. Only tornadoes are not considered in the IBC wind design provisions.
Pier Luigi Nervi is associated with all of the following design techniques or materials,
ferrocement. concrete lamella roofs. and suspension roofs. He was the first designer to successfully use ferrocement, a combination of steel mesh and cement mortar. His concrete lamella roofs, such as the airplane hangar roofs he built during the 1940s, were among the largest and most elegant roofs
Regarding strength design of reinforced concrete, The ultimate load factors are
greater for live load than for dead load.
The wind pressures at corners, discontinuities and irregularities in the building shape are
higher than those on the wall and roof surfaces.
Seismic forces are generally considered to act
in the 2 horizontal directions parallel to the axes of a bldg, but not at the same time. Structures assigned to SDC A and B and structures assigned to SDC C with no irregularities must be capable of resisting the stresses caused by the seismic forces in each direction, but not at the same time
Steel arches are trussed in order to
increase their bending resistance. For spans longer than 150 feet, steel arches are often trussed to increase their bending resistance
The wind pressures used in the design of buildings in accordance with the IBC
increase with height.
Drift is limited to
insure structural integrity, minimize discomfort, and restrict nonstructural damage. Drift is the lateral deflection of a structure caused by seismic or wind load. The drift of a given story relative to the stories above and below is called story drift.
The wind pressures used in the design of buildings in accordance with the International Building Code are
required to act in both inward and outward directions on wall surfaces.
The result of liquefaction may be
severe settlement of tilting buildings because of the reduced soil bearing capacity, such as occurred in Niigata, Japan, in 1964.
The staggered truss system is usually economical for
spans greater than 45 feet. hotel and residential occupancies.
An earthquake with a magnitude of 8.0 on the Richter scale releases how much more energy than a 4.0 magnitude earthquake? Remember that The scale is logarithmic, with each number representing 10 times the ground motion, or about 33 times the energy of the lower number.
1,000,000 times. The magnitude 8.0 earthquake release 33 times more energy than one of magnitude 7.0, about, 33 squared, more energy than one of magnitude 6.0. about, 33 cubed, more energy than one of magnitude 5.0, and about 33 to the fourth, 1,000,000, more energy than one of magnitude 4.0.
the minimum concrete coverage for reinforcement for footings cast against earth is
3 inches. According to the Building Code Requirements for Reinforced Concrete ACI 3 18, which has been incorporated into many building codes, the minimum concrete coverages are 3" for footings cast against earth.
What is the allowable shear force that can be resisted by a 3/8-inch thick structural I blocked horizontal diaphragm with 8d nails spaced at 6 inches at all panel edges and 3-inch thick framing members at the edges and boundaries?
300 pounds per foot. IBC Table 2306.3.1 is used to determine the allowable shear force for wood structural panel diaphragms for wind or seismic loading. For example, The panel grade is given in the 1st column of the table, the nail or staple size is in the 2nd column,
The additional cost to provide seismic resistance for a building to conform to the IBC regulations for Seismic Design Category D would he roughly what percentage of the total cost of construction?
5 percent or less. With the meager amount of information given in this question, we can only make a rough approximation.
Trusses are generally economical for spans between
60 and 200 feet.
Which type of arch is statically determinate when subject to a uniformly distributed load across the entire span? A two-hinged arch. A three-hinged arch. A fixed arch. Any arch.
A three-hinged arch. A three-hinged arch is the only type of arch that is statically determinate, no matter what the loading is.
Select the correct statement about earthquake design.
Adjacent buildings should be adequately separated to minimize the possibility of pounding.
Which of the following statements about Allowable Stress Design and Load and Resistance Factor Design are correct?
Allowable Stress Design uses unfactored working loads and a single factor of safety. The traditional method for structural steel design is Allowable Stress Design, in which the actual dead and live loads are unfactored, that is, not increased.
Nonstructural building components and the attachments of permanent equipment must be properly designed to resist seismic forces. In this regard, which of the following may be used to resist seismic forces?
Anchor bolts and Bracing. They may be used to resist seismic forces. However, because of possible vertical seismic accelerations and other reasons, friction resulting from gravity loads may not be used to resist seismic forces.
Steel decking and a concrete slab, which act together to span between beams, is called a
Composite deck. A composite deck is steel decking manufactured with deformations that mechanically bond the deck to the concrete slab above it, so that the deck and slab act together as a single structural element to span between floor beams. Composite beams are often confused with composite decks.
Which of the following statements concerning the economy of structural steel framing is correct?
Composite steel deck should be used, rather than non-composite steel deck.
The shape that a cable assumes when the only load acting on it is its own weight is called a
Catenary. If the only load acting on a cable is its own weight, the shape the cable assumes is a catenary. If the loads were uniformly distributed horizontally across the span, the cable would assume the shape of a parabola.
For a simply supported glued laminated beam subject to vertical loads, where is the bending stress maximum?
At the outermost laminations near midspan. Within the depth of the beam, the bending stress is maximum at the outer fibers and minimum at the neutral axis
All of the following are tubular steel buildings,
Bank of China Tower in Hong Kong. Sears Tower in Chicago. John Hancock Building in Chicago. The Sears Tower in Chicago consists of nine tubes that end at varying heights. The John Hancock Building in Chicago and the Bank of China Tower are both gigantic trussed tubes.
Select the correct statement about design for lateral forces.
Buildings assigned to SDC D and higher are designed for wind or earthquake forces, but not both acting at the same time.
Which of the following systems is used by the John Hancock Center in Chicago to resist wind load?
Diagonal bracing. The John Hancock Center's huge diagonal bracing was designed to resist wind loads and is visible on the exterior of the building. This makes the building one of the most recognizable landmarks in Chicago.
What is limited to insure structural integrity, minimize discomfort, and limit nonstructural damage?
Drift. It is the lateral deflection of a structure caused by seismic or wind loads. Although it is not possible to design a building to have zero drift, the amount of drift is limited in order to insure structural integrity, and restrict damage to brittle nonstructural elements
You are the architect for a gymnasium that is 120 feet by 120 feet in plan and has no interior columns. Two systems are being considered: a space frame and a system of one-way parallel trusses spaced 30 feet apart. Which of the following are advantages of the space frame over the parallel trusses?
Economy thru the use of many identical members and connections. Greater stiffness. Less depth. A space frame is a series of trusses that intersect in a grid pattern & are connected at their points of intersection. space frames are statically indeterminate and their structural analysis is complex
Which of the following structures has a form that best reflects the structural concepts of wind resistance? Empire State Building. Eiffel Tower. Stonehenge. or Chrysler Building.
Eiffel Tower. It has a tapered profile, which reduces the wind load as the height increases ,reducing the overturning moment, and provides greater stability because its legs are spread ,increasing the dead load resisting moment. Thus, its form clearly reflects the concepts of wind resistance.
The location on the earth's surface directly above the point where an earthquake fault slippage begins is called the
Epicenter. The location in the earth's crust where slippage begins is called the focus or hypocenter, and its projection on the ground surface is the epicenter
Which of the following statements are correct concerning an air-supported fabric structure that encloses an occupied space?
Fans are required to pressurize the space. People and equipment must pass through airlocks or special doors to get into and out of the facility. Long spans require steel cable reinforcement. Loss of pressure can cause the roof to deflate and possibly fail.
The work of Pier Luigi Nervi is associated with which of the following?
Ferrocelnent. Prefabricated concrete domes. Prefabricated concrete lamella roofs. Suspension bridge roof. Pier Luigi Nervi designed buildings that expressed their structure in bold and imaginative ways. His work is associated with all four structural concepts previously mentioned.
A long period is associated with which of the following?
Flexibility & Low seismic forces Every bldg has a natural or fundamental period of vibration. It is the time in seconds that it takes for the bldg to go through 1 complete back & forth motion when a horizontal load acts on it. A bldg with a long period is flexible & has relatively low seismic forces
Which of the following 19th-century buildings is considered to be the first true skyscraper?
Home Insurance Building. it was Jenney's Home Insurance Building that is considered the first iron and steel framed skyscraper. Although only ten stories high, it was the predecessor of all the tall metal-framed buildings that followed.
I-shaped wood joists consist of lumber flanges and a strand board web inserted and glued into a groove in each flange. What type of stress does the glue resist?
Horizontal shear. As with any I-shaped member, such as a steel plate girder, the flanges substantially resist the flexural tension and compression, the web resists the shear, and the connections between the flanges and the web resist horizontal shear
Which of the following statements concerning the earthquake design of buildings is true?
In an earthquake, the ground moves horizontally and vertically, but the effects of the vertical motion are usually neglected in the design.
Which of the following systems provides maximum flexibility for a hospital without interruption of service?
Interstitial trusses. trusses about 8 ft in depth offer unusual layout flexibility by providing a walk-through ceiling space above each column-free hospital floor. This interstitial space is utilized for all mechanical and electrical services, which can be maintained or changed without interruption
Wind pressures are usually assumed to act in which of the following directions?
Inward on windward walls. Outward on leeward walls. the wind causes a direct, inward pressure as it is stopped by the windward side of the building. And the wind acts outward on the leeward side, creating negative pressure or suction.
Select the correct statements about the Leaning Tower of Pisa.
It began to tilt during construction. The leaning was caused by differential settlement of the underlying soil. The tilting began during the tower's construction and continues to this day; its top is now out of plumb by 16 feet. The tilt of the tower cannot be blamed on its structure
Reduced bearing capacity of loose, saturated sand as a result of earthquake ground motion is known as
Liquefaction, The shear strength of some soils, particularly loose, saturated sands, can be substantially reduced by liquefaction, the soil's tendency to flow like a liquid, caused by earthquake ground motion.
The calculated deflection of a single reinforced concrete beam is excessive, making it necessary to redesign the beam. Assuming no other structural elements are affected, and the load supported cannot be reduced, what is the most efficient way to reduce the beam's calculated deflection?
Make the beam deeper. There are a number of ways to reduce the deflection of beam. The moment of inertia I of the beam may be increased by making the beam wider or deeper, the modulus of elasticity E of the concrete may be increased by using higher strength concrete, or additional reinforcing steel
A parabolic arch supports a uniformly distributed vertical load. What is the nature of the stress in the arch at any point along its length?
Pure compression, no bending moment. If a parabolic arch supports a uniformly distributed vertical load, it will be stressed only in compression, with no bending. Under any other loading, it will be subject to some bending moment.
The soil boring log for a level building site shows that the top six feet of subsurface material consists of a loose fill, below which is a thick layer of dense sand. Which of the following foundation systems could be used on this site?
Mat foundation. Pile foundation. Shallow footings placed after removal & recompaction of the fill. Footings extending through the fill into the dense sand. In this case, as the upper soils consist of loose fill, these loose soils must be removed & recompacted, if they are to support building loads.
What property is practically constant for all structural steels?
Modulus of elasticity. All steel, regardless of strength or other properties, has the same value of modulus of elasticity E, about 29,000,000 psi. Other properties such as yield point, ultimate strength, and weldability will vary depending on the type of steel.
The radius of gyration r of a steel section is a function of which items?
Moment of inertia of the section & Cross sectional area of the section. Remember the radius of gyration, r, of the column section formula is r = the square root of I over A. I is the moment of inertia of the column section and A is the cross sectional area of the column section
Wherever a hinge or pin exists in a structure, there can be no
Moment. A hinge or pin is free to rotate and therefore has no resistance to moment. Actual hinges or pins are rarely used in modern construction. However, a joint that has little moment resistance or restraint against rotation is generally considered to he a hinge or pin.
A building assigned to SDC E has a special steel moment-resisting frame capable of resisting the total required lateral force. Its total dead weight is 15,000 kips. Its fundamental period of vibration is 0.4 seconds. What is the maximum allowable height of the building?
No Limit. Because the building has a special steel moment-resisting frame, its height is not limited by the code
What is the maximum allowable height for a building assigned to SDC D?
No limit. The height limits for a building assigned to SDC D are tabulated in ASCE 7-05 and vary from 35 feet to no limit, depending on the lateral load resisting system used for the building. The maximum allowable height is therefore unlimited.
When seismic forces cause a building to deflect laterally, the vertical load acting on a deflected column results in increased moments. This effect is called
P Delta effect. In seismic events stories deflect horizontally relative to each other. This story to story horizontal movement is called the story drift. If the story drift is delta & the vertical load in a column is P, then the bending moments in the story are increased by P times Delta, or P delta
Open-front buildings are subject to high torsional stresses under earthquake loading. Which of the following are solutions to this problem?
Provide a shear wall at the front, whose stiffness approaches that of the rear shear wall. Use moment-resisting frames of approximately equal stiffness for both front and rear walls
Which of the following are advantages of the stub girder framing system?
Reduced weight of steel. Reduced story height. Simplified steel erection. Ease of providing simulated continuity for floor beams. In the stub girder system, steel floor beams sit on top of a stub girder, instead of framing into a girder.
A steel or concrete frame that has bases fixed against rotation is called a
Rigid frame. A rigid frame is a frame with rigid joints capable of resisting moment. In contrast, a frame with diagonal braces is a braced frame
Which of the following soils may be used to support building foundations?
Sandy gravel. Silty sand. Sandy clay. rock is the best bearing material, followed by sands and gravels. Fine grained soils, such as silts & clays, are adequate to support building foundations, but may require investigation. However organic soils such as peat are unacceptable for the support of bldgs
Wind load resistance for which building is provided by a bundle of nine tubes?
Sears Tower. the entire structure acts like an immense, hollow, tubular column that cantilevers from its foundation under the action of wind loads. The Sears Tower in Chicago consists of nine tubes, each 75 feet square, placed next to each other to form a pattern of three squares in each direction.
A thin shell structure is able to resist which of the following?
Shear, Tension and Compression. A thin shell is a structure with a curved surface that supports load by compression, shear, and tension in its own plane, but is too thin to resist any bending stresses
A two-way truss system in which the trusses are inclined, rather than in a vertical plane is called a
Space frame
The wind pressure on a building is dependent on which of the following factors?
Surrounding terrain. The building's proximity to large bodies of water. The size & shape of the building. The height of the building. friction between the wind & the found causes wind velocity & thus the pressure, to decrease close to the ground & conversely, to increase as the height increases.
Complete the following statement. A cable supports load by
Tension. A cable is essentially the reverse of an arch: an arch is stressed principally in compression, while a cable is stressed in tension. But where arches almost always have some bending moment combined with compression, cables are too flexible to have any significant resistance to bending.
What is meant by redundancy in connection with seismic design?
The ability of a structure to redistribute seismic loads to other elements, if a particular element fails or is damaged. This is called redundancy and can be provided in various ways, including the use of multiple lines of resistance rather than a single line
In earthquake-prone areas, adjacent buildings, or portions of a building, are often separated by a seismic joint. Which of the following statements about seismic joints is correct?
The amount of separation should be at least equal to the sum of the drifts of the two adjacent buildings or portions.
According to the International Building Code, the magnitude of the design wind pressures on a building is influenced by which 4 things?
The building's occupancy category. The height of the building. The exposure of the building. The wind speed.
For a shear wall consisting of wood studs with plywood sheathing, which of the following statements is most correct?
The minimum width of the shear wall is determined by its height. Table 2305.3.4 of the International Building Code specifies the maximum height-to-width ratios for plywood shear walls. For a shear wall of a given height, the minimum width is determined by these ratios.
A system that consists of story-high trusses spanning transversely between exterior columns and arranged in a staggered pattern is called?
The staggered truss system. It is often an efficient and economical structural system for highrise apartment buildings.
Comparing the fundamental period of vibration of a building with that of the ground shaking because of an earthquake, which of the following is most desirable?
The period of the bldg is very different from that of the ground shaking. When the period of a bldg coincides with the shaking ground, the bldg is said to be in resonance with the shaking ground. This greatly amplify the seismic forces & deformations & can lead to severe damage
Describes ductility?
The resilience of a structural system. The ability of a structural system to accommodate seismic loads by inelastic yielding, without collapse.
How do the seismic forces used in the design of a fire or police station compare with those used for a standard occupancy structure?
The seismic forces are greater. One of the factors in seismic design is the importance of factor I, which his equal to 1.0 for the standard occupancy structures. For essential facilities such as fire or police stations, I increases to 1.5 for seismic design.
Which of the following statements about moment-resisting frames are correct?
They are generally more ductile than other systems. They absorb seismic energy by deformation. They are generally designed for smaller seismic loads than other systems. Since they absorb energy by inelastic deformation, they tend to deflect more, than other systems.
Why are stirrups used in reinforced concrete construction?
To provide web reinforcement where the concrete is overstressed in shear. Stirrups are small U-shaped bars, such as #3 or #4, which are placed vertically in a reinforced concrete beam to reinforce the web where the shear stresses are excessive
Why are drop panels and column capitals used in flat slab construction?
To reduce shear stress in the slab near the columns. To provide greater effective depth for negative bending moment. Both drop panels and column capitals are used to reduce shear stress in the slab near the columns and to provide greater effective depth for negative bending moment.
Which of the following are intended purposes of seismic isolation?
To reduce story drift and To reduce a building's acceleration from earthquake ground motion. In seismic isolation, the structure is isolated from the ground by specially-designed bearings and dampers that absorb earthquake forces,
About how much does the cost of construction increase if seismic resistance is provided in the design of a building?
Under 5 percent. Providing seismic resistance may add 5 to 20 percent to the structural cost of a building, or 1.25 to 5 percent to the total construction cost, because the structure usually represents about 25 percent of the total cost of construction.
Which of the following are advantages of Vierendeel trusses?
Unencumbered webs and Simple joints. A Vierendeel truss has no diagonals. Therefore, the web is unencumbered and the joints have a simple appearance. However, Vierendeel trusses tend to have high deflection. A Vierendeel truss requires much more material than a triangulated truss
In existing buildings, which of the following are most vulnerable to damage or collapse as a result of an earthquake?
Unreinforced masonry walls. Retrofitting older buildings to improve their seismic performance has become a major concern to architects in earthquake-prone areas. As with new buildings, the primary objective is to provide for life safety by minimizing the likelihood of collapse.
In general, which of the following will help reduce the cost of structural steel framing?
Use rolled sections rather than built-up sections. and Restrict the number of members to a practical minimum. moment connections are more expensive than nonmoment or simple connections. Highstrength steel has a higher unit cost than conventional A992 steel
A two-story warehouse has 40-foot by 40-foot bays. Which of the following reinforced concrete systems is likely to be the most economical?
Waffle slab. The flat slab system is economical for heavy loads, but not when the spans are much longer than 25 feet. The waffle slab system is appropriate for heavy loads, square bays, and spans up to about 40 feet.
Complete the following statement. An arch supports load by
a combination of compression and bending. An arch is primarily a compression member. In fact, under a given loading, it may be stressed purely in compression. Any other loading will result in some bending, in addition to compression.
A steel beam-and-girder system in which floor beams pass over the main girders and stub girders are welded over the main girders along the same axis is called?
a stub girder system
The flat slab floor system is
a two way reinforced concrete system that is supported directly on the columns, generally without any beams or girders.
The wind pressures used in the design of buildings in accordance with the IBC
account for the effects of hurricanes.
The wind pressures used in the design of buildings in accordance with the IBC
are greater for buildings on flat, open terrain than on terrain with buildings or surface irregularities close to the site.
Unbraced parapet walls must he designed to resist seismic forces that
are greater than the forces used for the bldg's design. the seismic forces that must be resisted by a given element are greater than those used for the design of the bldg as a whole. That's because the individual elements usually lack the redundancy & ductility that the structure as a whole has.
Regarding strength design of reinforced concrete, The reinforcing steel is generally
assumed to resist all the tensile stresses, while the concrete is assumed to resist all the compressive stresses.
A soft first story, that is, one whose stiffness is considerably less than that of other stories, should generally be
avoided if possible, because it can result in severe distortion and stress concentration in an earthquake
The structural system that does not have a complete vertical load carrying frame; gravity loads are supported by hearing walls or bracing systems and lateral loads are resisted by shear walls or braced frames is called a
bearing wall system
Section modulus is a measure of a beam's
bending strength. The section modulus, S=I over c. It is = to the moment of inertia of the beam divided by the distance from the outermost fiber of the beam to the neutral axis. The maximum bending stress f=M over S, so the greater the section modulus, the lower the bending stress for a given moment
In earthquake design wood stud walls should be
bolted to the foundation to prevent the structure from sliding off in an earthquake.
Tubular sections steel columns have less tendency to
buckle than wide flange sections.
There are four basic types of structural systems used in seismic design. A structural system that has an essentially complete frame that supports gravity loads and shear walls or braced frames that resist lateral seismic loads is called a
building frame system.
In composite design The concrete slab resists
compressive bending stresses. In composite design, a steel beam and the concrete slab above it are connected so that they act together as a single structural unit to resist bending stresses. The concrete slab becomes part of the top flange and resists compressive bending stresses
Building structures must be designed to resist
dead load plus live load. Dead load is the vertical load due to the weight of all permanent structural and nonstructural components of a building. Live load is the vertical load caused by the use and occupancy of a building, not including wind, earthquake, or dead loads.
Although trusses are efficient in supporting loads, they are
deep and slender and therefore require adequate lateral bracing.
The section modulus of a beam is equal to its moment of inertia
divided by the distance from the neutral axis to the outermost fiber. The section modulus of a beam which is expressed in inches cube, is equal to the moment of inertia divided by the distance from the neutral axis to the outermost fiber. Thus, S = I over c.
A structural system that has an essentially complete frame that supports gravity loads and a combination of shear walls or braced frames plus moment resisting frames which resist lateral loads is called a
dual system.
The overturning moment is considered in
earthquake design,
The flat slab system is usually
economical for heavy loads, as in warehouses.
A series of parallel arches, skewed with respect to the axes of a building, which intersect another series of skewed arches is called a
lamella roof
Prestressed concrete has greater
material and labor costs than conventional reinforced concrete.
A structural system that has an essentially complete frame supporting gravity loads and moment-resisting frames that resist lateral loads is called a
moment-resisting frame system
Failure due to crushing of the concrete is sudden and without warning. while failure due to yielding of the tensile steel is
more gradual and gives adequate warning of approaching collapse. In order to ensure that failure due to yielding of the steel takes place before failure of the concrete, the code sets an upper limit on the reinforcement ratio by limiting the strain in the reinforcement closest to the tension face
Wide flange shapes are economical flexural members because
most of the beam's material is in the flanges. In a beam, the material close to the outermost fibers is highly stressed in flexure, while the material close to the neutral axis is understressed.
The flat slabs are relatively thin and are therefore
not economical in reinforcing steel.
The acceleration of a building and that of the ground beneath are
not usually the same,
The deflection of a reinforced concrete beam increases
over time, even if the load is not increased.
In historic architecture, the transition from a round dome or drum to the pillars at the comers of a square space below was achieved by
pendentives. One of the features of Byzantine architecture was the dome, which, during the later Renaissance period, was sometimes raised on a drum and surmounted by a lantern. The transition from the round dome or drum to the square base was effected by spherical pendentives
Complete the following statement. A three-hinged arch is
statically determinate. that is, its reactions can be computed using only the basic equations of equilibrium. The supports of a three hinged arch permit rotation, while those of a fixed arch do not. Three-hinged arches are able to resist horizontal loads & can have a variety of profiles
In Mies van der Rohe's Lake Shore Drive Apartments, lateral displacement under wind loads is reduced by the use of
steel plate cladding bonded to the concrete fireproofing. Curtain walls are generally attached to a bldg's frame and are nonstructural. In these bldg, steel plate cladding bonded with studs to the concrete fireproofing, acts not only as a curtain wall, but also provides additional lateral stiffness
When purlins are connected to trusses at the panel points, the top chord members are
subject to axial stress only.
The Richter scale measures
the amount of energy released in an earthquake. The intensity of an earthquake is measured by the Modified Mercalli scale, while the Richter scale measures the amount of energy released in an earthquake. Neither scale measures duration or frequency.
In reinforced concrete construction, compressive reinforcement consists of longitudinal bars placed in
the compressive area of a beam to resist part of the compressive stress. Reinforcement is anchored by mechanical devices andlor embedment, and lateral buckling of compressive reinforcement is prevented by the use of ties
Smaller sizes may be used with prestressed concrete, because
the entire section is effective in resisting applied loads.
In change in the use or occupancy of an existing building, The building must comply with
the live load requirements for the new use.
The greater the height and amount of surface irregularities,
the more interference with the wind and consequently, the lower the wind pressure used in design. Thus the design wind pressures decrease when there are greater surface irregularities
The modulus of elasticity of concrete varies with
the strength and weight of the concrete.
Prestressed concrete members have no tension cracks because
they are completely in compression.
In the staggered truss system, storyhigh trusses spanning the full width of the building are arranged in a staggered pattern:
trusses in the odd-numbered column lines are erected in a given story, while those in the even-numbered column lines are in the stories above and below. Thus, the floor system is supported alternately by the top chord of one truss and the bottom chord of the next.
In earthquake design wood frame buildings usually perform
well in an earthquake and do not pose a significant threat to life, although such buildings and their contents may be damaged.
Wind design depends on the
wind speed. occupancy category. terrain in which the building is located. size and shape of the building. exposure of the building is partially a function of the terrain. Certain essential, hazardous, or assembly buildings are designed for increased wind pressures
A special moment-resisting space frame has the greatest ability to
withstand earthquakes without damage, whereas a shear wall system usually does not perform as well in earthquakes
Two steel angles are to be used for the top chord of a steel truss whose panel points are 10 feet apart. To determine the required size of the angles, the value of the radius of gyration r should be with respect to which axis? X axis or Y axis
x or y, whichever results in the lower value of r. The top chord of a simply supported truss is stressed in compression. As with all steel compression members, the capacity of the truss chord is based on its K, L over r value. K is usually assumed to be 1 and the value of r is the lower value
Regarding strength design of reinforced concrete, The amount of reinforcing steel used ensures that .
yielding of the steel will occur before failure of the concrete
