Keseimbangan statis tertentu pada konstruksi bangunan bertingkat
Approximate Lateral Deflections of Vertical Elements
2a
FIGURE 7-19
DEFLECTION OF A RIGiD FRAME SUBSYSTEM DERIVES FROM OVERALL
SHEAR AND MOMENT-RESISTING ACTION IN COLUMNS.
HAsH
SHEAR EFFECT
(RACKING)
MOMENT EFFECT
(OVERALL BENDING)
OVERALL EFFECT
(RACKING + BENDING)
H~H
H L~ ~
building is some 40 stories or higher. For a rigid frame, lateral deflection
(also termed side-sway) may result from unsymmetrical vertical loading on
the beam. For example, the frame in Figure 7-20 will deflect as shown.
Such unsymmetrical loadings on various floors of a multistory frame will
tend to balance themselves, and the side-sway so produced is usually
neglected.
Trussed walls do not rely on rotational stiffness of frame joints and are
more efficient than rigid frames in providing stiffness, because each
member is uniformly and more fully stressed. Their deflections are also
simpler to estimate, as shown in Case 5.
The Case 1-5 formulas can be useful, but the reader should understand
that they are grossly simplified. They should only be used for the purpose of
getting a very rough idea as to the relative stiffness of various subsystems
and for obtaining an approximate measure of the la~eraI deformation of a
building. They can also be very helpful when generating and comparing
FIGURE 7-20
SIDE-SWAY MAY RESULT
FROM UNSYMMETRICAL
LOADINGS.
Approximate Lateral Deflections of Vertical Elements
2a
237
Approximate Lateral Deflections of Vertical Elements
EXAMPLE 7-5
-
FLOOR PLAN
MOMENT
DIA&RAM
01~ (~,
0
0
cI
-J
H 20
TRANSVERSE DEFLECTION.
~CORE SHAFT
TOrAL Ni, 58500 K •f~1~
TRANSVERSE ELEVATION OF CORE
L2’ TYPICAL
F 20’H
TRANSVERSE ELEVATION
OF BUILDING
~20
TOTAL OF 9 COLUMNS © 20’C-C
COLUMN
SECTION
1~
I
I
—)
I— 20” TYPIcAL
~
ALL WAILS
2” THICK
H--20’
I
I
fl/fl fly// ~//?/~/ff~~
__________
1 2d~1
~ /1\I
I
Ii’
~ A’
I
I
I
±
25’i
A
Hi2’H
I
I
GIRDER
SECTION
lateral force-resisting elements are the center concrete shaft (20 ft X 40 ft in
section and made up of four 12-in, walls) and the reinforced-prestressed
concrete frames (made up of 12 in. x 30 in. 1-beams and 20-in.-square
reinforced concrete columns). Compute for WL = 30 psf in the transverse
direction only.
The following simplifying assumptions are made:
1. Columns are of uniform sectional properties and height for all stories.
Approximate Lateral Deflections of Vertical Elements
2. Shaft walls are of uniform thickness for all stories. Neglect wall
openings.
3. (w) is uniform over the height of building.
2a