evil建筑结构英语论文

2021年1月21日发(作者：中国国家主席)
Architecture

Structure

We
have
and
the
architects
must
deal
with
the
spatial
aspect
of
activity,
physical,and
symbolic
needs
in
such
a
way
that
overall
performance
integrity
is
assured. Hence,he or she well wants to think of evolving a building environment as a
total
system
of
interacting
and
space
forming
subsystems.
Is
represents
a
complex
challenge,
and
to
meet
it
the
architect
will
need
a
hierarchic
design
process
that
provides at least three levels of feedback thinking: schematic, preliminary, and final.

Such
a
hierarchy
is
necessary
if
he
or
she
is
to
avoid
being
confused
,
at
conceptual
stages
of
design
thinking
,by
the
myriad
detail
issues
that
can
distract
attention
from
more
basic
considerations .In
fact
,
we
can
say
that
an
architect’s
ability to distinguish the more basic form the more detailed issues is essential to his
success as a designer .
The object of the schematic feed back level is to generate and evaluate overall
site-plan,
activity- interaction,
and
building-configuration
options
.To
do
so
the
architect
must
be
able
to
focus
on
the
interaction
of
the
basic
attributes
of
the
site
context,
the
spatial
organization,
and
the
symbolism
as
determinants
of
physical
means that ,in schematic terms ,the architect may first conceive and model
a building design as
an
organizational
abstraction of essential performance-space in

he
or
she
may
explore
the
overall
space-form
implications
of
the
abstraction.
As
an
actual
building
configuration
option
begins
to
emerge,
it
will
be
modified to include consideration for basic site conditions.
At the schematic stage, it would also be helpful if the designer could visualize
his
or
her
options
for
achieving
overall
structural
integrity
and
consider
the
constructive feasibility and economic of his or her scheme .But this will require that
the
architect
and/or
a
consultant
be
able
to
conceptualize
total-system
structural
options in terms of elemental detail .Such overall thinking can be easily fed back to
improve the space- form scheme.

A
t the preliminary level, the architect’s emphasis will shift to the elaboration of his or
her
more
promising
schematic
design
options .Here
the
architect’s
structural
needs
will shift to approximate design of specific subsystem options. At this stage the total
structural
scheme
is
developed
to
a
middle
level
of
specificity
by
focusing
on
identification
and
design
of
major
subsystems
to
the
extent
that
their
key
geometric,component,
and
interactive
properties
are
established
.Basic
subsystem
interaction and design conflicts can thus be identified and resolved in the context of
total-system
objectives.
Consultants
can
play
a
significant
part
in
this
effort;
these
preliminary-level
decisions
may
also
result
in
feedback
that
calls
for
refinement
or
even major change in schematic concepts.
When the designer and the client are satisfied with the feasibility of a design proposal
at the preliminary level, it means that the basic problems of overall design are solved
and
details
are
not
likely
to
produce
major
change .The
focus
shifts
again
,and
the
design process moves into the final level .At this stage the emphasis will be on the
detailed
development
of
all
subsystem
specifics .
Here
the
role
of
specialists
from
various fields, including structural engineering, is much larger, since all detail of the
preliminary
design
must
be
worked
out.
Decisions
made
at
this
level
may
produce
feedback
into
Level
II
that
will
result
in
changes.
However,
if
Levels
I
and
II
are
handled
with
insight,
the
relationship
between
the
overall
decisions,
made
at
the
schematic and preliminary levels, and the specifics of the final level should be such
that
gross
redesign
is
not
in
question,
Rather,
the
entire
process
should
be
one
of
moving in an evolutionary fashion from creation and refinement (or modification) of
the
more
general
properties
of
a
total-system
design
concept,
to
the
fleshing
out
of
requisite elements and details.
To summarize: At Level I, the architect must first establish, in conceptual terms, the
overall space-form feasibility of basic schematic options. At this stage, collaboration
with specialists can be helpful, but only if in the form of overall thinking. At Level II,
the architect must be able to identify the major subsystem requirements implied by the
scheme and substantial their interactive feasibility by approximating key component
properties .That
is,
the
properties
of
major
subsystems
need
be
worked
out
only
in
sufficient
depth
to
very
the
inherent
compatibility
of
their
basic
form-related
and
behavioral
interaction
.
This
will
mean
a
somewhat
more
specific
form
of
collaboration
with
specialists
then
that
in
level
I .At
level
III
,the
architect
and
the
specific
form
of
collaboration
with
specialists
then
that
providing
for
all
of
the
elemental design specifics required to produce biddable construction documents .
Of course this success comes from the development of the Structural Material.

rced Concrete


Plain concrete is formed from a hardened mixture of cement ,water ,fine aggregate,
coarse aggregate (crushed stone or gravel),air, and often other plastic
mix
is
placed
and
consolidated
in
the
formwork,
then
cured
to
facilitate
the
acceleration of the chemical hydration reaction lf the cement/water mix, resulting in
hardened
concrete.
The
finished
product
has
high
compressive
strength,
and
low
resistance
to
tension,
such
that
its
tensile
strength
is
approximately
one
tenth
lf
its
compressive
strength.
Consequently,
tensile
and
shear
reinforcement
in
the
tensile
regions of sections has to be provided to compensate for the weak tension regions in
the reinforced concrete element.
t
is
this
deviation
in
the
composition
of
a
reinforces
concrete
section
from
the
homogeneity of standard wood or steel sections that requires a modified approach to
the
basic
principles
of
structural
design.
The
two
components
of
the
heterogeneous
reinforced concrete section are to be so arranged and proportioned that optimal use is
made of the materials involved. This is possible because concrete can easily be given
any
desired
shape
by
placing
and
compacting
the
wet
mixture
of
the
constituent
ingredients
are
properly
proportioned,
the
finished
product
becomes
strong,
durable,and,
in
combination
with
the
reinforcing
bars,
adaptable
for
use
as
main
members of any structural system.

The techniques necessary for placing concrete depend on the type of member to be
cast:
that
is,
whether
it
is
a
column,
a
bean,
a
wall,
a
slab,
a
foundation.
a
mass
columns,
or
an
extension
of
previously
placed
and
hardened
concrete.
For
beams,columns, and walls, the forms should be well oiled after cleaning them, and the
reinforcement
should
be
cleared
of
rust
and
other
harmful
materials.
In
foundations,the earth should be compacted and thoroughly moistened to about 6 in. in
depth to avoid absorption of the moisture present in the wet concrete. Concrete should
always
be
placed
in
horizontal
layers
which
are
compacted
by
means
of
high
frequency power-driven vibrators of either the immersion or external type, as the case
requires, unless it is placed by pumping. It must be kept in mind, however, that over
vibration
can
be
harmful
since
it
could
cause
segregation
of
the
aggregate
and
bleeding of the concrete.
Hydration of the cement takes place in the presence of moisture at temperatures above
50°
F. It is necessary to maintain such a condition in order that the chemical hydration
reaction can take place. If drying is too rapid, surface cracking takes would
result in reduction of concrete strength due to cracking as well as the failure to attain
full chemical hydration.
It is clear that a large number of parameters have to be dealt with in proportioning a
reinforced concrete element, such as geometrical width, depth, area of reinforcement,
steel strain, concrete strain, steel stress, and so on. Consequently, trial and adjustment
is necessary in the choice of concrete sections, with assumptions based on conditions
at
site,
availability
of
the
constituent
materials,
particular
demands
of
the
owners,
architectural
and
headroom
requirements,
the
applicable
codes,
and
environmental
reinforced concrete is often a site- constructed composite, in contrast to the standard
mill-fabricated beam and column sections in steel structures.A trial section has to be
chosen for each critical location in a structural system.
The trial section has to be analyzed to
determine if its nominal
resisting strength
is
adequate
to
carry
the
applied
factored
load.
Since
more
than
one
trial
is
often
necessary to arrive at the required section, the first design input step generates into a
series of trial-and- adjustment analyses.

The trial-and
–
adjustment procedures for the choice of a concrete section lead to the
convergence
of
analysis
and
design.
Hence
every
design
is
an
analysis
once
a
trial
section is chosen. The availability of handbooks, charts, and personal computers and
programs
supports
this
approach
as
a
more
efficient,
compact,
and
speedy
instructional method compared with the traditional approach of treating the analysis
of reinforced concrete separately from pure design.
ork

Because earthmoving methods and costs change more quickly than those in any other
branch of civil engineering, this is
a field where there are real opportunities for the
enthusiast. In 1935 most of the methods now in use for carrying and excavating earth
with rubber-tyred equipment did not exist. Most earth was moved by narrow rail track,
now relatively rare, and the main methods of excavation, with face shovel,backacter,
or
dragline
or
grab,
though
they
are
still
widely
used
are
only
a
few
of
the
many
current
methods.
To
keep
his
knowledge
of
earthmoving
equipment
up
to
date
an
engineer
must
therefore
spend
tine
studying
modern
machines.
Generally
the
only
reliable up-to- date information on excavators, loaders and transport is obtainable from
the makers.
Earthworks or earthmoving means cutting into ground where its surface is
too
high
( cuts ), and dumping the earth in other places where the surface is too low ( fills).To
reduce earthwork costs, the volume of the fills should be equal to the volume of the
cuts and wherever possible the cuts should be placed near to fills of equal volume so
as to reduce transport and double handling of the fill. This work of earthwork design
falls on the engineer who lays out the road since it is the layout of the earthwork more
than
anything
else
which
decides
its
cheapness.
From
the
available
maps
ahd
levels,the engineering must try to reach as many decisions as possible in the drawing
office
by
drawing
cross
sections
of
the
earthwork.
On
the
site
when
further
information becomes available he can make changes in his sections and layout,but the
drawing office work will not have been lost. It will have helped him to reach the best
solution in the shortest time.
The cheapest way of moving earth is to take it directly out of the cut and drop it as fill
with the same machine. This is not always possible, but when it can be done it is ideal,
being both
quick and cheap. Draglines, bulldozers and face shovels
an do this. The
largest radius is obtained with the dragline,and the largest tonnage of earth is moved
by the bulldozer, though only over short disadvantages of the dragline
are that it must dig below itself, it cannot dig with force into compacted material, it
cannot dig on steep slopes, and its dumping and digging are not accurate.
Face shovels
are between bulldozers and draglines, having a larger
radius of action
than bulldozers but less than draglines. They are able to dig into a vertical cliff face in
a
way
which
would
be
dangerous
tor
a
bulldozer
operator
and
impossible
for
a
dragline. Each piece of equipment should be level of their tracks and for deep digs in
compact material
a backacter is most useful, but its dumping radius is
considerably
less than that of the same escavator fitted with a face shovel.
Rubber- tyred
bowl
scrapers
are
indispensable
for
fairly
level
digging
where
the
distance
of
transport
is
too
much
tor
a
dragline
or
face
shovel.
They
can
dig
the
material deeply ( but only below themselves ) to a fairly flat surface, carry it hundreds
of meters if need be, then drop it and level it roughly during the dumping. For hard
digging it is often found economical to keep a pusher tractor ( wheeled or tracked ) on
the digging site, to
push each scraper as it returns to
dig. As soon as the scraper is
full,the pusher tractor returns to the beginning of the dig to help the nest scraper.
Bowl scrapers are often extremely powerful machines;many makers build scrapers of
8 cubic meters struck capacity, which carry 10 m ?
heaped. The largest self- propelled
scrapers are of 19 m ?
struck capacity ( 25 m ?
heaped )and they are driven by a tractor
engine of 430 horse-powers.
Dumpers
are
probably
the
commonest
rubber-tyred
transport
since
they
can
also
conveniently be used for carrying concrete or other building materials. Dumpers have
the earth container over the front axle on large rubber-tyred wheels, and the container
tips forwards on most types, though in articulated dumpers the direction of tip can be
widely varied. The smallest dumpers have a capacity of about 0.5 m ?
, and the largest
standard types are of about 4.5 m ?
. Special types include the self-loading dumper of
up to 4 m ?
and the articulated type of about 0.5 m ?
. The distinction between dumpers
and
dump
trucks
must
be
remembered .dumpers
tip
forwards
and
the
driver
sits
behind
the
load.
Dump
trucks
are
heavy,
strengthened
tipping
lorries,
the
driver
travels in front lf the load and the load is dumped behind him, so they are sometimes
called rear-dump trucks.