Civil Engineering Reference
In-Depth Information
M
M
N
N
N
α
A
A
L
L
Fig. 2.13
Measuring method.
(3) Analysis and computation of the inclination data
According to the vertical angle
α
, height can be calculated by the following equation:
H
=
L
·
tg
α
(2
.
4)
Then the inclination of the building will be:
i
=
A/H
(2
.
5)
The inclination of the outer corner is:
(
H
+
H
)
A
=
i
·
(2
.
6)
By repeating steps (2) and (3), the gradients of all four outer corners can be obtained,
which can comprehensively reflect the inclination of the whole building. During rectification
for existing buildings, it is necessary to do the inclination inspection.
2.4.3
Settlement Inspection of Buildings
When doing structural retrofitting design, it is necessary to learn about the settlement
of a building, including the rate of settlement and nonuniform settlement. If the original
information about the settlement is available, the accumulated settlement could be acquired.
For the buildings with unsteady rate of settlement, the superstructure cannot be retrofitted
before the foundation is strengthened.
The settlement inspection is very important for
retrofitting design.
Level is the most widely used device for settlement inspection. Today, the optical sensor
is available, which means the optical sensor technology has been applied to the settlement
inspection. In this section, the method of settlement inspection with a level will be mainly
discussed.
In order to assure the measuring precision, it is suitable to employ the level II. Do not
change the measuring tools or the surveyor during the survey process. In order to obtain
continuous settlement data, do not change the reference point and the elevation arbitrarily,
and calibrate the devices accurately.
(1) Arrangement of reference points
Use the reference points of the existing building to determine the accumulated settlement
after measurement. The principle of arranging the reference points is to ensure the stability.
Two or three exclusive reference points for settlement inspection need to be embedded at the
