Inspection and Evaluation of Building Structures - Retrofitting Design of Building Structures - page 26

in static load tests has advantages such as it has a wide range, allows reading and measuring
from a long distance, recording automatically, and directly transmitting the result signal
into the computer to perform the data collecting and processing, all of which make the
measurement convenient.
As for the arrangement of test points, besides those in the areas with the maximum
deflection, test points should also be set at each end (support) of the members to measure the
deformation, and the corresponding errors should be deducted when analyzing the measured
data.
(2) Using level gauge
The method of measuring the deformation of the beams and slabs with a level is as
follows: Set the surveyor's poles vertically at the supports and mid-span of the beams and
slabs, measure the reading on the leveling poles at the same height, and compare the reading
of the support and the mid-span to get the deflection of mid-span of the member. As there
might be some errors in the process of setting the leveling poles and measuring, it is dicult
to achieve a precise deflection value.
(3) Another way to measure the deflection of the mid-span of beams and slabs
Tighten a steel wire or a chord wire between the supports of beams or slabs, then measure
the distance from the wire to the member surface in the mid-span to get the deflection of the
mid-span of the member. Generally speaking, tightening will directly affect the measuring
result; this method will cause a bigger error.

2.4.2 Inclination Inspection of Buildings

The outer corners of the buildings can be considered as the observation points for inclination
inspection. Generally, the inclination inspection should be conducted on all four outer
corners of the building. After a comprehensive analysis, the inclination of the whole building
can be determined. Now, theodolite is the most widely used device for inclination inspection.
(1) Determination of the position of theodolite
The position of theodolite is shown in Fig. 2.12; the distance between the theodolite and
the building ( L ) should be larger than the building height.

D

C

A

B

Fig.2.12 Inclination inspection of buildings.
(The continuous lines in the figure indicate the original building, while the dashed lines indicate the
inclined building.)

(2) Measurement of the inclination
As shown in Fig. 2.13, aim at the point M at the top of the wall corner, cast down to
the point N , measure the horizontal distance A of NN , then take point M as a reference
point, and get the angle α with theodolite.