A.The Minneapolis Bridge Failure

Name ______Date ______Class ______

Case Study

A.The Minneapolis Bridge Failure

1.The center section of the Interstate-35W (I-35W) in
north Minneapolis, Minnesota, suddenly gave way on August 1, 2007.

2.The failure of the bridge was a surprise because the design and
processes that bridges undergo are supposed to ensure
that bridge failures do not happen.

B.Controlled Experiments

1.In order for investigators to determine why the bridge failed, they needed to use
many parts of .

2.A type of scientific investigation that tests how one factor affects another is called
a(n) .

3.Any factor in an experiment that can have more than one value is called
a(n) .

a.A factor in an experiment that is manipulated or changed by the investigator
is called the .

b.The factor a scientist observes or measures during an experiment
is the

4.All the factors in an experiment that do not change are
called .

5.Data that use words to describe what is observed in an experiment
are called .

6.The part of a controlled experiment used to study relationships among variables
is the .

7.The group that contains the same factors as the experimental group, but the
independent variable does not change, is called the .

Name______Date Class

Lesson Outline continued

D.Truss Bridges

1.A(n) truss bridge is supported only at its two ends, but is strengthened by
an assembly of interconnected triangles, or .

2.The I-35W bridge was a(n) designed in the early 1960s.

a.The beams in the bridge’s deck and the triangular and vertical supports came
together at structures known as .

b.The area where the truss structure connects to the roadway portion of the bridge
gusset plate is called a(n) .

E.Bridge Failure Observations

1.Evaluating why the collapse occurred was difficult because emergency workers
unintentionally the bridge.

2.Investigators eventually recovered the entire structure and placed the various pieces
in their relative original .

3.Investigators found more clues in a(n) from
a motion-activated security camera.

F.Asking Questions

1.Investigators studied various questions to determine why the bridge
or if a combination of factors caused the bridge to fail.

2.A(n) is a force applied to a structure from the structure
itself.

3.Temporary loads to a structure such as traffic, wind gusts, or earthquakes
are called .

4. data uses words to describe what is observed.

5.The use of numbers to describe what is observed is called
data.

6.After thorough modeling and analysis, investigators ruled out the idea that the
bridge failed due to being .

7.Inspection of recovered showed that some of the plates
failed very early in the collapse.

8.Investigators could not determine if undersized plates were used because
of a mistaken calculation, a(n) error, or some other
error in the design process.