ETL 1110-2-534
30 Sep 94
APPENDIX A: STRUCTURAL SAFETY ASSESSMENT
OF EXISTING METAL GUARDRAILS
A-1. Introduction
Ornamental and Miscellaneous Metals Association).
The majority of the information set forth herein was
taken directly from their manuals and adapted for the
a. Concern over the protection of both employ-
analysis of existing railings, instead of the design of
ees and the general public against accidental injuries
new railings. The procedures are basically the same,
has greatly increased in recent years. As a result, the
except, in an analysis, the engineer must be careful to
proper design of protective devices for this purpose
determine actual existing conditions (such as dimen-
has become more crucial. Prominent among such
sions, section sizes, and existing condition) in order
protective devices are railings of all kinds, commonly
to make an accurate safety assessment.
referred to as "guardrails" or "vertical barriers." For
years, railings have been built to resist a certain
(2) In a structural design, the sizes (i.e., section
amount of lateral loading as variously specified by
modulus) of load-carrying members are determined
local building codes and the USACE. However, with
based on the applied loadings, allowable stresses, and
the advent of many recent Federal regulations govern-
member lengths and spacings. In a structural analy-
ing the design of railings, more careful consideration
sis, the dimensions, etc., of the system are already
must be given to the railings' structural design and
known and the applied stresses are compared with the
physical features.
allowable stresses of the members to determine
whether the system is safe. For guardrail systems,
b. Although the differences between railing
the areas of greatest structural concern are bending
design requirements among the building codes are
moments in the rails and posts and anchorage stresses
now becoming fewer, past railing specifications have
at the connection of the posts to the supporting plat-
been widely varied, with some much more stringent
form. Therefore, for the structural analysis of an
than others in regard to structural requirements. As a
existing guardrail system, the following quantities
result, it is possible that some existing guardrails are
must be defined:
structurally inadequate according to the current
USACE specifications. Since numerous USACE
Existing condition of the railing.
projects make extensive use of metal guardrail sys-
tems for protection of life, this possibility must be
Material type and properties, section proper-
given careful attention.
ties, lengths, and spacings of railings and
posts.
c. This ETL provides guidance for the engineer
to use in assessing the structural safety of existing
Required loadings.
metal railing. It is primarily concerned only with the
most basic and most common type of utilitarian rail-
Post anchorage details.
ings, i.e., those constructed with metal pipe or tubing.
Presence of reinforcing inserts at base of
d. The manual EM 385-1-1 prescribes the safety
posts.
and health requirements for all USACE activities and
operations. Section 21.B of the October 1992 edition
(3) The reconnaissance of these items and their
of the manual contains the requirements for standard
application to structural safety analysis are described
guardrails and handrails.
in the following paragraphs.
b.
Existing condition.
A-2. Structural Safety Assessment
(1) Prior to any structural safety assessment, the
a. General.
existing condition of the in-place railing must be
determined. This should be accomplished through
(1) Considerable attention has been given to the
careful onsite inspection of the railing. Check the
design of guardrails by industry associations such as
guardrail members for any signs of internal or exter-
the NAAMM (National Association of Architectural
nal corrosion (which causes reduced cross-section) or
Metal Manufacturers) and NOMMA (National
A-1
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