Serviceability limit states refer to how structures perform under normal loads and consider how structures are used. Serviceability looks at deflections, cracks, vibrations, surface deterioration, and corrosion that don't cause collapse but make structures unfit for use. Periodic inspections of existing buildings should be implemented to identify structural defects, distress, material deterioration, overloading, and unauthorized work to avoid disaster and extend a structure's typical 50-year service life through repairs and maintenance. As-built drawings are important for engineers to properly assess structures.

1. Fellow Constructor S.a.r.l 01/19/2012
Serviceability of a Structure
Serviceability limit states refer to the performance of structures under normal service loads and
are concerned with the uses and/or occupancy of structures. Serviceability is measured by
considering the magnitudes of deflections, cracks, and vibrations of structures as well as by
considering the amounts of surface deterioration of the concrete and corrosion of the
reinforcement. These items will disrupt the use of structures but do not usually involve
collapse; in other words the structure may still be structurally sound but unfit. By complying
with codes and standards, an assumed service life is in
general only of the order of 50 years.
For any given structure, there is a distinct expected
service life which is directly related to environmental
conditions, material properties, as well as repair and
maintenance operations
As shown in the graph, a typical structure’s life cycle
witnesses an optimum performance followed by
deterioration; eventually the system will no longer
function to the expected level, and thus marking the end of its service life. Attempts
for increasing the performance and reducing the degradation (intermediate peaks)
can be attained by conducting repair and maintenance practices.
For this reason, periodic professional structural inspections of existing buildings
should be implemented by the Lebanese government as a precautious act to avoid
disaster. Based on his professional engineering assessment, judgment and advice, the
appointed structural engineer should be visually able to identify:
types of structural defects
signs of structural distress and
deformation
signs of material deterioration
deviation from intended use,
misuse and abuse of the building
which can result in overloading
Any addition or alteration works
which can result in overloading or
adverse effects on the structure.
References available upon request

2. Fellow Constructor S.a.r.l 01/19/2012
In Lebanon, buyers rarely ask for (or keep on the long run) As-Built drawings of their properties.
Unfortunately, people are unaware that expertise asked in future repairs or alterations, in the
absence of on-site detailed information, has a great margin of incertitude.
The availability of the structural layout plan will help the structural engineer to:
Understand the structural system and layout of the building.
Identify critical areas for inspection.
Identify the allowable imposed loads, in order to assess the usage and possibility of
overloading.
Verify if unauthorized addition or alteration works that affect the structure of the
building have been carried out.
There could be some difficulties in the conduct of a visual inspection as some of the main
structural elements may have been covered up by architectural finishes. It is therefore
important that professional judgment be exercised by the structural engineer to determine
which areas to expose for inspection. Reference to structural layout plans to determine the
presence of critical structural elements would be crucial under such circumstances.
In extreme cases, the structural engineer may recommend a full structural investigation rather
than a visual one only. The scope of the full structural investigation includes the following:
Obtaining information relating to the design, construction, maintenance and history of
the building.
Assessing the structural adequacy of the building by checking the structural plans and
calculations and reconstructing the structural plans if they are not available.
Carrying out tests on the materials used and structural elements of the building.
Carrying out load test on parts of the building if necessary.
Recommending appropriate safety precautionary and remedial measures.
Even though predicting the initial service life and the effects of maintenance and rehabilitation
presents a very complex and challenging process, safety, health, and welfare of the public must
always come first.
References available upon request