31 Aug Seismic characteristics of reinforced concrete buildings
Reinforced concrete structures are a less perfect solution in areas with high seismic activity. However, major earthquakes over the past two decades have not revealed any surprises for reinforced concrete structures. It would seem that the main vulnerabilities have already been identified. We’ll look at the reasons
vulnerabilities that we have observed in the field and in the laboratory, and we are able to avoid them
with the right design. Let us consider some basic concepts in the field of reinforced
It is important for the engineer to understand how the structure will respond to strong vibrations, it is the engineer’s responsibility to meet the code of practice.
The response of reinforced concrete structures to strong vibrations can be controlled using
a reasonable balance of three indicators:
one. Ratio of mass to stiffness
2. Weight to strength ratio
3. The ratio of the lateral height offset
Reinforced concrete structures
These ratios are not amenable to precise definitions. Designing earthquake-resistant reinforced concrete structures is closer to art than science.
Consider structures as if they were mounted on their bases and as if they existed in only one vertical plane. Our notional 2D structure sits on the hard ground and is an approximation of the actual structure.
The most convenient definition of the ratio of mass to stiffness of the translational period of vibration of a conditional structure corresponds to the lowest natural frequency. We will be called this amount whenever we describe the “period” if it is not stipulated that it belongs to a higher regime. For preliminary
dosing, the period is the most important characteristic of the structure.
The ratio of weight gain to force
The ratio of weight to force is usually expressed in terms of the “base shear strength” of the structure,
maximum shear strength of the base, obtained by an arbitrary distribution of lateral forces acting on the floor of the levels. The ratio of weight inflow to force (“basic shear strength”) is a rough estimate of how strong a structural system is in relation to load inflow.
This is not an important property of the structure as long as it is above the threshold value.
The third relation is more properly called “power drift” or “marginal drift” of the ratio. This is a measure of the ability of a structure to bend without losing integrity.
For this ground movement, the period and power drift are two important indicators for the correct dosing and detailing the structure. The strength of the base factor shift is hardly important if the engineer has made an unreasonable choice (for example, assigning an entire parking structure to two lateral frame drag forces) or when the peak ground speed is found to be high (More than m/sec).
The seismic resistance of a reinforced concrete structure can only be achieved through the use of appropriate software – as it should be. This material is not intended for detailed design. Rather, it is intended for preliminary design, which can be achieved without
automatic devices, and that the final design produced by the software is reasonable.