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This chapter presents an overview of the RSP method and contains detailed information on how to fill out the data collection form. A copy of the form for NEHRP Map Areas 5, 6 and 7 (i.e, the high seismicity portions of the United States) is shown in Figure 4-1a. The form has been designed to be filled out in a smooth progressive manner, with a minimum of writing (most items simply can be circled). A discussion of how structure hazard scores and modifiers of the RSP method were developed is presented in Appendix B of the handbook technical supporting documentation, ATC-21-1. As a guide, a quick reference sheet is shown in Figure 4-1b.

4.1 Overview of the RSP Method

Briefly, the RSP method consists of inspecting a building from the exterior (termed a "sidewalk survey") in order to quickly determine if the building is probably adequate for the earthquake forces it is likely to experience, or whether there may be reasonable doubts as to the building's seismic performance. The result of the rapid visual screening procedure is a finding as to whether the building should or should not be subjected to more detailed investigation as to its seismic adequacy. It should be obvious that no rapid visual examination can provide highly reliable estimates of seismic performance, and the RSP method is simply intended to identify those buildings where reasonable doubts may exist. It should be recognized that the RSP is a simple screening procedure and as such is limited. In some cases the RSP may miss buildings that in reality are seis

mically weak, so that if questions exist in the surveyor's mind regarding a particular building, the surveyor should err on the side of requiring the building to be investigated in further detail.

A basic concept of the RSP is to identify, for the building under review, which of several typical building types it corresponds to. These typical building types as defined for use in this method are listed in Table 4-1.

In many cases, an experienced building inspector or other person knowledgeable in building practices will readily be able to determine which of the categories most accurately describes a particular building. This often involves not only general knowledge of building practices but also familiarity with specific regional patterns such as when a particular building type became popular, or local architectural, climatic and economic influences on building practices.

The twelve building categories are sufficiently broad yet distinguishable so that seismic performance can generally be estimated by experts, based on past experience. Based on this expert opinion, a Basic Structural Hazard score can be assigned to a typical building in each category, depending on the earthquake forces it is likely to experience. This Basic Structural Hazard score reflects the estimated likelihood of a typical building of that category sustaining major damage, given its seismic environment (see ATC-21-1, Appendix B, for details). Major damage means that repairs would cost approximately 60 percent of the building's value (not including land or site improvements). This value of 60 percent was selected because it often results in the building

being a total economic loss and, more importantly, it is about the threshold where lifesafety (i.e., building collapse) begins to become a serious hazard. The Basic Structural Hazard scores are given in Table 4-2.

These Basic Structural Hazard scores range from 1 to 8.5, depending on the structural type and the NEHRP Map Area. The values have been determined so that a seismically good building has a high value, and a potentially weak or hazardous building has a low value. The idea is that a building that requires no further review should "score" high, and if it scores low, it should be considered hazardous, at least until a more thorough review is conducted.

As briefly discussed above (and in more detail below), there are significant factors, such as irregularities in the structural system, deterioration of structural materials, adverse soil conditions, or excessive wall openings, that can negatively affect a building's seismic performance or adequacy. In order to account for these factors, a series of Performance Modification Factors (PMFs) have been determined, which, when subtracted from the Basic Structural Hazard score, result in the final Structural Score S for the building under review.

Thus, the RSP consists of the surveyor visually inspecting the exterior of the building, this inspection documented by sketches and photographs, in order to:

1. identify the basic structural category most appropriate for the building, and the corresponding Basic Structural Hazard score 2. identify on the basis of visual inspection

those significant factors that would modify the seismic performance of the building, and the PMF values corresponding to these factors

3. subtract the PMF values from the Basic Structural Hazard score, to arrive at a final Structural Score S

At the local community's option (depending

on its needs and legal constraints), the inspector may enter the building in order to more closely inspect the structure. A simple look above a suspended ceiling will often reveal the basic structural system, although more than one look may be required for the whole building. Bear in mind, however, that entering the building will substantially increase the time required for inspection and requires obtaining the owner's permission.

As stated previously, the Structural Score S is the basic measure of the degree of adequacy of the building. It can be related to the probability of major damage (as explained in the supporting technical documentation, ATC-21-1, Appendix B). A high Structural Score S is good, and a low S denotes probable poor seismic performance, and that the building should be reviewed in detail by a professional engineer experienced in seismic design. Generally speaking, if a building's Structural Score S is less than about 2, then the seismic performance of that building may not meet modern seismic criteria and the building should be investigated further.

In the remainder of this chapter each element of the RSP data collection form (Figure 4-1a) is reviewed. Detailed information is provided on various factors affecting building seismic performance, and the Structural Score S is discussed. In filling out the form, if certain information is not clearly known and is estimated by the inspector, the lower confidence in this information should be indicated by an asterisk (*) next to that number.

4.2 Building Location and Identification

Space for this is provided in the upper righthand portion of the form. This information may be entered manually, or be printed on a peel-off label. One of the most important items for subsequent use in hazard assessment and mitigation for the community is the identification and location of the building. In its records, a