For a single spectrally matche d ground motion record, the individual modal maxima from LRH analysis will be virtually identical to those obta ined using MRS, but the individual modal responses can be di rectly added instead of using statistical procedures such as the square root of th e sum of the squares (SRSS), or complete quadratic combination (CQC).

Earthquake Spectra Matlab Code Cycles With

This updated procedure differs somewhat from the LRH analysis procedures provided in Chapter 16 of the preceding code cycles with the primary difference being that recorded ground motions are adjusted for use in analysis by spectral matching.

The idea behind this approach is to provide an analysis method that is similar in principle to Modal Response Spectrum (MRS) analysis, but due to direct addition of modal responses, preserves the sign (eg.

To simplify the process of spectrum matching, an interactive computational tool called the Spectrum Match Toolkit was developed using the RSPMatch09 as the analysis engine.

Available at no cost, this Toolkit is capable of simultaneously matching upto 3 pairs of horizontal ground motion components and provides the matched records in a form that is convenient for the subsequent response history analysis.

This paper briefly discusses the new 2015 NEHRP provisions for LRH analysis, provides a summary of the theory behind response spectrum matching, discusses the implementation of the procedure using Matlab, and demonstrates some of the unique features of the Toolkit.

Amplitude Scaled (left); Spectrum Matched (right) Main graphical interface of Spectrum Match Toolkit Target Panel for selecting required target spectrum Output GM Panel for performing spectrum match 1 Output tool for summarizing differences in spectrum match Figures - uploaded by Jeena Rachel Jayamon Author content All figure content in this area was uploaded by Jeena Rachel Jayamon Content may be subject to copyright.

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This updated pr ocedure differs somewhat from the LRH analysis procedures provided in Chapter 16 of the preceding cod e cycles with the primary difference being that recorded ground motions are adjusted for use in analysis by spectral matching.

The idea behind this approach is to p rovide an analysis method that is similar in principle to Modal Response Spectrum (MRS) analysis, but due to direct addition of modal responses, preserves the sign (eg.

To simplify the process of spectrum matching, an intera ctive computational tool called the Spectrum Match Toolkit was developed using the RSPMatch09 as the analysis engine.

Described in detail in Chapter 16 of ASCE 7 (ASCE 2010), LRH requires the development of a mathematical model of the structure, the selection and scaling of an appropriate number of ground motions capable of simulating the expected seismic hazard at the building location, the use of a numerical time ste pping algorithm to compute the responses to ground accelerati ons and the recording and statistical manipulation of computed response parameters at both the local and global levels of the structure.

Though ELF and MRS analysis is widely used in practice, these procedures have certai n limitations when compared to LRH analysis.

ELF does not directly include the effects from higher modes and thus loses accuracy where higher mode effects are import ant.

MRS provides improved multimode analysis, but through the statistical proc edures for combining modal responses loses the sign of displacements and element force results, thus making it cumbersome to implement in design.

The response history analysis appro ach, including both linear and nonlinear models was first introduced in building codes with the 1997 NEHRP provisions and was later introduced into ASCE 7-98.

Since then, every code cycle of ASCE 7 (2002, 2005 and 2010) had issued minor updates for an alysis requirement in terms of ground motion selection and scaling, development of the structur al model and evaluation of acceptance criteria.

It is noted that in each case, both linear and nonlinear procedures were included in Chapter 16 of ASCE 7.

For the 2015 NEHRP Provisions (FEMA 2015), and ultimately for the ASCE 7-16 code cycle, the Building Seismic Sa fety Council (BSSC) led the effort to develop an entirely revised version of Ch apter 16, which is strictly limited to nonlinear response history procedures.

Furt her description and validation of these procedures for Chapter 16 can be found in detail in Haselton et al.

Jarrett et al. (2015) and Zimmerman et al.

A new set of procedures for linear response history analysis was also deve loped for the 2015 NEHRP Provisions as well as ASCE 7-16 and this is placed in Chapter 12.

Thus Chapter 12 of ASCE 7-16 will provide in adjacent sections the ELF procedure (Section 12.8), the MRS method (Section 12.9) and the LRH procedure (Sec tion 12.10).

This new LRH procedure is described in some deta il in Charney (2015).

One of the principal features of the proposed LRH analysis is the requirement to use spectrum matched ground motions, in stead of allowing (indirectly through Commentary language) spectrum matching.

T he spectrum matching is used to provide ground motions with spectra that closely follow the shape of th e response spectrum used with the MRS procedure, thereby providing parity with the MRS method.