Assessment of horizontal seismic coefficient for gravity quay walls by centrifuge tests

Abstract

In the simplified analysis of seismic design of gravity quay walls based on the pseudo-static approach, selection of an appropriate horizontal seismic coefficient (k h ) is important for computing the equivalent pseudo-static inertial force. However, there is no unified standard for defining k h . There are conflicts among the existing k h definitions regarding whether it considers (a) the effect of wall height on maximum horizontal acceleration (MHA) used in the determination of k h or (b) the application of correction factor for k h according to seismic performance grade. This paper evaluates the relevance of these conflicts by initially reviewing the k h definitions in the existing codes and guidelines for port structures and then by performing a series of dynamic centrifuge tests on caisson gravity quay walls of different wall heights (5, 10 and 15 m). A review of the existing codes and guidelines has shown that the correction factor for k h should be specified according to the seismic performance grade for the economical design of quay walls. On the other hand, based on the centrifuge tests, it was found that the MHA used in k h calculation and the correction factor for considering seismic performance grade should reflect the effect of wall height.

Seismic performance of gravity retaining walls

“…The seismic design codes do not consider the effect of the soil‐structure interaction, damping, nonlinear stress‐strain behavior of soil, deformation state and support condition of retaining walls for the assessment of horizontal seismic coefficient. Similar results have been reported by several researchers 28,32,37–41,43,53 $$$$\begin{equation}RMSA = \frac{{{k}_h}}{{PGA/g}} = \frac{1}{r}\end{equation}$$$$where, $${k}_h$$ is horizontal seismic coefficient which is assumed acting centre of the failure surface, g is gravity acceleration, r is a correction factor ranging from 1 to 2 depending on allowable maximum residual or permanent displacement of retaining wall.…”

“…Lee et al. (2017, 2019) 39,43 stated that there was confusion among the designers in the use of traditional pseudo‐static limit equilibrium methods to determine dynamic forces behind of the retaining walls due to the discrepancies in the calculation methods of horizontal seismic coefficients ($${k}_h$$) in seismic design codes or guidelines.…”

“…They reported that limit equilibrium methods recommended by Okabe (1924) 1 and NCHRP (2008) 5 for cohesive backfill materials resulted in underestimated dynamic force values from shaking table test results and gravity retaining wall with cohesive backfill material had higher dynamic earth pressure values than cohesionless backfill material. Lee et al (2017Lee et al ( , 2019 39,43 stated that there was confusion among the designers in the use of traditional pseudo-static limit equilibrium methods to determine dynamic forces behind of the retaining walls due to the discrepancies in the calculation methods of horizontal seismic coefficients (𝑘 ℎ ) in seismic design codes or guidelines.…”

“…The case studies indicate that the seismic behavior of rigid retaining walls are not fully understood. Therefore, the seismic performances of the retaining structures have been investigated with reduced or full scale model tests 2,20–46 and numerically 14,46–53 …”

مطالعه آزمایشگاهی ضریب شتاب لرزه ای مورد استفاده در تحلیل شبه استاتیک دیوارهای خاک مسلح پلیمری در مجاورت ساختگاه های سنگی

“…Q[ Q=Okt R= 'u=mtQ}}eD K]U V}=Ri= =@ 'OwW|t QO |=xRQr ?=DW ?} Q[ QDt=Q=B Q=Okt xm OyO|t u=Wv V}=tR; Q=yJ G}=Dv xU}=kt "CU= sDU}U |=xRQr OQmrta `@=D 'OwOLt R} Qm =N =@ KrUt l=N |=yQ=w}O sDU}U O=a@= w |ovU x=oDN=U xUOvy uwJty |rt=wa x@ xDU@=w R}v |=xRQr OQmrta [31] 'KrUt l=N |=yQ=w}O CN=U QO |@Uv sm = QD Q=Okt uOw@ q=@ x@ xHwD =@ xU=t xO=iDU= OQwt l=N `wv w q=@ sm = QD =@ |m} R}i pOt CN=U |=yC}OwOLt u; x@ u=wD|t =yV}=tR; QO xm |tm = QD u} QDq=@ "OQ=O OwHw xOW |Ov@xv=O O@ xDiQo Q= Qk Q_vOt R}v VywSB u}= QO sm = QD Q=Okt u}= xm CU= OYQO 85 'Ci=}CUO xm CU= xOW xi=[= l=N x@ C@ w]Q OYQO 5 u= R}t 'QDy@ sm = QD Qw_vt x@ "CU= CQwYx@ l=N sm = QD Ov}=Qi "CU= l=N xv}y@ C@ w]Q OL QO C@ w]Q u= R}t u}= |=ypOt CN=U QO "CU= xOW s=Hv= |DUO |=yx@wm R= xO=iDU= =@ w x}q x@ x}q xU=t Cqt x}q xr}Uw x@ |ovU x=oDN=U w R} Qm =N u}@ lQDWt K]U '|m}R}i "CU= xOW |R=Ux}@W u=t}U =yV}=tR; G}=Dv "5 "OwW|t x=Q= CWB R= Q=Wi p=ta= |=yV}=tR; x@ \w@Qt G}=Dv =OD@= 'VN@ u}= QO |O=yvW}B VwQ |=v@t Q@ w u= RQr R}t |=yV}=tR; G}=Dv =@ u; G}=Dv j}irD R= 'TBU Q=_Dv= OQwt OQmrta x@ xHwD =@ K h |=xRQr ?=DW R= Q=Wi |=yp}rLD x@ \w@Qt G}=Dv "10 pmW R= Q=Wi V}=tR; G}=Dv xU}=kt |}=Hx@=H OYQO x@ wQ}v C= Q}}eD Q=Owtv "12 pmW "|m}R}i pOt Q=yJ |wQ Q@ CWB R=Ht u=mt Q}}eD OYQO 'T=U= u}= Q@ "OwW|t OwOLt p=L Q=w}O sDU}U R= Q=_Dv= CU= VQ}PB p@=k OYQO 2 |r= 0 xR=@ QO |=xOwOLt QO p=L |=ysDU}U |=xRQr xHwD =@ [6] "OwW|t |krD Q=w}O |@=QN u=wvax@ 'Q}O=kt u}= R= V}@ |=y|}=Hx@=H w K]U xU x@ xar=]t u}= QO |OQmrta Kw]U ' [6] |v=mrB 0=72(A s =g) 0=72(A s =g) [23] Q}mwJ 0=50(As=g) [24] u= Q=mty w xDQ=Rq 0=50(As=g) 1=0(As=g)…”